JAVA PRACTICAL HANDBOOK 
1. Basic Java class 
class Ex1 
{ 
public static void main(String args[]) 
{ 
int width; 
int length; 
int height; 
width=5; 
length=12; 
height=3; 
int v; 
v=width*length*height; 
System.out.println("Volume is :"+v); 
} 
} 
Volume is :180 
JAVA PRACTICAL HANDBOOK Page 1
2. 
class Ex2 
{ 
public static void main(String args[]) 
{ 
int width; 
int length; 
int height; 
width=5; 
length=12; 
height=3; 
int v; 
v=width*length*height; 
System.out.println("Volume is :"+v); 
//Box 2 
int width1; 
int length1; 
int height1; 
width1=50; 
length1=120; 
height1=30; 
int v1; 
v1=width1*length1*height1; 
System.out.println("Volume is :"+v1); 
} 
} 
Volume is :180 
Volume is :180000 
JAVA PRACTICAL HANDBOOK Page 2
3. 
class Box 
{ 
int width; 
int length; 
int height; 
}c 
lass BoxDemo 
{ 
public static void main(String args[]) 
{ 
int x; 
x=100; 
System.out.println(x); 
Box b1; 
b1=new Box(); 
System.out.println(b1); 
b1.width=5; 
b1.length=12; 
b1.height=3; 
int v; 
v=b1.width*b1.length*b1.height; 
System.out.println("Volume is :"+v); 
} 
} 
100 
Box@119298d 
Volume is :180 
JAVA PRACTICAL HANDBOOK Page 3
4. 
class Box 
{ 
int width; 
int length; 
int height; 
} 
class BDemo 
{ 
public static void main(String args[]) 
{ 
Box b1=new Box(); 
b1.width=5; 
b1.length=12; 
b1.height=3; 
int v; 
v=b1.width*b1.length*b1.height; 
System.out.println("Volume is :"+v); 
//Box 2 
Box b2=new Box(); 
b2.width=50; 
b2.length=120; 
b2.height=30; 
int v1; 
v1=b2.width*b2.length*b2.height; 
System.out.println("Volume is :"+v1); 
} 
} 
Volume is :180 
Volume is :180000 
JAVA PRACTICAL HANDBOOK Page 4
5. Methods 
class Box 
{ 
//Variable declarations 
int width; 
int length; 
int height; 
//Creating a method to print Volume 
void printVolume() 
{ 
System.out.println("Volume is :"+(width*length*height)); 
} 
} 
class BDemo1 
{ 
public static void main(String args[]) 
{ 
Box b1=new Box(); 
b1.width=5; 
b1.length=12; 
b1.height=3; 
b1.printVolume(); 
//Box 2 
Box b2=new Box(); 
b2.width=50; 
b2.length=120; 
b2.height=30; 
b2.printVolume(); 
} 
} 
Volume is :180 
Volume is :180000 
JAVA PRACTICAL HANDBOOK Page 5
6. 
class Box 
{ 
int width; 
int length; 
int height; 
//Creating a method to print Volume 
void printVolume() 
{ 
int v; 
v=width*length*height; 
System.out.println("Volume is :"+v); 
} 
} 
class BDemo2 
{ 
public static void main(String args[]) 
{ 
Box b1=new Box(); 
b1.width=5; 
b1.length=12; 
b1.height=3; 
b1.printVolume(); 
//Box 2 
Box b2=new Box(); 
b2.width=50; 
b2.length=120; 
b2.height=30; 
b2.printVolume(); 
} 
} 
Volume is :180 
Volume is :180000 
JAVA PRACTICAL HANDBOOK Page 6
7. 
class Box 
{ 
int width; 
int length; 
int height; 
//Creating a method to print Volume 
void printVolume() 
{ 
int v; 
v=width*length*height; 
System.out.println("Volume is :"+v); 
}v 
oid setValues(int w, int l, int h) 
{ 
width=w; 
length=l; 
height=h; 
} 
} 
class BDemo3 
{ 
public static void main(String args[]) 
{ 
Box b1=new Box(); 
b1.setValues(5,12,3); 
b1.printVolume(); 
Box b2=new Box(); 
b2.setValues(50,120,30); 
b2.printVolume(); 
} 
} 
Volume is :180 
Volume is :180000 
JAVA PRACTICAL HANDBOOK Page 7
8. Methods with a return type 
class Box 
{ 
int width; 
int length; 
int height; 
//Creating a method to print Volume 
void printVolume() 
{ 
int v; 
v=width*length*height; 
System.out.println("Volume is :"+v); 
}v 
oid setValues(int w, int l, int h) 
{ 
width=w; 
length=l; 
height=h; 
}i 
nt getVolume() 
{ 
int v; 
v=width*length*height; 
return v; 
} 
}c 
lass BDemo4 
{ 
public static void main(String args[]) 
{ 
Box b1=new Box(); 
b1.setValues(5,12,3); 
int v1=b1.getVolume();//returs volume (int) 
v1+=100; 
System.out.println("Volume :"+v1); 
} 
} 
Volume :280 
JAVA PRACTICAL HANDBOOK Page 8
9. 
class A 
{ 
int tot(int i, int j) 
{ 
int k=i+j; 
System.out.println("tot :"+k); 
return k; 
} 
} 
class DemoA 
{ 
public static void main(String args[]) 
{ 
A a1=new A(); 
int t=a1.tot(10,20); 
t++; 
System.out.println("Tot now :"+t); 
} 
} 
tot :30 
Tot now :31 
JAVA PRACTICAL HANDBOOK Page 9
10. 
class A 
{ 
int tot(int i, int j) 
{ 
int k=i+j; 
System.out.println("tot :"+k); 
return k; 
} 
} 
class DemoA1 
{ 
public static void main(String args[]) 
{ 
A a1=new A(); 
a1.tot(10,20); 
} 
} 
tot :30 
JAVA PRACTICAL HANDBOOK Page 10
11. Default values of attributes 
class Box 
{ 
int width; 
int length; 
int height; 
//Creating a method to print Volume 
void printVolume() 
{ 
int v; 
v=width*length*height; 
System.out.println("Volume is :"+v); 
}v 
oid setValues(int w, int l, int h) 
{ 
width=w; 
length=l; 
height=h; 
}i 
nt getVolume() 
{ 
int v; 
v=width*length*height; 
return v; 
} 
}c 
lass BDemo5 
{ 
public static void main(String args[]) 
{ 
Box b1=new Box(); 
b1.printVolume(); 
} 
} 
Volume is :180 
Volume is :180000 
JAVA PRACTICAL HANDBOOK Page 11
12. 
class Box 
{ 
int width=10; 
int length=10; 
int height=10; 
//Creating a method to print Volume 
void printVolume() 
{ 
int v; 
v=width*length*height; 
System.out.println("Volume is :"+v); 
} 
void setValues(int w, int l, int h) 
{ 
width=w; 
length=l; 
height=h; 
} 
int getVolume() 
{ 
int v; 
v=width*length*height; 
return v; 
} 
} 
class BDemo6 
{ 
public static void main(String args[]) 
{ 
Box b1=new Box(); 
b1.printVolume(); 
} 
} 
Volume is :1000 
JAVA PRACTICAL HANDBOOK Page 12
13. Constructors 
class Box 
{ 
Box() 
{ 
System.out.println("a box is created.."); 
} 
}c 
lass BDemo7 
{ 
public static void main(String args[]) 
{ 
Box b1=new Box(); //Prints "a box is created.." calling Box 
constructor 
Box b2=new Box(); //Prints "a box is created.." 
} 
} 
a box is created.. 
a box is created.. 
JAVA PRACTICAL HANDBOOK Page 13
14. 
class Box 
{ 
int width=10; 
int length=10; 
int height=10; 
Box() 
{ 
width=2; 
length=2; 
height=2; 
}/ 
/Creating a method to print Volume 
void printVolume() 
{ 
int v; 
v=width*length*height; 
System.out.println("Volume is :"+v); 
} 
} 
class BDemo8 
{ 
public static void main(String args[]) 
{ 
Box b1=new Box(); 
b1.printVolume();//prints Volume is 8 calling Box 
Constructor 
} 
} 
Volume is :8 
JAVA PRACTICAL HANDBOOK Page 14
15. 
class Box 
{ 
int width; 
int length; 
int height; 
Box(int w, int l, int h) 
{ 
width=w; 
length=l; 
height=h; 
}/ 
/Creating a method to print Volume 
void printVolume() 
{ 
int v; 
v=width*length*height; 
System.out.println("Volume is :"+v); 
} 
}c 
lass BDemo9 
{ 
public static void main(String args[]) 
{ 
Box b1=new Box(5,12,3);//Calling constructor with parameters 
b1.printVolume(); 
Box b2=new Box(50,120,30); 
b2.printVolume(); 
} 
} 
Volume is :180 
Volume is :180000 
JAVA PRACTICAL HANDBOOK Page 15
16. Method Overloading 
class Box 
{ 
int width; 
int length; 
int height; 
//Creating a method to print Volume 
void printVolume() 
{ 
int v; 
v=width*length*height; 
System.out.println("Volume is :"+v); 
}v 
oid setValues(int w, int l, int h) 
{ 
width=w; 
length=l; 
height=h; 
}v 
oid setValues(int l) 
{ 
width=l; 
length=l; 
height=l; 
} 
}c 
lass BDemo10 
{ 
public static void main(String args[]) 
{ 
Box b1=new Box(); 
b1.setValues(2,3,6); 
b1.printVolume(); 
Box b2=new Box(); 
b2.setValues(5);//Call overloaded method "setValues(int)" 
b2.printVolume(); 
} 
} 
Volume is :36 
Volume is :125 
JAVA PRACTICAL HANDBOOK Page 16
17. Example for "this" 
class Black 
{ 
int a; 
void setA(int a) 
{ 
a=a; //call "this.a=a" 
}v 
oid setB(int a) 
{ 
this.a=a; 
} 
}c 
lass DemoBlack 
{ 
public static void main(String args[]) 
{ 
Black a1=new Black(); 
a1.setA(10); 
System.out.println("Without this "+a1.a); 
a1.setB(10); 
System.out.println("Using this "+a1.a); 
} 
} 
Without this 0 
Using this 10 
JAVA PRACTICAL HANDBOOK Page 17
18. Primitive VS Ref. Variables 
class Box 
{ 
int length; 
int width; 
int height; 
Box b1; 
}c 
lass BDemo11 
{ 
public static void main(String args[]) 
{ 
Box ob1=new Box(); 
System.out.println(ob1.length); 
System.out.println(ob1.b1); 
ob1.length=12; 
ob1.width=5; 
ob1.height=3; 
ob1.b1=new Box(); 
System.out.println(ob1.length); 
System.out.println(ob1.b1); 
} 
} 
0 null 
12 
Box@f72617 
JAVA PRACTICAL HANDBOOK Page 18
19. 
class Box 
{ 
int length; 
int width; 
int height; 
Box b1; 
Box() 
{ 
length=1; 
width=1; 
height=1; 
b1=this; 
}v 
oid setValues(int length, int width, int height) 
{ 
b1.length=length;//this.length=length; 
} 
}c 
lass BDemo12 
{ 
public static void main(String args[]) 
{ 
Box ob1=new Box(); 
System.out.println(ob1.length); 
System.out.println(ob1.b1); 
} 
} 
1 
Box@119298d 
JAVA PRACTICAL HANDBOOK Page 19
20. 
class A 
{ 
int a; 
X x1; 
Y y1; 
Z z1; 
}c 
lass BDemo13 
{ 
public static void main(String args[]) 
{ 
A a1=new A(); 
System.out.println(a1.a); 
System.out.println(a1.x1); 
System.out.println(a1.y1); 
System.out.println(a1.z1); 
System.out.println("********"); 
a1.a=100; 
a1.x1=new X(); 
a1.y1=new Y(); 
System.out.println(a1.a); 
System.out.println(a1.x1); 
System.out.println(a1.y1); 
System.out.println(a1.z1); 
} 
}c 
lass X{} 
class Y{} 
class Z{} 
0 null 
null 
null 
******** 
100 
X@1fc4bec 
Y@dc8569 
null 
JAVA PRACTICAL HANDBOOK Page 20
21. Call By Values 
class ADemo2 
{ 
public static void main(String args[]) 
{ 
int x=10; 
System.out.println("X :"+x); 
A a1=new A(); 
a1.incr(x); 
System.out.println("X :"+x); 
} 
}c 
lass A 
{ 
void incr(int x) 
{ 
x++; 
System.out.println("X :"+x); 
} 
} 
X :10 
X :11 
X :10 
JAVA PRACTICAL HANDBOOK Page 21
22. Call By Ref 
class BDemo14 
{ 
public static void main(String args[]) 
{ 
V v1=new V(); 
System.out.println("X :"+v1.x); 
A a1=new A(); 
a1.incr(v1); 
System.out.println("X :"+v1.x); 
} 
}c 
lass A 
{ 
void incr(V v1) 
{ 
v1.x++; 
System.out.println("X :"+v1.x); 
} 
}c 
lass V 
{ 
int x=10; 
} 
X :10 
X :11 
X :11 
JAVA PRACTICAL HANDBOOK Page 22
23. Call by values 
class BDemo15 
{ 
public static void main(String args[]) 
{ 
int x=10, y=20; 
System.out.println(x+" "+y); 
A a1=new A(); 
a1.change(x,y); 
System.out.println(x+" "+y); 
} 
}c 
lass A 
{ 
void change(int x, int y) 
{ 
int z; 
z=x; 
x=y; 
y=z; 
System.out.println(x+" "+y); 
} 
} 
10 20 
20 10 
10 20 
JAVA PRACTICAL HANDBOOK Page 23
24. Static variables 
class A 
{ 
int a; 
int b; 
} 
class BDemo16 
{ 
public static void main(String args[]) 
{ 
A a1=new A(); 
a1.a=10; 
a1.b=20; 
System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); 
A a2=new A(); 
a2.a=100; 
a2.b=200; 
System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); 
} 
} 
Object a1 a :10 b :20 
Object a1 a :10 b :20 
JAVA PRACTICAL HANDBOOK Page 24
25. 
class A 
{ 
int a; 
static int b; 
} 
class BDemo17 
{ 
public static void main(String args[]) 
{ 
A a1=new A(); 
a1.a=10; 
a1.b=20; 
System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); 
A a2=new A(); 
a2.a=100; 
a2.b=200; 
System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); 
} 
} 
Object a1 a :10 b :20 
Object a1 a :10 b :200 
JAVA PRACTICAL HANDBOOK Page 25
26. 
class A 
{ 
int a; 
static int b; 
} 
class BDemo18 
{ 
public static void main(String args[]) 
{ 
A a1=new A(); 
a1.a=10; 
a1.b=20; 
System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); 
A a2=new A(); 
a2.a=100; 
a2.b=200; 
System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); 
System.out.println("Object a2 a :"+a2.a+" b :"+a2.b); 
a1.a=10000; 
a1.b=20000; 
System.out.println("Object a2 a :"+a2.a+" b :"+a2.b); 
A a3=new A(); 
System.out.println("Object a3 a :"+a3.a+" b :"+a3.b); 
A.b=2000000;// 
System.out.println("a1.b :"+a1.b+" a2.b :"+a2.b+" a3.b 
:"+a3.b); 
} 
} 
Object a1 a :10 b :20 
Object a1 a :10 b :200 
Object a2 a :100 b :200 
Object a2 a :100 b :20000 
Object a3 a :0 b :20000 
a1.b :2000000 a2.b :2000000 a3.b :2000000 
JAVA PRACTICAL HANDBOOK Page 26
27. Static methods 
class A 
{ 
void m1() 
{ 
System.out.println("m1"); 
}s 
tatic void m2() 
{ 
System.out.println("m2"); 
} 
} 
class BDemo19 
{ 
public static void main(String args[]) 
{ 
A ob=new A(); 
ob.m1(); 
A.m2();// without creating object can call method 
} 
} 
m1 
m2 
JAVA PRACTICAL HANDBOOK Page 27
28. 
class A 
{ 
int x=10; 
static int y=20; 
void m1() 
{ 
System.out.println(x); 
System.out.println(y); 
} 
} 
class BDemo20 
{ 
public static void main(String args[]) 
{ 
new A().m1(); 
} 
} 
10 
20 
JAVA PRACTICAL HANDBOOK Page 28
29. 
class A 
{ 
int x=10; 
static int y=20; 
void m1() 
{ 
System.out.println(this.x); 
System.out.println(this.y); 
} 
} 
class BDemo21 
{ 
public static void main(String args[]) 
{ 
new A().m1(); 
} 
} 
10 
20 
JAVA PRACTICAL HANDBOOK Page 29
30. Object / static initializer 
class A 
{ 
static 
{ 
System.out.print("1 "); 
}{ 
System.out.print("2 "); 
}A 
() 
{ 
System.out.print("3 "); 
}v 
oid m1() 
{ 
System.out.print("4 "); 
}s 
tatic void m2() 
{ 
System.out.print("5 "); 
} 
} 
class BDemo22 
{ 
public static void main(String args[]) 
{ 
new A(); 
A.m2(); 
} 
} 
1 2 3 5 
JAVA PRACTICAL HANDBOOK Page 30
31. 
class A 
{ 
int a; 
void printA() 
{ 
System.out.println("a :"+a); 
} 
}c 
lass B extends A 
{ 
int b; 
void printB() 
{ 
System.out.println("b :"+b); 
}v 
oid printAB() 
{ 
System.out.println("a+b :"+(a+b)); 
}v 
oid callAB() 
{ 
printA(); 
printB(); 
} 
}c 
lass BDemo23 
{ 
public static void main(String args[]) 
{ 
B b1=new B(); 
b1.a=10; 
b1.b=20; 
b1.printA(); 
b1.printB(); 
b1.printAB(); 
b1.callAB(); 
} 
} 
a :10 
b :20 
a+b :30 
a :10 
b :20 
JAVA PRACTICAL HANDBOOK Page 31
32. super class Constructor 
class A 
{ 
int a; 
A() 
{ 
System.out.println("A()"); 
}A 
(int i) 
{ 
System.out.println("A(int)"); 
}v 
oid printA() 
{ 
System.out.println("a :"+a); 
} 
}c 
lass B extends A 
{ 
int b; 
B() 
{ 
System.out.println("B()"); 
}B 
(int i) 
{ 
System.out.println("B(int)"); 
}v 
oid printB() 
{ 
System.out.println("b :"+b); 
}v 
oid printAB() 
{ 
System.out.println("a+b :"+(a+b)); 
}v 
oid callAB() 
{ 
printA(); 
printB(); 
} 
}c 
lass BDemo24 
{ 
public static void main(String args[]) 
{ 
B b1=new B(); 
B b2=new B(100); 
} 
JAVA PRACTICAL HANDBOOK Page 32
} 
A() 
B() 
A() 
B(int) 
33. 
class A 
{ 
int a; 
A() 
{ 
System.out.println("A()"); 
}A 
(int i) 
{ 
System.out.println("A(int)"); 
}v 
oid printA() 
{ 
System.out.println("a :"+a); 
} 
} 
class B extends A 
{ 
int b; 
B() 
{ 
super(); 
System.out.println("B()"); 
}B 
(int i) 
{ 
super(); 
System.out.println("B(int)"); 
}v 
oid printB() 
{ 
System.out.println("b :"+b); 
}v 
oid printAB() 
{ 
System.out.println("a+b :"+(a+b)); 
}void callAB(){ 
JAVA PRACTICAL HANDBOOK Page 33
printA(); 
printB(); 
} 
}c 
lass BDemo25 
{ 
public static void main(String args[]) 
{ 
B b1=new B(); 
B b2=new B(100); 
} 
} 
A() 
B() 
A() 
B(int) 
JAVA PRACTICAL HANDBOOK Page 34
34. 
class A 
{ 
int a; 
A() 
{ 
System.out.println("A()"); 
}A 
(int i) 
{ 
System.out.println("A(int)"); 
}v 
oid printA() 
{ 
System.out.println("a :"+a); 
} 
}c 
lass B extends A 
{ 
int b; 
B() 
{ 
super();// 
System.out.println("B()"); 
}B 
(int i) 
{ 
super(i);//super(100); 
System.out.println("B(int)"); 
}v 
oid printB() 
{ 
System.out.println("b :"+b); 
}v 
oid printAB() 
{ 
System.out.println("a+b :"+(a+b)); 
}v 
oid callAB() 
{ 
printA(); 
printB(); 
} 
}c 
lass BDemo26 
{ 
public static void main(String args[]) 
{ 
B b1=new B(); 
JAVA PRACTICAL HANDBOOK Page 35
B b2=new B(100); 
} 
} 
A() 
B() 
A(int) 
B(int) 
JAVA PRACTICAL HANDBOOK Page 36
35. 
class A 
{ 
int a; 
A() 
{ 
System.out.println("A()"); 
}A 
(int i) 
{ 
System.out.println("A(int)"); 
}v 
oid printA() 
{ 
System.out.println("a :"+a); 
} 
}c 
lass B extends A 
{ 
int b; 
B() 
{ 
super();// 
System.out.println("B()"); 
}B 
(int i) 
{ 
super(i);//super(100); 
System.out.println("B(int)"); 
}v 
oid printB() 
{ 
System.out.println("b :"+b); 
}v 
oid printAB() 
{ 
System.out.println("a+b :"+(a+b)); 
}v 
oid callAB() 
{ 
printA(); 
printB(); 
} 
}c 
lass BDemo27 
{ 
public static void main(String args[]) 
{ 
A a1; 
JAVA PRACTICAL HANDBOOK Page 37
a1=new B(); 
//B b1=new A();//Error 
a1.a=10; 
// a1.b=20; Error 
a1.printA(); 
/* a1.printB();//Error 
a1.printAB();//Error 
a1.callAB();//Error */ 
} 
} 
A() 
B() 
a :10 
JAVA PRACTICAL HANDBOOK Page 38
36. Method Overriding 
class A 
{ 
int a; 
void printA() 
{ 
System.out.println("a :"+a); 
}v 
oid print() 
{ 
System.out.println("A.print"); 
} 
} 
class B extends A 
{ 
int b; 
void printB() 
{ 
System.out.println("b :"+b); 
}v 
oid printAB() 
{ 
System.out.println("a+b :"+(a+b)); 
}v 
oid callAB() 
{ 
printA(); 
printB(); 
}v 
oid print() 
{ 
System.out.println("B.print"); 
} 
} 
class BDemo28 
{ 
public static void main(String args[]) 
{ 
A a1=new B(); 
a1.print(); 
} 
} 
B.print 
JAVA PRACTICAL HANDBOOK Page 39
37. 
class Vehicle 
{ 
void park() 
{} 
}c 
lass Car extends Vehicle 
{ 
void park() 
{ 
System.out.println("Car park"); 
} 
}c 
lass Bus extends Vehicle 
{ 
void park() 
{ 
System.out.println("Bus park"); 
} 
}c 
lass MB extends Vehicle 
{ 
void park() 
{ 
System.out.println("MB park"); 
} 
}c 
lass BDemo29 
{ 
public static void main(String argsp[]) 
{ 
Vehicle ob; 
ob=new Car(); 
ob.park(); //print "Car park" 
ob=new Bus(); 
ob.park(); //print "Bus park" 
ob=new MB(); 
ob.park(); //print "MB park" 
} 
} 
Car park 
Bus park 
MB park 
JAVA PRACTICAL HANDBOOK Page 40
38. 
class A 
{ 
static 
{ 
System.out.print("1 "); 
}{ 
System.out.print("2 "); 
}A 
() 
{ 
System.out.print("3 "); 
}s 
tatic void mA() 
{ 
System.out.print("4 "); 
} 
}c 
lass B extends A 
{ 
static 
{ 
System.out.print("5 "); 
}{ 
System.out.print("6 "); 
}B 
() 
{ 
System.out.print("7 "); 
}s 
tatic void mB() 
{ 
System.out.print("8 "); 
} 
}c 
lass BDemo30 
{ 
public static void main(String args[]) 
{ 
new B(); 
} 
} 
1 5 2 3 6 7 
JAVA PRACTICAL HANDBOOK Page 41
39. 
class A 
{ 
static 
{ 
System.out.print("1 "); 
}{ 
System.out.print("2 "); 
}A 
() 
{ 
System.out.print("3 "); 
}s 
tatic void mA() 
{ 
System.out.print("4 "); 
} 
}c 
lass B extends A 
{ 
static 
{ 
System.out.print("5 "); 
}{ 
System.out.print("6 "); 
}B 
() 
{ 
System.out.print("7 "); 
}s 
tatic void mB() 
{ 
System.out.print("8 "); 
} 
}c 
lass BDemo31 
{ 
public static void main(String args[]) 
{ 
B.mA(); //Prints 1 4 
} 
} 
1 4 
JAVA PRACTICAL HANDBOOK Page 42
40. Way of invoking "super()" and "this()" 
class A 
{ 
A(int i) 
{ 
System.out.println("A(int) :"+i); 
} 
}c 
lass B extends A 
{ 
B(int i) 
{ 
super(i); 
System.out.println("B(int) :"+i); 
} 
}c 
lass BDemo32 
{ 
public static void main(String args[]) 
{ 
new B(100); 
} 
} 
A(int) :100 
B(int) :100 
JAVA PRACTICAL HANDBOOK Page 43
41. 
class A 
{ 
A(int i) 
{ 
System.out.println("A(int) :"+i); 
}A 
(int i, int j) 
{ 
System.out.println("A(int,int) :"+i+" "+j); 
} 
}c 
lass B extends A 
{ 
B(int i) 
{ 
super(100); 
System.out.println("B(int) :"+i); 
}B 
(int i, int j ) 
{ 
super(i, j); 
System.out.println("B(int, int) :"+i+" "+j); 
} 
}c 
lass BDemo33 
{ 
public static void main(String args[]) 
{ 
new B(100,200); 
} 
} 
A(int,int) :100 200 
B(int, int) :100 200 
JAVA PRACTICAL HANDBOOK Page 44
42. "calling this" 
class A 
{ 
int a=100; 
A() 
{ 
this(1); 
}A 
(int i) 
{ 
a=i; 
} 
}c 
lass B extends A 
{ 
int b=200; 
B(){ 
this(1); 
}B 
(int i) 
{ 
super(i); 
b=i; 
}B 
(int i, int j) 
{ 
super(i); 
b=j;// 
}v 
oid printAB() 
{ 
System.out.println("a b :"+a+" "+b); 
} 
}c 
lass BDemo34 
{ 
public static void main(String args[]) 
{ 
B b1=new B(); 
b1.printAB(); 
B b2=new B(10); 
b2.printAB(); 
B b3=new B(100,200); 
b3.printAB(); 
} 
} 
JAVA PRACTICAL HANDBOOK Page 45
a b :1 1 
a b :10 10 
a b :100 200 
JAVA PRACTICAL HANDBOOK Page 46
43. "this" VS "super" 
class A 
{ 
int a=100; 
A() 
{ 
this(1); 
}A 
(int i) 
{ 
a=i; 
} 
}c 
lass B extends A 
{ 
int b=200; 
B() 
{ 
this(1); 
}B 
(int i) 
{ 
super(i); 
b=i; 
}B 
(int i, int j) 
{ 
super(i); 
b=j;// 
}v 
oid printAB() 
{ 
System.out.println("a b :"+a+" "+b); 
} 
}c 
lass BDemo35 
{ 
public static void main(String args[]) 
{ 
B b1=new B(); 
b1.printAB(); 
B b2=new B(10); 
b2.printAB(); 
B b3=new B(100,200); 
b3.printAB(); 
} 
} 
JAVA PRACTICAL HANDBOOK Page 47
a b :1 1 
a b :10 10 
a b :100 200 
JAVA PRACTICAL HANDBOOK Page 48
44. 
class A 
{ 
void print() 
{ 
System.out.println("A.print"); 
} 
}c 
lass B extends A 
{ 
void print() 
{ 
System.out.println("B.print"); 
} 
}c 
lass BDemo36 
{ 
public static void main(String args[]){ 
B b1=new B(); 
b1.print(); //prints "B.print" 
} 
} 
B.print 
JAVA PRACTICAL HANDBOOK Page 49
45. 
class A 
{ 
void print() 
{ 
System.out.println("A.print"); 
} 
}c 
lass B extends A 
{ 
void print() 
{ 
System.out.println("B.print"); 
} 
}c 
lass BDemo37 
{ 
public static void main(String args[]) 
{ 
A a1=new B(); 
a1.print();//print "B.print" 
} 
} 
B.print 
JAVA PRACTICAL HANDBOOK Page 50
46. 
class A 
{ 
int a=100; 
}c 
lass B extends A 
{ 
int a=200; 
}c 
lass BDemo38 
{ 
public static void main(String args[]) 
{ 
B b1=new B(); 
int x=b1.a; 
System.out.println(x);//print "200" 
} 
} 
200 
JAVA PRACTICAL HANDBOOK Page 51
47. 
class A 
{ 
int a=100; 
}c 
lass B extends A 
{ 
int a=200; 
}c 
lass BDemo39 
{ 
public static void main(String args[]) 
{ 
A a1=new B(); 
int x=a1.a; 
System.out.println(x);//print "100" 
} 
} 
100 
JAVA PRACTICAL HANDBOOK Page 52
48. 
class A 
{ 
int a=100; 
}c 
lass B extends A 
{ 
int a=200; 
void m() 
{ 
System.out.println("a :"+a); 
} 
}c 
lass BDemo40 
{ 
public static void main(String args[]) 
{ 
B b1=new B(); 
b1.m(); //prints "a :200" 
} 
} 
200 
JAVA PRACTICAL HANDBOOK Page 53
49. super.a 
class A 
{ 
int a=100; 
}c 
lass B extends A 
{ 
int a=200; 
void m() 
{ 
System.out.println("a :"+super.a); 
} 
}c 
lass BDemo41 
{ 
public static void main(String args[]) 
{ 
B b1=new B(); 
b1.m(); 
} 
} 
a :100 
50. 
class A 
{ 
int a=100; 
}c 
lass B extends A 
{ 
int a=200; 
}c 
lass C extends B 
{ 
int a=300; 
void m() 
{ 
System.out.println("a :"+a); 
} 
}c 
lass BDemo42 
{ 
public static void main(String args[]) 
{ 
C c1=new C(); 
c1.m(); 
} 
JAVA PRACTICAL HANDBOOK Page 54
} 
a :300 
JAVA PRACTICAL HANDBOOK Page 55
51. 
class A 
{ 
void print() 
{ 
System.out.println("A.print"); 
} 
}c 
lass B extends A 
{ 
void print() 
{ 
System.out.println("B.print"); 
} 
}c 
lass C extends B 
{ 
void print() 
{ 
System.out.println("C.print"); 
}v 
oid m() 
{ 
print(); 
} 
}c 
lass BDemo43 
{ 
public static void main(String args[]) 
{ 
C c1=new C(); 
c1.m(); 
} 
} 
C.print 
JAVA PRACTICAL HANDBOOK Page 56
52. 
class A 
{ 
void print() 
{ 
System.out.println("A.print"); 
} 
}c 
lass B extends A 
{ 
void print() 
{ 
System.out.println("B.print"); 
} 
}c 
lass C extends B 
{ 
void print() 
{ 
System.out.println("C.print"); 
}v 
oid m() 
{ 
super.print(); 
} 
}c 
lass BDemo44 
{ 
public static void main(String args[]) 
{ 
C c1=new C(); 
c1.m(); 
} 
} 
B.print 
JAVA PRACTICAL HANDBOOK Page 57
53. 
class A 
{ 
A() 
{ 
print(); 
}v 
oid print() 
{ 
System.out.println("A.print"); 
} 
}c 
lass B extends A 
{ 
void print() 
{ 
System.out.println("B.print"); 
} 
} 
class BDemo45 
{ 
public static void main(String args[]) 
{ 
new B(); 
} 
} 
B.print 
JAVA PRACTICAL HANDBOOK Page 58
54. 
class A 
{ 
int a=100; 
A() 
{ 
print(); 
}v 
oid print() 
{ 
System.out.println("A.print "+a); 
} 
}c 
lass B extends A 
{ 
int a=200; 
void print() 
{ 
System.out.println("B.print "+a); 
} 
} 
class BDemo46 
{ 
public static void main(String args[]) 
{ 
new B(); 
} 
} 
B.print 0 
JAVA PRACTICAL HANDBOOK Page 59
55. 
class A 
{ 
int a=100; 
A() 
{ 
print(); 
}v 
oid print() 
{ 
System.out.println("A.print "+a); 
} 
}c 
lass B extends A 
{ 
//int a=200; 
void print() 
{ 
System.out.println("B.print "+a); 
} 
} 
class BDemo47 
{ 
public static void main(String args[]) 
{ 
new B(); 
} 
} 
B.print 100 
JAVA PRACTICAL HANDBOOK Page 60
56. 
class A 
{ 
int a=100; 
A() 
{ 
print(); 
}v 
oid print() 
{ 
System.out.println("A.print "+a); 
} 
}c 
lass B extends A 
{ 
static int a=200; 
void print() 
{ 
System.out.println("B.print "+a); 
} 
} 
class BDemo48 
{ 
public static void main(String args[]) 
{ 
new B(); 
} 
} 
B.print 200 
JAVA PRACTICAL HANDBOOK Page 61
57. 
class A 
{ 
A() 
{ 
print(); 
}s 
tatic void print() 
{ 
System.out.println("A.print "); 
} 
}c 
lass B extends A 
{ 
static void print() 
{ 
System.out.println("B.print "); 
} 
} 
class BDemo49 
{ 
public static void main(String args[]) 
{ 
new B(); 
} 
} 
A.print 
JAVA PRACTICAL HANDBOOK Page 62
58. Private methods 
class A 
{ 
void m1() 
{ 
System.out.println("A.m1"); 
}p 
rivate void m2() 
{ 
System.out.println("A.m2"); 
}v 
oid mA() 
{ 
m1(); 
m2(); 
} 
} 
class BDemo50 
{ 
public static void main(String asrgs[]) 
{ 
new A().mA(); 
new A().m1(); 
/* new A().m2(); error: m2() has private access in A new 
A().m2(); */ 
} 
} 
A.m1 
A.m2 
A.m1 
JAVA PRACTICAL HANDBOOK Page 63
59. 
class A 
{ 
A() 
{ 
print(); 
}p 
rivate void print() 
{ 
System.out.println("A.print "); 
} 
}c 
lass B extends A 
{ 
void print() 
{ 
System.out.println("B.print "); 
} 
} 
class BDemo51 
{ 
public static void main(String args[]){ 
new B(); 
} 
} 
A.print 
JAVA PRACTICAL HANDBOOK Page 64
60. 
class A 
{ 
X print() 
{ 
X x1=new X(); 
System.out.println("X.print "); 
return x1; 
} 
}c 
lass B extends A 
{ 
Y print() 
{ 
Y y1=new Y(); 
System.out.println("Y.print "); 
return y1; 
} 
} 
class BDemo52 
{ 
public static void main(String args[]) 
{ 
A a1=new B(); 
X ob= a1.print(); 
} 
}c 
lass X{} 
class Y extends X {} 
Y.print 
JAVA PRACTICAL HANDBOOK Page 65
61. class "Object" 
class A 
{}c 
lass BDemo53 
{ 
public static void main(String args[]) 
{ 
A a1=new A(); 
System.out.println(a1.toString()); 
System.out.println(a1.hashCode()); 
} 
} 
A@10385c1 
17008065 
JAVA PRACTICAL HANDBOOK Page 66
62. 
class A extends Object 
{}c 
lass BDemo54 
{ 
public static void main(String args[]) 
{ 
A a1=new A(); 
System.out.println(a1.toString()); 
System.out.println(a1.hashCode()); 
} 
} 
A@10385c1 
17008065 
63. Demonstrate methods "toString()" 
class A 
{ 
int a; 
A(int i) 
{ 
a=i; 
} 
}c 
lass BDemo55 
{ 
public static void main(String args[]) 
{ 
A a1=new A(100); 
System.out.println(a1.toString()); 
System.out.println(a1); 
} 
} 
A@10385c1 
A@10385c1 
JAVA PRACTICAL HANDBOOK Page 67
64. 
class A 
{ 
int a; 
A(int i) 
{ 
a=i; 
}p 
ublic String toString() 
{ 
return ""+a; 
} 
}c 
lass BDemo56 
{ 
public static void main(String args[]) 
{ 
A a1=new A(100); 
System.out.println(a1.toString()); 
System.out.println(a1); 
} 
} 
100 
100 
JAVA PRACTICAL HANDBOOK Page 68
65. 
class A 
{ 
public String toString() 
{ 
return "class A"; 
} 
}c 
lass B extends A 
{ 
public String toString() 
{ 
return "class B"; 
} 
}c 
lass C extends B 
{ 
public String toString() 
{ 
return "class C"; 
} 
}c 
lass BDemo57 
{ 
public static void main(String args[]) 
{ 
Object ob; 
ob=new A(); 
System.out.println(ob); 
ob=new B(); 
System.out.println(ob); 
ob=new C(); 
System.out.println(ob); 
} 
} 
class A 
class B 
class C 
JAVA PRACTICAL HANDBOOK Page 69
66. Demonstrate methods "equals(Object ob)" of class Object 
class A 
{ 
int a; 
A(int i) 
{ 
a=i; 
} 
}c 
lass BDemo58 
{ 
public static void main(String args[]) 
{ 
A a1=new A(100); 
A a2=new A(100); 
A a3=new A(200); 
A a4=a1; 
System.out.println(a1==a2); 
System.out.println(a1==a3); 
System.out.println(a1==a4); 
} 
} 
false 
false 
true 
JAVA PRACTICAL HANDBOOK Page 70
67. 
class A 
{ 
int a; 
A(int i) 
{ 
a=i; 
} 
}c 
lass BDemo59 
{ 
public static void main(String args[]) 
{ 
A a1=new A(100); 
A a2=new A(100); 
A a3=new A(200); 
A a4=a1; 
System.out.println(a1.equals(a2)); 
System.out.println(a1.equals(a3)); 
System.out.println(a1.equals(a4)); 
} 
} 
false 
false 
true 
JAVA PRACTICAL HANDBOOK Page 71
68. 
class A 
{ 
int a; 
A(int i) 
{ 
a=i; 
}p 
ublic boolean equals(Object ob) 
{ 
A a1=(A)ob; 
return a1.a==this.a ; 
} 
}c 
lass BDemo60 
{ 
public static void main(String args[]) 
{ 
A a1=new A(100); 
A a2=new A(100); 
A a3=new A(200); 
A a4=a1; 
System.out.println(a1.equals(a2)); 
System.out.println(a1.equals(a3)); 
System.out.println(a1.equals(a4)); 
} 
} 
true 
false 
true 
JAVA PRACTICAL HANDBOOK Page 72
69. Methods Overloading for class Type 
class BDemo61 
{ 
static void m(A a) 
{ 
System.out.println("m(A)"); 
}s 
tatic void m(B a) 
{ 
System.out.println("m(B)"); 
}s 
tatic void m(C a) 
{ 
System.out.println("m(C)"); 
}p 
ublic static void main(String args[]) 
{ 
A a1=new A(); 
B b1=new B(); 
C c1=new C(); 
BDemo61.m(a1); 
BDemo61.m(b1); 
BDemo61.m(c1); 
} 
}c 
lass A{} 
class B{} 
class C{} 
m(A) 
m(B) 
m(C) 
JAVA PRACTICAL HANDBOOK Page 73
70. 
class BDemo62 
{ 
static void m(A a) 
{ 
System.out.println("m(A)"); 
}s 
tatic void m(B a) 
{ 
System.out.println("m(B)"); 
}p 
ublic static void main(String args[]) 
{ 
A a1=new A(); 
B b1=new B(); 
C c1=new C(); 
BDemo62.m(a1); 
BDemo62.m(b1); 
BDemo62.m(c1); 
} 
}c 
lass A{} 
class B{} 
class C extends B{} 
m(A) 
m(B) 
m(B) 
JAVA PRACTICAL HANDBOOK Page 74
71. 
class BDemo63 
{ 
static void m(A a) 
{ 
System.out.println("m(A)"); 
}s 
tatic void m(B a) 
{ 
System.out.println("m(B)"); 
}p 
ublic static void main(String args[]) 
{ 
A a1=new A(); 
B b1=new B(); 
C c1=new C(); 
BDemo63.m(a1); 
BDemo63.m(b1); 
BDemo63.m(c1); 
} 
}c 
lass A{} 
class B extends A{} 
class C extends B{} 
m(A) 
m(B) 
m(B) 
JAVA PRACTICAL HANDBOOK Page 75
72. 
class BDemo64 
{ 
static void m(Object a) 
{ 
System.out.println("m(Object)"); 
} 
public static void main(String args[]) 
{ 
A a1=new A(); 
B b1=new B(); 
C c1=new C(); 
BDemo64.m(a1); 
BDemo64.m(b1); 
BDemo64.m(c1); 
} 
}c 
lass A{} 
class B extends A{ } 
class C extends B{} 
m(Object) 
m(Object) 
m(Object) 
JAVA PRACTICAL HANDBOOK Page 76
73. Abstract Methods 
abstract class Vehicle 
{ 
abstract void park(); 
}c 
lass BDemo65 
{ 
public static void main(String args[]) 
{ 
Vehicle ob; 
ob=new Car(); 
ob.park(); 
ob=new Bus(); 
ob.park(); 
ob=new MB(); 
ob.park(); 
} 
}c 
lass Car extends Vehicle 
{ 
void park() 
{ 
System.out.println("Car park"); 
} 
}c 
lass Bus extends Vehicle 
{ 
void park() 
{ 
System.out.println("Bus park"); 
} 
}c 
lass MB extends Vehicle 
{ 
void park() 
{ 
System.out.println("MB park"); 
} 
} 
Car park 
Bus park 
MB park 
JAVA PRACTICAL HANDBOOK Page 77
74. Creating an inner class object 
class A 
{ 
int i=100; 
void m() 
{ 
System.out.print(i); 
}c 
lass Inner 
{ 
int j=10; 
void mn() 
{ 
System.out.print(i+" "); 
System.out.print(j); 
} 
} 
}c 
lass DemoA2 
{ 
public static void main(String args[]) 
{ 
A ob=new A(); 
A.Inner inOb=ob.new Inner(); 
inOb.mn(); 
} 
} 
100 10 
JAVA PRACTICAL HANDBOOK Page 78

Java_practical_handbook

  • 1.
    JAVA PRACTICAL HANDBOOK 1. Basic Java class class Ex1 { public static void main(String args[]) { int width; int length; int height; width=5; length=12; height=3; int v; v=width*length*height; System.out.println("Volume is :"+v); } } Volume is :180 JAVA PRACTICAL HANDBOOK Page 1
  • 2.
    2. class Ex2 { public static void main(String args[]) { int width; int length; int height; width=5; length=12; height=3; int v; v=width*length*height; System.out.println("Volume is :"+v); //Box 2 int width1; int length1; int height1; width1=50; length1=120; height1=30; int v1; v1=width1*length1*height1; System.out.println("Volume is :"+v1); } } Volume is :180 Volume is :180000 JAVA PRACTICAL HANDBOOK Page 2
  • 3.
    3. class Box { int width; int length; int height; }c lass BoxDemo { public static void main(String args[]) { int x; x=100; System.out.println(x); Box b1; b1=new Box(); System.out.println(b1); b1.width=5; b1.length=12; b1.height=3; int v; v=b1.width*b1.length*b1.height; System.out.println("Volume is :"+v); } } 100 Box@119298d Volume is :180 JAVA PRACTICAL HANDBOOK Page 3
  • 4.
    4. class Box { int width; int length; int height; } class BDemo { public static void main(String args[]) { Box b1=new Box(); b1.width=5; b1.length=12; b1.height=3; int v; v=b1.width*b1.length*b1.height; System.out.println("Volume is :"+v); //Box 2 Box b2=new Box(); b2.width=50; b2.length=120; b2.height=30; int v1; v1=b2.width*b2.length*b2.height; System.out.println("Volume is :"+v1); } } Volume is :180 Volume is :180000 JAVA PRACTICAL HANDBOOK Page 4
  • 5.
    5. Methods classBox { //Variable declarations int width; int length; int height; //Creating a method to print Volume void printVolume() { System.out.println("Volume is :"+(width*length*height)); } } class BDemo1 { public static void main(String args[]) { Box b1=new Box(); b1.width=5; b1.length=12; b1.height=3; b1.printVolume(); //Box 2 Box b2=new Box(); b2.width=50; b2.length=120; b2.height=30; b2.printVolume(); } } Volume is :180 Volume is :180000 JAVA PRACTICAL HANDBOOK Page 5
  • 6.
    6. class Box { int width; int length; int height; //Creating a method to print Volume void printVolume() { int v; v=width*length*height; System.out.println("Volume is :"+v); } } class BDemo2 { public static void main(String args[]) { Box b1=new Box(); b1.width=5; b1.length=12; b1.height=3; b1.printVolume(); //Box 2 Box b2=new Box(); b2.width=50; b2.length=120; b2.height=30; b2.printVolume(); } } Volume is :180 Volume is :180000 JAVA PRACTICAL HANDBOOK Page 6
  • 7.
    7. class Box { int width; int length; int height; //Creating a method to print Volume void printVolume() { int v; v=width*length*height; System.out.println("Volume is :"+v); }v oid setValues(int w, int l, int h) { width=w; length=l; height=h; } } class BDemo3 { public static void main(String args[]) { Box b1=new Box(); b1.setValues(5,12,3); b1.printVolume(); Box b2=new Box(); b2.setValues(50,120,30); b2.printVolume(); } } Volume is :180 Volume is :180000 JAVA PRACTICAL HANDBOOK Page 7
  • 8.
    8. Methods witha return type class Box { int width; int length; int height; //Creating a method to print Volume void printVolume() { int v; v=width*length*height; System.out.println("Volume is :"+v); }v oid setValues(int w, int l, int h) { width=w; length=l; height=h; }i nt getVolume() { int v; v=width*length*height; return v; } }c lass BDemo4 { public static void main(String args[]) { Box b1=new Box(); b1.setValues(5,12,3); int v1=b1.getVolume();//returs volume (int) v1+=100; System.out.println("Volume :"+v1); } } Volume :280 JAVA PRACTICAL HANDBOOK Page 8
  • 9.
    9. class A { int tot(int i, int j) { int k=i+j; System.out.println("tot :"+k); return k; } } class DemoA { public static void main(String args[]) { A a1=new A(); int t=a1.tot(10,20); t++; System.out.println("Tot now :"+t); } } tot :30 Tot now :31 JAVA PRACTICAL HANDBOOK Page 9
  • 10.
    10. class A { int tot(int i, int j) { int k=i+j; System.out.println("tot :"+k); return k; } } class DemoA1 { public static void main(String args[]) { A a1=new A(); a1.tot(10,20); } } tot :30 JAVA PRACTICAL HANDBOOK Page 10
  • 11.
    11. Default valuesof attributes class Box { int width; int length; int height; //Creating a method to print Volume void printVolume() { int v; v=width*length*height; System.out.println("Volume is :"+v); }v oid setValues(int w, int l, int h) { width=w; length=l; height=h; }i nt getVolume() { int v; v=width*length*height; return v; } }c lass BDemo5 { public static void main(String args[]) { Box b1=new Box(); b1.printVolume(); } } Volume is :180 Volume is :180000 JAVA PRACTICAL HANDBOOK Page 11
  • 12.
    12. class Box { int width=10; int length=10; int height=10; //Creating a method to print Volume void printVolume() { int v; v=width*length*height; System.out.println("Volume is :"+v); } void setValues(int w, int l, int h) { width=w; length=l; height=h; } int getVolume() { int v; v=width*length*height; return v; } } class BDemo6 { public static void main(String args[]) { Box b1=new Box(); b1.printVolume(); } } Volume is :1000 JAVA PRACTICAL HANDBOOK Page 12
  • 13.
    13. Constructors classBox { Box() { System.out.println("a box is created.."); } }c lass BDemo7 { public static void main(String args[]) { Box b1=new Box(); //Prints "a box is created.." calling Box constructor Box b2=new Box(); //Prints "a box is created.." } } a box is created.. a box is created.. JAVA PRACTICAL HANDBOOK Page 13
  • 14.
    14. class Box { int width=10; int length=10; int height=10; Box() { width=2; length=2; height=2; }/ /Creating a method to print Volume void printVolume() { int v; v=width*length*height; System.out.println("Volume is :"+v); } } class BDemo8 { public static void main(String args[]) { Box b1=new Box(); b1.printVolume();//prints Volume is 8 calling Box Constructor } } Volume is :8 JAVA PRACTICAL HANDBOOK Page 14
  • 15.
    15. class Box { int width; int length; int height; Box(int w, int l, int h) { width=w; length=l; height=h; }/ /Creating a method to print Volume void printVolume() { int v; v=width*length*height; System.out.println("Volume is :"+v); } }c lass BDemo9 { public static void main(String args[]) { Box b1=new Box(5,12,3);//Calling constructor with parameters b1.printVolume(); Box b2=new Box(50,120,30); b2.printVolume(); } } Volume is :180 Volume is :180000 JAVA PRACTICAL HANDBOOK Page 15
  • 16.
    16. Method Overloading class Box { int width; int length; int height; //Creating a method to print Volume void printVolume() { int v; v=width*length*height; System.out.println("Volume is :"+v); }v oid setValues(int w, int l, int h) { width=w; length=l; height=h; }v oid setValues(int l) { width=l; length=l; height=l; } }c lass BDemo10 { public static void main(String args[]) { Box b1=new Box(); b1.setValues(2,3,6); b1.printVolume(); Box b2=new Box(); b2.setValues(5);//Call overloaded method "setValues(int)" b2.printVolume(); } } Volume is :36 Volume is :125 JAVA PRACTICAL HANDBOOK Page 16
  • 17.
    17. Example for"this" class Black { int a; void setA(int a) { a=a; //call "this.a=a" }v oid setB(int a) { this.a=a; } }c lass DemoBlack { public static void main(String args[]) { Black a1=new Black(); a1.setA(10); System.out.println("Without this "+a1.a); a1.setB(10); System.out.println("Using this "+a1.a); } } Without this 0 Using this 10 JAVA PRACTICAL HANDBOOK Page 17
  • 18.
    18. Primitive VSRef. Variables class Box { int length; int width; int height; Box b1; }c lass BDemo11 { public static void main(String args[]) { Box ob1=new Box(); System.out.println(ob1.length); System.out.println(ob1.b1); ob1.length=12; ob1.width=5; ob1.height=3; ob1.b1=new Box(); System.out.println(ob1.length); System.out.println(ob1.b1); } } 0 null 12 Box@f72617 JAVA PRACTICAL HANDBOOK Page 18
  • 19.
    19. class Box { int length; int width; int height; Box b1; Box() { length=1; width=1; height=1; b1=this; }v oid setValues(int length, int width, int height) { b1.length=length;//this.length=length; } }c lass BDemo12 { public static void main(String args[]) { Box ob1=new Box(); System.out.println(ob1.length); System.out.println(ob1.b1); } } 1 Box@119298d JAVA PRACTICAL HANDBOOK Page 19
  • 20.
    20. class A { int a; X x1; Y y1; Z z1; }c lass BDemo13 { public static void main(String args[]) { A a1=new A(); System.out.println(a1.a); System.out.println(a1.x1); System.out.println(a1.y1); System.out.println(a1.z1); System.out.println("********"); a1.a=100; a1.x1=new X(); a1.y1=new Y(); System.out.println(a1.a); System.out.println(a1.x1); System.out.println(a1.y1); System.out.println(a1.z1); } }c lass X{} class Y{} class Z{} 0 null null null ******** 100 X@1fc4bec Y@dc8569 null JAVA PRACTICAL HANDBOOK Page 20
  • 21.
    21. Call ByValues class ADemo2 { public static void main(String args[]) { int x=10; System.out.println("X :"+x); A a1=new A(); a1.incr(x); System.out.println("X :"+x); } }c lass A { void incr(int x) { x++; System.out.println("X :"+x); } } X :10 X :11 X :10 JAVA PRACTICAL HANDBOOK Page 21
  • 22.
    22. Call ByRef class BDemo14 { public static void main(String args[]) { V v1=new V(); System.out.println("X :"+v1.x); A a1=new A(); a1.incr(v1); System.out.println("X :"+v1.x); } }c lass A { void incr(V v1) { v1.x++; System.out.println("X :"+v1.x); } }c lass V { int x=10; } X :10 X :11 X :11 JAVA PRACTICAL HANDBOOK Page 22
  • 23.
    23. Call byvalues class BDemo15 { public static void main(String args[]) { int x=10, y=20; System.out.println(x+" "+y); A a1=new A(); a1.change(x,y); System.out.println(x+" "+y); } }c lass A { void change(int x, int y) { int z; z=x; x=y; y=z; System.out.println(x+" "+y); } } 10 20 20 10 10 20 JAVA PRACTICAL HANDBOOK Page 23
  • 24.
    24. Static variables class A { int a; int b; } class BDemo16 { public static void main(String args[]) { A a1=new A(); a1.a=10; a1.b=20; System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); A a2=new A(); a2.a=100; a2.b=200; System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); } } Object a1 a :10 b :20 Object a1 a :10 b :20 JAVA PRACTICAL HANDBOOK Page 24
  • 25.
    25. class A { int a; static int b; } class BDemo17 { public static void main(String args[]) { A a1=new A(); a1.a=10; a1.b=20; System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); A a2=new A(); a2.a=100; a2.b=200; System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); } } Object a1 a :10 b :20 Object a1 a :10 b :200 JAVA PRACTICAL HANDBOOK Page 25
  • 26.
    26. class A { int a; static int b; } class BDemo18 { public static void main(String args[]) { A a1=new A(); a1.a=10; a1.b=20; System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); A a2=new A(); a2.a=100; a2.b=200; System.out.println("Object a1 a :"+a1.a+" b :"+a1.b); System.out.println("Object a2 a :"+a2.a+" b :"+a2.b); a1.a=10000; a1.b=20000; System.out.println("Object a2 a :"+a2.a+" b :"+a2.b); A a3=new A(); System.out.println("Object a3 a :"+a3.a+" b :"+a3.b); A.b=2000000;// System.out.println("a1.b :"+a1.b+" a2.b :"+a2.b+" a3.b :"+a3.b); } } Object a1 a :10 b :20 Object a1 a :10 b :200 Object a2 a :100 b :200 Object a2 a :100 b :20000 Object a3 a :0 b :20000 a1.b :2000000 a2.b :2000000 a3.b :2000000 JAVA PRACTICAL HANDBOOK Page 26
  • 27.
    27. Static methods class A { void m1() { System.out.println("m1"); }s tatic void m2() { System.out.println("m2"); } } class BDemo19 { public static void main(String args[]) { A ob=new A(); ob.m1(); A.m2();// without creating object can call method } } m1 m2 JAVA PRACTICAL HANDBOOK Page 27
  • 28.
    28. class A { int x=10; static int y=20; void m1() { System.out.println(x); System.out.println(y); } } class BDemo20 { public static void main(String args[]) { new A().m1(); } } 10 20 JAVA PRACTICAL HANDBOOK Page 28
  • 29.
    29. class A { int x=10; static int y=20; void m1() { System.out.println(this.x); System.out.println(this.y); } } class BDemo21 { public static void main(String args[]) { new A().m1(); } } 10 20 JAVA PRACTICAL HANDBOOK Page 29
  • 30.
    30. Object /static initializer class A { static { System.out.print("1 "); }{ System.out.print("2 "); }A () { System.out.print("3 "); }v oid m1() { System.out.print("4 "); }s tatic void m2() { System.out.print("5 "); } } class BDemo22 { public static void main(String args[]) { new A(); A.m2(); } } 1 2 3 5 JAVA PRACTICAL HANDBOOK Page 30
  • 31.
    31. class A { int a; void printA() { System.out.println("a :"+a); } }c lass B extends A { int b; void printB() { System.out.println("b :"+b); }v oid printAB() { System.out.println("a+b :"+(a+b)); }v oid callAB() { printA(); printB(); } }c lass BDemo23 { public static void main(String args[]) { B b1=new B(); b1.a=10; b1.b=20; b1.printA(); b1.printB(); b1.printAB(); b1.callAB(); } } a :10 b :20 a+b :30 a :10 b :20 JAVA PRACTICAL HANDBOOK Page 31
  • 32.
    32. super classConstructor class A { int a; A() { System.out.println("A()"); }A (int i) { System.out.println("A(int)"); }v oid printA() { System.out.println("a :"+a); } }c lass B extends A { int b; B() { System.out.println("B()"); }B (int i) { System.out.println("B(int)"); }v oid printB() { System.out.println("b :"+b); }v oid printAB() { System.out.println("a+b :"+(a+b)); }v oid callAB() { printA(); printB(); } }c lass BDemo24 { public static void main(String args[]) { B b1=new B(); B b2=new B(100); } JAVA PRACTICAL HANDBOOK Page 32
  • 33.
    } A() B() A() B(int) 33. class A { int a; A() { System.out.println("A()"); }A (int i) { System.out.println("A(int)"); }v oid printA() { System.out.println("a :"+a); } } class B extends A { int b; B() { super(); System.out.println("B()"); }B (int i) { super(); System.out.println("B(int)"); }v oid printB() { System.out.println("b :"+b); }v oid printAB() { System.out.println("a+b :"+(a+b)); }void callAB(){ JAVA PRACTICAL HANDBOOK Page 33
  • 34.
    printA(); printB(); } }c lass BDemo25 { public static void main(String args[]) { B b1=new B(); B b2=new B(100); } } A() B() A() B(int) JAVA PRACTICAL HANDBOOK Page 34
  • 35.
    34. class A { int a; A() { System.out.println("A()"); }A (int i) { System.out.println("A(int)"); }v oid printA() { System.out.println("a :"+a); } }c lass B extends A { int b; B() { super();// System.out.println("B()"); }B (int i) { super(i);//super(100); System.out.println("B(int)"); }v oid printB() { System.out.println("b :"+b); }v oid printAB() { System.out.println("a+b :"+(a+b)); }v oid callAB() { printA(); printB(); } }c lass BDemo26 { public static void main(String args[]) { B b1=new B(); JAVA PRACTICAL HANDBOOK Page 35
  • 36.
    B b2=new B(100); } } A() B() A(int) B(int) JAVA PRACTICAL HANDBOOK Page 36
  • 37.
    35. class A { int a; A() { System.out.println("A()"); }A (int i) { System.out.println("A(int)"); }v oid printA() { System.out.println("a :"+a); } }c lass B extends A { int b; B() { super();// System.out.println("B()"); }B (int i) { super(i);//super(100); System.out.println("B(int)"); }v oid printB() { System.out.println("b :"+b); }v oid printAB() { System.out.println("a+b :"+(a+b)); }v oid callAB() { printA(); printB(); } }c lass BDemo27 { public static void main(String args[]) { A a1; JAVA PRACTICAL HANDBOOK Page 37
  • 38.
    a1=new B(); //Bb1=new A();//Error a1.a=10; // a1.b=20; Error a1.printA(); /* a1.printB();//Error a1.printAB();//Error a1.callAB();//Error */ } } A() B() a :10 JAVA PRACTICAL HANDBOOK Page 38
  • 39.
    36. Method Overriding class A { int a; void printA() { System.out.println("a :"+a); }v oid print() { System.out.println("A.print"); } } class B extends A { int b; void printB() { System.out.println("b :"+b); }v oid printAB() { System.out.println("a+b :"+(a+b)); }v oid callAB() { printA(); printB(); }v oid print() { System.out.println("B.print"); } } class BDemo28 { public static void main(String args[]) { A a1=new B(); a1.print(); } } B.print JAVA PRACTICAL HANDBOOK Page 39
  • 40.
    37. class Vehicle { void park() {} }c lass Car extends Vehicle { void park() { System.out.println("Car park"); } }c lass Bus extends Vehicle { void park() { System.out.println("Bus park"); } }c lass MB extends Vehicle { void park() { System.out.println("MB park"); } }c lass BDemo29 { public static void main(String argsp[]) { Vehicle ob; ob=new Car(); ob.park(); //print "Car park" ob=new Bus(); ob.park(); //print "Bus park" ob=new MB(); ob.park(); //print "MB park" } } Car park Bus park MB park JAVA PRACTICAL HANDBOOK Page 40
  • 41.
    38. class A { static { System.out.print("1 "); }{ System.out.print("2 "); }A () { System.out.print("3 "); }s tatic void mA() { System.out.print("4 "); } }c lass B extends A { static { System.out.print("5 "); }{ System.out.print("6 "); }B () { System.out.print("7 "); }s tatic void mB() { System.out.print("8 "); } }c lass BDemo30 { public static void main(String args[]) { new B(); } } 1 5 2 3 6 7 JAVA PRACTICAL HANDBOOK Page 41
  • 42.
    39. class A { static { System.out.print("1 "); }{ System.out.print("2 "); }A () { System.out.print("3 "); }s tatic void mA() { System.out.print("4 "); } }c lass B extends A { static { System.out.print("5 "); }{ System.out.print("6 "); }B () { System.out.print("7 "); }s tatic void mB() { System.out.print("8 "); } }c lass BDemo31 { public static void main(String args[]) { B.mA(); //Prints 1 4 } } 1 4 JAVA PRACTICAL HANDBOOK Page 42
  • 43.
    40. Way ofinvoking "super()" and "this()" class A { A(int i) { System.out.println("A(int) :"+i); } }c lass B extends A { B(int i) { super(i); System.out.println("B(int) :"+i); } }c lass BDemo32 { public static void main(String args[]) { new B(100); } } A(int) :100 B(int) :100 JAVA PRACTICAL HANDBOOK Page 43
  • 44.
    41. class A { A(int i) { System.out.println("A(int) :"+i); }A (int i, int j) { System.out.println("A(int,int) :"+i+" "+j); } }c lass B extends A { B(int i) { super(100); System.out.println("B(int) :"+i); }B (int i, int j ) { super(i, j); System.out.println("B(int, int) :"+i+" "+j); } }c lass BDemo33 { public static void main(String args[]) { new B(100,200); } } A(int,int) :100 200 B(int, int) :100 200 JAVA PRACTICAL HANDBOOK Page 44
  • 45.
    42. "calling this" class A { int a=100; A() { this(1); }A (int i) { a=i; } }c lass B extends A { int b=200; B(){ this(1); }B (int i) { super(i); b=i; }B (int i, int j) { super(i); b=j;// }v oid printAB() { System.out.println("a b :"+a+" "+b); } }c lass BDemo34 { public static void main(String args[]) { B b1=new B(); b1.printAB(); B b2=new B(10); b2.printAB(); B b3=new B(100,200); b3.printAB(); } } JAVA PRACTICAL HANDBOOK Page 45
  • 46.
    a b :11 a b :10 10 a b :100 200 JAVA PRACTICAL HANDBOOK Page 46
  • 47.
    43. "this" VS"super" class A { int a=100; A() { this(1); }A (int i) { a=i; } }c lass B extends A { int b=200; B() { this(1); }B (int i) { super(i); b=i; }B (int i, int j) { super(i); b=j;// }v oid printAB() { System.out.println("a b :"+a+" "+b); } }c lass BDemo35 { public static void main(String args[]) { B b1=new B(); b1.printAB(); B b2=new B(10); b2.printAB(); B b3=new B(100,200); b3.printAB(); } } JAVA PRACTICAL HANDBOOK Page 47
  • 48.
    a b :11 a b :10 10 a b :100 200 JAVA PRACTICAL HANDBOOK Page 48
  • 49.
    44. class A { void print() { System.out.println("A.print"); } }c lass B extends A { void print() { System.out.println("B.print"); } }c lass BDemo36 { public static void main(String args[]){ B b1=new B(); b1.print(); //prints "B.print" } } B.print JAVA PRACTICAL HANDBOOK Page 49
  • 50.
    45. class A { void print() { System.out.println("A.print"); } }c lass B extends A { void print() { System.out.println("B.print"); } }c lass BDemo37 { public static void main(String args[]) { A a1=new B(); a1.print();//print "B.print" } } B.print JAVA PRACTICAL HANDBOOK Page 50
  • 51.
    46. class A { int a=100; }c lass B extends A { int a=200; }c lass BDemo38 { public static void main(String args[]) { B b1=new B(); int x=b1.a; System.out.println(x);//print "200" } } 200 JAVA PRACTICAL HANDBOOK Page 51
  • 52.
    47. class A { int a=100; }c lass B extends A { int a=200; }c lass BDemo39 { public static void main(String args[]) { A a1=new B(); int x=a1.a; System.out.println(x);//print "100" } } 100 JAVA PRACTICAL HANDBOOK Page 52
  • 53.
    48. class A { int a=100; }c lass B extends A { int a=200; void m() { System.out.println("a :"+a); } }c lass BDemo40 { public static void main(String args[]) { B b1=new B(); b1.m(); //prints "a :200" } } 200 JAVA PRACTICAL HANDBOOK Page 53
  • 54.
    49. super.a classA { int a=100; }c lass B extends A { int a=200; void m() { System.out.println("a :"+super.a); } }c lass BDemo41 { public static void main(String args[]) { B b1=new B(); b1.m(); } } a :100 50. class A { int a=100; }c lass B extends A { int a=200; }c lass C extends B { int a=300; void m() { System.out.println("a :"+a); } }c lass BDemo42 { public static void main(String args[]) { C c1=new C(); c1.m(); } JAVA PRACTICAL HANDBOOK Page 54
  • 55.
    } a :300 JAVA PRACTICAL HANDBOOK Page 55
  • 56.
    51. class A { void print() { System.out.println("A.print"); } }c lass B extends A { void print() { System.out.println("B.print"); } }c lass C extends B { void print() { System.out.println("C.print"); }v oid m() { print(); } }c lass BDemo43 { public static void main(String args[]) { C c1=new C(); c1.m(); } } C.print JAVA PRACTICAL HANDBOOK Page 56
  • 57.
    52. class A { void print() { System.out.println("A.print"); } }c lass B extends A { void print() { System.out.println("B.print"); } }c lass C extends B { void print() { System.out.println("C.print"); }v oid m() { super.print(); } }c lass BDemo44 { public static void main(String args[]) { C c1=new C(); c1.m(); } } B.print JAVA PRACTICAL HANDBOOK Page 57
  • 58.
    53. class A { A() { print(); }v oid print() { System.out.println("A.print"); } }c lass B extends A { void print() { System.out.println("B.print"); } } class BDemo45 { public static void main(String args[]) { new B(); } } B.print JAVA PRACTICAL HANDBOOK Page 58
  • 59.
    54. class A { int a=100; A() { print(); }v oid print() { System.out.println("A.print "+a); } }c lass B extends A { int a=200; void print() { System.out.println("B.print "+a); } } class BDemo46 { public static void main(String args[]) { new B(); } } B.print 0 JAVA PRACTICAL HANDBOOK Page 59
  • 60.
    55. class A { int a=100; A() { print(); }v oid print() { System.out.println("A.print "+a); } }c lass B extends A { //int a=200; void print() { System.out.println("B.print "+a); } } class BDemo47 { public static void main(String args[]) { new B(); } } B.print 100 JAVA PRACTICAL HANDBOOK Page 60
  • 61.
    56. class A { int a=100; A() { print(); }v oid print() { System.out.println("A.print "+a); } }c lass B extends A { static int a=200; void print() { System.out.println("B.print "+a); } } class BDemo48 { public static void main(String args[]) { new B(); } } B.print 200 JAVA PRACTICAL HANDBOOK Page 61
  • 62.
    57. class A { A() { print(); }s tatic void print() { System.out.println("A.print "); } }c lass B extends A { static void print() { System.out.println("B.print "); } } class BDemo49 { public static void main(String args[]) { new B(); } } A.print JAVA PRACTICAL HANDBOOK Page 62
  • 63.
    58. Private methods class A { void m1() { System.out.println("A.m1"); }p rivate void m2() { System.out.println("A.m2"); }v oid mA() { m1(); m2(); } } class BDemo50 { public static void main(String asrgs[]) { new A().mA(); new A().m1(); /* new A().m2(); error: m2() has private access in A new A().m2(); */ } } A.m1 A.m2 A.m1 JAVA PRACTICAL HANDBOOK Page 63
  • 64.
    59. class A { A() { print(); }p rivate void print() { System.out.println("A.print "); } }c lass B extends A { void print() { System.out.println("B.print "); } } class BDemo51 { public static void main(String args[]){ new B(); } } A.print JAVA PRACTICAL HANDBOOK Page 64
  • 65.
    60. class A { X print() { X x1=new X(); System.out.println("X.print "); return x1; } }c lass B extends A { Y print() { Y y1=new Y(); System.out.println("Y.print "); return y1; } } class BDemo52 { public static void main(String args[]) { A a1=new B(); X ob= a1.print(); } }c lass X{} class Y extends X {} Y.print JAVA PRACTICAL HANDBOOK Page 65
  • 66.
    61. class "Object" class A {}c lass BDemo53 { public static void main(String args[]) { A a1=new A(); System.out.println(a1.toString()); System.out.println(a1.hashCode()); } } A@10385c1 17008065 JAVA PRACTICAL HANDBOOK Page 66
  • 67.
    62. class Aextends Object {}c lass BDemo54 { public static void main(String args[]) { A a1=new A(); System.out.println(a1.toString()); System.out.println(a1.hashCode()); } } A@10385c1 17008065 63. Demonstrate methods "toString()" class A { int a; A(int i) { a=i; } }c lass BDemo55 { public static void main(String args[]) { A a1=new A(100); System.out.println(a1.toString()); System.out.println(a1); } } A@10385c1 A@10385c1 JAVA PRACTICAL HANDBOOK Page 67
  • 68.
    64. class A { int a; A(int i) { a=i; }p ublic String toString() { return ""+a; } }c lass BDemo56 { public static void main(String args[]) { A a1=new A(100); System.out.println(a1.toString()); System.out.println(a1); } } 100 100 JAVA PRACTICAL HANDBOOK Page 68
  • 69.
    65. class A { public String toString() { return "class A"; } }c lass B extends A { public String toString() { return "class B"; } }c lass C extends B { public String toString() { return "class C"; } }c lass BDemo57 { public static void main(String args[]) { Object ob; ob=new A(); System.out.println(ob); ob=new B(); System.out.println(ob); ob=new C(); System.out.println(ob); } } class A class B class C JAVA PRACTICAL HANDBOOK Page 69
  • 70.
    66. Demonstrate methods"equals(Object ob)" of class Object class A { int a; A(int i) { a=i; } }c lass BDemo58 { public static void main(String args[]) { A a1=new A(100); A a2=new A(100); A a3=new A(200); A a4=a1; System.out.println(a1==a2); System.out.println(a1==a3); System.out.println(a1==a4); } } false false true JAVA PRACTICAL HANDBOOK Page 70
  • 71.
    67. class A { int a; A(int i) { a=i; } }c lass BDemo59 { public static void main(String args[]) { A a1=new A(100); A a2=new A(100); A a3=new A(200); A a4=a1; System.out.println(a1.equals(a2)); System.out.println(a1.equals(a3)); System.out.println(a1.equals(a4)); } } false false true JAVA PRACTICAL HANDBOOK Page 71
  • 72.
    68. class A { int a; A(int i) { a=i; }p ublic boolean equals(Object ob) { A a1=(A)ob; return a1.a==this.a ; } }c lass BDemo60 { public static void main(String args[]) { A a1=new A(100); A a2=new A(100); A a3=new A(200); A a4=a1; System.out.println(a1.equals(a2)); System.out.println(a1.equals(a3)); System.out.println(a1.equals(a4)); } } true false true JAVA PRACTICAL HANDBOOK Page 72
  • 73.
    69. Methods Overloadingfor class Type class BDemo61 { static void m(A a) { System.out.println("m(A)"); }s tatic void m(B a) { System.out.println("m(B)"); }s tatic void m(C a) { System.out.println("m(C)"); }p ublic static void main(String args[]) { A a1=new A(); B b1=new B(); C c1=new C(); BDemo61.m(a1); BDemo61.m(b1); BDemo61.m(c1); } }c lass A{} class B{} class C{} m(A) m(B) m(C) JAVA PRACTICAL HANDBOOK Page 73
  • 74.
    70. class BDemo62 { static void m(A a) { System.out.println("m(A)"); }s tatic void m(B a) { System.out.println("m(B)"); }p ublic static void main(String args[]) { A a1=new A(); B b1=new B(); C c1=new C(); BDemo62.m(a1); BDemo62.m(b1); BDemo62.m(c1); } }c lass A{} class B{} class C extends B{} m(A) m(B) m(B) JAVA PRACTICAL HANDBOOK Page 74
  • 75.
    71. class BDemo63 { static void m(A a) { System.out.println("m(A)"); }s tatic void m(B a) { System.out.println("m(B)"); }p ublic static void main(String args[]) { A a1=new A(); B b1=new B(); C c1=new C(); BDemo63.m(a1); BDemo63.m(b1); BDemo63.m(c1); } }c lass A{} class B extends A{} class C extends B{} m(A) m(B) m(B) JAVA PRACTICAL HANDBOOK Page 75
  • 76.
    72. class BDemo64 { static void m(Object a) { System.out.println("m(Object)"); } public static void main(String args[]) { A a1=new A(); B b1=new B(); C c1=new C(); BDemo64.m(a1); BDemo64.m(b1); BDemo64.m(c1); } }c lass A{} class B extends A{ } class C extends B{} m(Object) m(Object) m(Object) JAVA PRACTICAL HANDBOOK Page 76
  • 77.
    73. Abstract Methods abstract class Vehicle { abstract void park(); }c lass BDemo65 { public static void main(String args[]) { Vehicle ob; ob=new Car(); ob.park(); ob=new Bus(); ob.park(); ob=new MB(); ob.park(); } }c lass Car extends Vehicle { void park() { System.out.println("Car park"); } }c lass Bus extends Vehicle { void park() { System.out.println("Bus park"); } }c lass MB extends Vehicle { void park() { System.out.println("MB park"); } } Car park Bus park MB park JAVA PRACTICAL HANDBOOK Page 77
  • 78.
    74. Creating aninner class object class A { int i=100; void m() { System.out.print(i); }c lass Inner { int j=10; void mn() { System.out.print(i+" "); System.out.print(j); } } }c lass DemoA2 { public static void main(String args[]) { A ob=new A(); A.Inner inOb=ob.new Inner(); inOb.mn(); } } 100 10 JAVA PRACTICAL HANDBOOK Page 78