| Defining Methods | Access Modifiers | Varargs Parameters |
| Method Overloading |
- return type: primitive or object
- method name is Java identifier (same rules as variable names)
- parameters in parameter list are separated by comma
- after throws there can be more than one exception, separated by comma
- method must have a body { }, even if it is empty
public void doNothing() {} // OKprivate |
Method or field can be accessed only within the class in which they are declared |
default(no keyword) |
Method or field can be accessed only within the same package |
protected |
Method or filed can be accessed within the same package and outside the package through child class |
public |
Method of field can be accessed from everywhere in the program |
- Method can accept any number of parameters of the same type
- Two rules to keep in mind:
- a method can have at most one varargs argument
- varargs argument must be the last parameter in the parameter list
public class App{
public static void main(String[] args) {
greet("Hello", "John", "George", "Luke");
// you can pass an array as varargs
String[] allNames = {"Peter", "Paul"};
greet("Hello", allNames);
}
public void greet (String greeting, String... names) {
for (String name : names) {
System.out.println(greeting + ", " + name + "!");
}
}
}Method Overloading means defining multiple methods with the same name in the same class, but with different parameters (type, number, or order). Example:
public class Calculator {
// Overloaded methods
public int add(int a, int b) {
return a + b;
}
public double add(double a, double b) {
return a + b;
}
public int add(int a, int b, int c) {
return a + b + c;
}
}| Rule | Example |
|---|---|
| ✅ Different number of parameters | add(int a) vs add(int a, int b) |
| ✅ Different types of parameters | add(int a, int b) vs add(double a, double b) |
| ✅ Different order of parameters (types) | sum(int a, String b) vs sum(String a, int b) |