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Primitive Types

Types

  • boolean
  • byte
  • char
  • short
  • int
  • long
  • double

Back to Code

  • Close last project
  • Create New from Template of Command line app

Java Packages

  • A packages is a way to organize Java projects.
  • Consider them folders for now
  • Companies use their domain names reversed

Now we have this code

package com.company;

public class Main {

    public static void main(String[] args) {
	// write your code here
    }
}

Notice

  • Package name at the top
  • Main method already written
  • Look at the side bar and unfold the src file

Back to Code

package com.company;

public class Main {

    public static void main(String[] args) {

        int myValue = 10000;
    }
}

What can we store in an integer?

  • Lets see it in code!
package com.company;

public class Main {

    public static void main(String[] args) {

        int myValue = 10000;
        int myMinValue = Integer.MIN_VALUE;
        int myMaxValue = Integer.MAX_VALUE;

        System.out.println("Integer Minimum value = " + myMinValue);
        System.out.println("Integer Maximum value = " + myMaxValue);
    }
}

Output

Integer Minimum value = -2147483648
Integer Maximum value = 2147483647

Process finished with exit code 0

Wrapper Class

  • Java has wrapper classes for all eight primitive types
  • This gives us ways to perform ops on an int
  • int has Integer

Output

  • Min is -2147483648
  • Max is 2147483647

Let's try and go over the max value

  • Code
package com.company;

public class Main {

    public static void main(String[] args) {

        int myValue = 10000;
        int myMinValue = Integer.MIN_VALUE;
        int myMaxValue = Integer.MAX_VALUE;

        System.out.println("Integer Minimum value = " + myMinValue);
        System.out.println("Integer Maximum value = " + myMaxValue);
        System.out.println("Busted MAX value = " + (myMaxValue + 1));
    }
}

Ouput

Integer Minimum value = -2147483648
Integer Maximum value = 2147483647
Busted MAX value = -2147483648

Process finished with exit code 0

Notice the max went all the way back around to the min int. This is an integer overflow.

Let's do the reverse

package com.company;

public class Main {

    public static void main(String[] args) {

        int myValue = 10000;
        int myMinValue = Integer.MIN_VALUE;
        int myMaxValue = Integer.MAX_VALUE;

        System.out.println("Integer Minimum value = " + myMinValue);
        System.out.println("Integer Maximum value = " + myMaxValue);
        System.out.println("Busted MAX value = " + (myMaxValue + 1));
        System.out.println("Busted MIN value = " + (myMinValue - 1));
    }
}

Output

Integer Minimum value = -2147483648
Integer Maximum value = 2147483647
Busted MAX value = -2147483648
Busted MIN value = 2147483647
  • This triggers an underflow
  • IJ will flag a literal number over the max int
  • int myMaxIntTest = 2147483648; will be red in the IDE
    • Running it will give error java: integer number too large

Note you can use int myMaxIntTest = 2_147_483_647; in java for comma seperation if you want.