hexadecimal (base 16) integer literals.

A hexadecimal constant starts with a leading zero-x, (0x or 0X).

The range of a hexadecimal digit is 0 to 15, so A through F (or a through f ) are substituted for 10 through 15.

In the following example, we define an integer with hexadecimal integer literal.

public class Main{
  public static void main(String[] argv){
    int f = 0XFFFFF;

    System.out.println(f);
    
  }
}

The code above prints out the following:

1048575