1-4 decimal representation and conversion

Hexadecimal said

• Octal and hexadecimal representation .

public class Main {
    
    public static void main(String[] args){
    
        int x = 0x1f;   //  Hexadecimal 
        System.out.println(x);  // output: 31
        x = 0x1F;
        System.out.println(x);  // output: 31
        x = 070;    //  octal 
        System.out.println(x);  // output: 56

        long y = 0x1f;
        System.out.println(y);  // output: 31
        y = 0x1F;
        System.out.println(y);  // output: 31
        y = 070;
        System.out.println(y);  // output: 56
    }
}

Hexadecimal conversion

• Binary and decimal conversion

public class Main {
    
    public static void main(String[] args){
    
        String str = Long.toBinaryString(7);
        System.out.println(str);    // output: 111
        long x = Long.parseLong("111", 2);
        System.out.println(x);      // output: 7
    }
}

• Octal and decimal conversion

public class Main {
    
    public static void main(String[] args){
    
        String str = Long.toOctalString(63);
        System.out.println(str);    // output: 77
        long x = Long.parseLong("77", 8);
        System.out.println(x);      // output: 31
    }
}

• Hexadecimal and decimal conversion

public class Main {
    
    public static void main(String[] args){
    
        String str = Long.toHexString(15);
        System.out.println(str);    // output: f
        long x = Long.parseLong("1F", 16);
        System.out.println(x);      // output: 31
    }
}