Untitled

In java, how would I make a calculation where the greatest number is subtracted by the smaller number?
Math.abs(a - b)

public int sub(int firstNumber, int secondNumber) {
    return Math.max(firstNumber, secondNumber) - Math.min(firstNumber, secondNumber);
}

public int sub(int firstNumber, int secondNumber) {
    return Math.abs(firstNumber - secondNumber);
}

public int sub(int a, int b) {
          if(a > b){
            return a - b;
          }
          else if (b > a) {
            return b - a;
          }
          else return 0;
       }

public int sub(int firstNumber, int secondNumber) {

    if( firstNumber < secondNumber ) {
        int temp = secondNumber;
        secondNumber = firstNumber;
        firstNumber = temp;
    }
    return firstNumber - secondNumber;
}