为什么要使用 setter 和 getter 方法来定义某事？

Question

*Using Setter and Getter

class sum {
  int a;
  int b;
  int c;
  public void setSum(int a, int b) {
    c = a + b;
  } 
  public int getSum() {
    return c;
    }
  public static void main(String[] args) {
    sum s = new sum();
    s.setSum(10,7);
    System.out.println("Sum: " + s.getSum());
    }
  }

*Using just only one method (getter)

class sum1 {
  int a;
  int b;
  int c;
  public int getSum(int a, int b) {
    c = a+b;
    return c;
    }
  public static void main(String[] args) {
    sum1 s1 = new sum1();
    System.out.println("Sum: " + s1.getSum(7,10));
    }
  }

I would like to know why the teacher encouraged me to use Setter and Getter when both coding ways result the same (17)

What specific reason lies behind using Setter and Getter?

Answer 1

Like visibleman said, they're not the same thing. They do what their names say, they set values and get values. Although you may not see the use of them in a small program. Their uses are noticeable in a large application where you have to modularise your code and you want to GET a value from some other class from somewhere. You wouldn't want that method to be 'SET'ting that value to something else while you're 'GET'ting the value. Do you understand?