求指教，为什么显示全是Three?

public class HelloWorld{

    public static void main(String[] args) {

   int one = 10 ;

        int two = 20 ;

        int three = 0 ;

        int three0 =one+two;

        System.out.println("three");three += one;

        System.out.println("three");three += one;

        System.out.println("three");three -= one;

        System.out.println("three");three *= one;

        System.out.println("three");three /= one;

        System.out.println("three");three %= one;

这样对吗？为什么显示出来全是three?