public class HelloWorld{

    public static void main(String[] args) {

    int one = 10 ;

        int two = 20 ;

        int three = 0 ;

        three = one + two;  //three = 10+20，所以three是30；

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

        three += one ;  //three = 30+10，所以three是40；

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

        three -= one ;  //three = 40-10，所以three是30；

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

        three *= one ;//three = 30*10，所以three是300；

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

        three /= one ;//three = 300/10，所以three是30；

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

        three %= one ; //three = 30%10，所以three是0；

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

}

}