public class HelloWorld{

    public static void main(String[] args) {

    int one = 10 ;

        int two = 20 ;

        int three=0;

        three=one+two;

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

        three+=one;

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

        three-=one;

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

        three*=one;

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

        three/=one;

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

        three%=one;

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

}

}

拼写错了 System

public class HelloWorld{

    public static void main(String[] args) {

    int one = 10 ;

        int two = 20 ;

        int three=0;

        three=one+two;

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

        three+=one;

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

        three-=one;

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

        three*=one;

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

        three/=one;

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

        three%=one;

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

}

}