这个代码哪里有问题咋一直报错

int one = 10 ;

        int two = 20 ;

        int three = 0 ;

        three=one+two;

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

        three/=one;

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

        three%=one;

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