请问==>符号是什么意思，我的代码出来的结果为何通过不了呢？

public class HelloWorld{

    public static void main(String[] args) {

    int one = 10 ;

        int two = 20 ;

        int three = 0 ;

        int three1 = one + two ;

            System.out.println("three=one+two==>"+three1) ;

        int three2 += one ;

            System.out.println("three+=one==>"+three2) ;

        int three3 -= one ;

            System.out.println("three-=one==>"+three3) ;

        int three4 *= one ;

            System.out.println("three*=one==>"+three4) ;

        int three5 /= one ;

            System.out.println("three/=one==>"+three5) ;

        int three6 %= one ;

            System.out.println("three%=one==>"+three6 ) ;

}

}