赋值运算符

public class HelloWorld{
    public static void main(String[] args) {
     int one = 10 ;
        int two = 20 ;
   
        int three=one+two;
        int three+=one;
       System.out.println(three);错误是这个  error: ';' expected
       int three += one ;
                ^
error: not a statement
       int three += one ;
                    ^
2 errors