一个String值不会改变问题

Question

 class Ref{
    String temp = "Hello";
}
public class StringProblem {


    public static void main(String[] args) {
        String str1 = "hello";
        System.out.println(str1);//输出"hello"
        change(str1);
        System.out.println(str1);//输出"hello"
        Ref ref = new Ref();
        System.out.println(ref.temp);//输出"Hello"
        change(ref);
        System.out.println(ref.temp);//输出"world"
    }
    public static void change (String str ){
        str = "world";
    }
    public static void change (Ref str ){
        str.temp = "world";
    }
}

为什么str1的值不会修改 ref.temp的值会修改？

Answer 1

自己分析