java - String 在 Java 中如何成为引用类型？

Question

我知道类是引用类型，例如我创建了以下类:

class Class {

String s = "Hello";

public void change() {
    s = "Bye";
} }

通过以下代码，我明白 Class是引用类型:

Class c1 = new Class(); 
Class c2 = c1; //now has the same reference as c1

System.out.println(c1.s); //prints Hello
System.out.println(c2.s); //prints Hello

c2.change(); //changes s to Bye

System.out.println(c1.s); //prints Bye
System.out.println(c2.s); //prints Bye

现在我想用字符串做同样的事情，但这是行不通的。我在这里做错了什么？:

String s1 = "Hello";
String s2 = s1; //now has the same reference as s1 right?

System.out.println(s1); //prints Hello
System.out.println(s2); //prints Hello

s2 = "Bye"; //now changes s2 (so s1 as well because of the same reference?) to Bye

System.out.println(s1); //prints Hello (why isn't it changed to Bye?)
System.out.println(s2); //prints Bye

Answer 1

在第一种情况下，您正在调用被引用对象的方法，因此被引用对象会发生变化，而不是 2 个引用:



在第二种情况下，您将一个新对象分配给引用本身，然后指向该新对象: