为什么分配的java变量的行为类似于引用？

Question

嗨，我不知道以前是否有人问过这个问题，但这真的很烦人

好的，我有一个叫做Test的类：

public class Test {
    public static Test testObject = new Test(5);//Creates a test object with an initialized value of 5;
    int number;
    public Test(int number){
        this.number = number;
    }
}

当然我的主课

public class Main {
    public static void main(String args[]){
        Test anotherObject = Test.testObject;//this is not a reference right?
        System.out.println(Test.testObject.number);//This prints 5
        anotherObject.number = 50;// changing anotherObject's number. NOT testObject's Number.
        System.out.println(Test.testObject.number);//if that was true this whould of still been 5, but it prints 50!!?? why does testObject's number even change if im not even changing that value?
    }
}

如果我做错了什么，请告诉我，非常感谢

Answer 1

在你的程序中，你有一个Test的实例，你只是每次给它取不同的名字

Test anotherNumber = Test.testObject;

不创建新对象。它只引用同一个对象，你说“每当我写anotherNumber，我实际上是想写Test.testObject”

所以，当你以后改变anotherNumber.number = 50;时，你会：Test.testObject.number = 50;，因此当你打印Test.testObject时，你会看到50

---

编辑：

如果希望能够创建某个对象的副本，可以引入副本构造函数：

public Test(Test original) { 
   this.number = original.number;
}

并与someOtherNumber = new Test(Test.testObject);一起使用