如果我在 java 中对同一个对象调用 new 两次会发生什么?

问题描述

所以说我有一些这样的测试java代码:

So say I have some test java code like this:

class A(){
       int a = 0;
       public A{
             a = 1;
       }
 class B(){
       A object = new A(); //Object one
       A object = new A(); //Object two

我的问题是:在 A 类中，当我在对象上调用 new 运算符两次时会发生什么?它是否创建了一个新对象 A 并销毁了旧对象?还是会出错?它只是重置旧对象吗?

My question is: In class A when I call the new operator on object twice what happens? Does it create a new object A and destroy the old one? Or will it error? Does it just reset the old object?

我已经尝试了几次，但并不真正理解输出.

I have tried this a couple times and don't really understand the output.

推荐答案

它是第二个 A 对象.

第一个将在稍后被垃圾回收.

The first will be garbage collected sooner later.

注意，你也可以这样做

new A();
new A();

不将它们存储在变量中.它完全有效，将被执行.

without storing them in a variable. It's perfectly valid, and will be executed.

还要注意

A obj1 = new A();
A obj2 = obj1;

不复制对象，但它是对同一对象的引用.显然，您也可以有 0 个引用.

does not copy the object, but it's a reference to the same object. You can also have 0 references, obviously.

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