类的对象作为类中的实例变量 [英] Object of the class as instance variable inside the class

问题描述

可能重复：

Possible Duplicate:
How can a class have a member of its own type, isnt this infinite recursion?

代码：

public class Test2{
    private Test2 subject = new Test2(); //Create Test2 object in Test2
    private int num;
}

问题：

1. 为什么Java允许执行上述代码，但C ++不执行？

1. Why does Java permit the above code to be executed, but C++ doesn't?

上面创建无限多个对象？由于 Test2 本身包含 Test2 对象，其中还包含 Test2

Does the code above create infinite number of objects? Since Test2 itself contains a Test2 object which again contains a Test2 object which itself has a Test2 object and so on.

推荐答案

问题2 - 如果你运行这个代码，你会得到一个StackOverflowException =>是的，它会创建无限数量的对象（试试...）

Re question 2 - if you run this code, you get a StackOverflowException => Yes it creates an inifinite number of objects (well it tries...)

public class Test2 {

    private Test2 subject = new Test2(); //Create Test2 object in Test2

    public static void main(String[] args) throws Exception {
        Test2 t = new Test2();
    }
}

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