本地和实例对象创建时的java StackOverflowError [英] java StackOverflowError when local and instance objects creation

问题描述

谁能解释一下为什么这段代码片段给了我 StackOverflowError如果您能解释在 instanceObj 初始化和调用 ObjectTest 构造函数和 java.lang.Object 构造函数时发生了什么，我真的很感激.在我看来 ObjectTest 构造函数循环一遍又一遍.但我不知道确切的原因?所以任何建议...

Hi can anybody please explain me why is this code snippet giving me StackOverflowError I really appreciate if you can explain what is happening when instanceObj initializing and calling ObjectTest constructor and java.lang.Object constructor. It seems to me ObjectTest constructor loop over and over.But I don't know exact reason? So any suggestion...

public class ObjectTest {

  public ObjectTest() {

   }


  ObjectTest instanceObj = new ObjectTest();


  public static void main(String[] args) {

     ObjectTest localObj = new ObjectTest();
   }
}

推荐答案

让我们看看会执行什么:

Let's see what will be executed :

1. main() 创建一个 ObjectTest
的新实例
2. ObjectTest 类有一个字段 instanceObj，它将包含一个 ObjectTest
3. 使用新的 ObjectTest
初始化的 instanceObj
4. 转到第 2 步

1. main() create a new instance of ObjectTest
2. the ObjectTest class has a field instanceObj which will contain an ObjectTest
3. the instanceObj in initialized with a new ObjectTest
4. go to step 2

<小时>

我想你想要更像这样的东西:

---

I think you wanted something more like this :

public class ObjectTest {
    private static ObjectTest instanceObj;

    private ObjectTest() {
    }

    public static ObjectTest getInstance() {
        if (instanceObj != null) {
            instanceObj = new ObjectTest();
        }
        return instanceObj;
    }

    public static void main(String[] args) {

        ObjectTest localObj = ObjectTest.getInstance();
    }
}

或者这个:

public class ObjectTest {
    private static final ObjectTest instanceObj = new ObjectTest();

    private ObjectTest() {
    }

    public static ObjectTest getInstance() {
        return instanceObj;
    }

    public static void main(String[] args) {

        ObjectTest localObj = ObjectTest.getInstance();
    }
}

这是单例模式.

关于同一主题:

• 为什么我会收到 StackOverflowError
• Java 类中的循环依赖

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