使用线程时出现StackOverflowError

Question

我正在研究一个程序，这是一个具有用户界面的抛射运动模拟。我得到一个StackOverflow错误，它似乎发生在我试图为我的按钮和文本字段创建我的动作监听器。我知道stackoverflow错误与永远不会退出的递归有关，但我没有在我的代码中看到它发生的地方。

我决定在我的程序中使用线程，因为我所拥有的耗时的活动减慢了程序。所以我有一个线程来处理模拟的所有计算。

代码很长，但这里是它的结构。

 public class SimulationGUI implements ActionListener, Runnable
 {
      //Create object references for window, panels, text fields, buttons, and labels. 
      SimulationGUI() 
      {
           //Here I instantiate all my buttons, textfields, labels, 
           //and basically set up the user interface.
           createListeners(); //This calls a method that creates my action listeners
      }   
      public void actionPerformed(ActionEvent e)
       {
           Thread thread = new Thread(this);
           thread.start();  // this calls the method run()
      }
      public void run()
      {
           //Here, I get the text for the variables  
           //calculations are performed for the projectile motion
           //I also edit three top level text fields using .setText()
      } 
      public void createListeners()
      {
           //Add action listeners for each text field
           ActionListener angleList = new SimulationGUI(); 
           angleText.addActionListener(angleList); 
           ..... 
      } 
      public static void main(String[] args)
      {
           new SimulationGUI(); 
      }
 }

我猜我将不得不在一个新的线程中创建和添加动作监听器，但我不完全确定。以下是我得到的错误:

 Exception in thread "main" java.lang.StackOverflowError
     at java.awt.Insets.<init>(Unknown Source)
     at sun.awt.windows.WToolkit.getScreenInsets(Native Method)
     at sun.awt.windows.WToolkit.getScreenInsets(Unknown Source)
     at java.awt.Window.init(Unknown Source)
     at java.awt.Window.<init>(Unknown Source)
     at java.awt.Frame.<init>(Unknown Source)
     at javax.swing.JFrame.<init>(Unknown Source)
     at SimulationGUI.<init>(SimulationGUI.java:24)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.<init>(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.<init>(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.<init>(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.<init>(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.<init>(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.<init>(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
 .....

Answer 1

是的，你得到了一个无限循环。这是导致问题的代码部分:

SimulationGUI() 
{
    createListeners();
}
public void createListeners()
{
    ActionListener angleList = new SimulationGUI();
    angleText.addActionListener(angleList);
}

知道怎么了吗?这两个方法都无条件地相互调用，并且在剩余的时间内(或者至少在堆栈满之前)都会这样做。证据在堆栈跟踪中:

at SimulationGUI.<init>(SimulationGUI.java:24)
at SimulationGUI.createListeners(SimulationGUI.java:211)
at SimulationGUI.<init>(SimulationGUI.java:124)
at SimulationGUI.createListeners(SimulationGUI.java:211)
at SimulationGUI.<init>(SimulationGUI.java:124)
at SimulationGUI.createListeners(SimulationGUI.java:211)
at SimulationGUI.<init>(SimulationGUI.java:124)
at SimulationGUI.createListeners(SimulationGUI.java:211)
at SimulationGUI.<init>(SimulationGUI.java:124)
at SimulationGUI.createListeners(SimulationGUI.java:211)
at SimulationGUI.<init>(SimulationGUI.java:124)
at SimulationGUI.createListeners(SimulationGUI.java:211)
at SimulationGUI.<init>(SimulationGUI.java:124)
at SimulationGUI.createListeners(SimulationGUI.java:211)

看到这些方法是如何相互调用的了吗?您可能想要更像这样的内容:

SimulationGUI() 
{
    createListeners();
}
public void createListeners()
{
    angleText.addActionListener(this);
}

Answer 2

Exception in thread "main" java.lang.StackOverflowError
     at java.awt.Insets.(Unknown Source)
     at sun.awt.windows.WToolkit.getScreenInsets(Native Method)
     at sun.awt.windows.WToolkit.getScreenInsets(Unknown Source)
     at java.awt.Window.init(Unknown Source)
     at java.awt.Window.(Unknown Source)
     at java.awt.Frame.(Unknown Source)
     at javax.swing.JFrame.(Unknown Source)
     at SimulationGUI.(SimulationGUI.java:24)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
     at SimulationGUI.(SimulationGUI.java:124)
     at SimulationGUI.createListeners(SimulationGUI.java:211)
 

从你的代码和堆栈转储来看，我看到的直接问题是:每次你的SimulationGUI构造函数被调用时，就会调用createlistener，这会创建另一个SimulationGUI，这个SimulationGUI会调用createlistener，然后创建另一个SimulationGUI等等。除此之外，每次调用createlistener时，都会启动一个新线程。