Question

我有一个LabelTextField类，它表示，它创建一个标签，后跟文本字段。我希望这个类充当JTextField，即在添加动作侦听器时响应actionPerformed。我正在使用LabelTextField添加一个动作侦听器，因此该类中的JTextField需要在LabelTextField对象名而不是JTextField对象名上接收回调和转发。

我已经展示了一个简单的JTextField及其工作原理，LabelTextField也在那里以及我希望如何使用它。

我提供了我想要做的代码片段。

我遇到这种类型的回调问题，详细信息会很有用。

//

class C_one extends JPanel
{

       private JTextField      mjtfOne;
       private LabelTextField  m_nameFind;

       public C_one ()
       {
          setLayout(new FlowLayout());

          mjtfOne = new JTextField(20);
          mjtfOne.addActionListener(this);

          m_nameFind = new LabelTextField("Name", 20);
          m_nameFind.addActionListener(this);

          add(mjtfOne);
          add(m_nameFind);

       }

       // This is called when return is pressed in either object.
       public void actionPerformed(ActionEvent ae) 
       {
          // This works.
          if (ae.getSource() == mjbnOne) {
             System.out.println("Text field one!");

          // ****** This doesn't work. *****
          } else if (ae.getSource() == m_nameFind) {
             System.out.println("Label Text Field name");
          }
       }

}

// //这将创建标签和文本字段作为窗口小部件。 class LabelTextField扩展了JPanel {

   private  JTextField     mjtf;
   private ActionListener  mal;


   public LabelTextField(String label, int textfieldWidth)
   {
      setLayout(new FlowLayout());

      JLabel lbl = new JLabel(label);
      add(lbl);

      mjtf = new JTextField(textfieldWidth);    
      add(mjtf);    
   }

   // The caller of this class will call this as he would for
   // JTextField.
   public void addActionListener(ActionListener al) 
   {
      mjtf.addActionListener(this);
      mal = al;     
   }

   // This will receive the return from JTextField and needs
   // to forward this on to calling class with caller object
   // not mjtf. 
   //
   // Problem: I can not figure out how to save caller object 
   // name so when this is called I can forward it on just like 
   // what JTextField would have done, ie caller can use 
   // ae.getSource() == m_nameFind.
   public void actionPerformed(ActionEvent ae) 
   {
      mal.actionPerformed(ae); // This does call the caller.
   }

}

Answer 1

ae.getSource()的值将为mjtf，因为这是生成原始ActionEvent的组件。如果您希望事件来源为m_nameFind，即您的自定义LabelTextField对象，则需要手动设置：

  public void actionPerformed(ActionEvent ae) 
  {
    ae.source=this; // this makes it look like the LabelTextField generated the event
    mal.actionPerformed(ae); 
  }

这是你想要做的吗？

-

修改

谢谢@Madprogrammer ..也许你应该像这样重新创建ActionEvent

  public void actionPerformed(ActionEvent ae) 
  {
      mal.actionPerformed(new ActionEvent(this, ae.getID(),
         ae.getCommand(), ae.getWhen(), ae.getModifiers() )); 
  }

Answer 2

由于无法更改ActionEvent的源代码，因此需要创建一个新的ActionEvent：

public void actionPerformed(ActionEvent e)
{
    e = new ActionEvent(
        this,
        ActionEvent.ACTION_PERFORMED,
        e.getActionCommand(),
        e.getWhen(),
        e.getModifiers());

    mal.actionPerformed(e);
}

actionlistener回调到另一个类

2 个答案: