这种方法如何运作? [英] How does this method work?

问题描述

我经常遇到这种注册动作监听器的方法.

I have often come across this way of registering an action listener.

尽管我最近一直在使用这种方法，但是我不明白这种方法的作用和原因

Though I have been using this method recently but I don't understand how's and why's of this

这里是一个:{

submit=new JButton("submit");
submit.addActionListener(new ActionListener(){       // line 1

  public void actionPerformed(ActionEvent ae) {
    submitActionPerformed(ae);
  }
}); //action listener added

}调用的方法:

public void submitActionPerformed(ActionEvent ae) {

    // body

}

在这种方法中，我不需要实现ActionListener.为什么?

In this method, I don't need to implement ActionListener. Why?

另外，请解释标为第1行的代码的作用.

Also, please explain what the code labeled as line 1 does.

请清楚说明这两个摘要.

Please explain the 2 snippets clearly.

推荐答案

从技术上讲，您确实实现了ActionListener.当您调用 addActionListener 时:

You technically did implement ActionListener. When you called addActionListener:

submit.addActionListener(
 new ActionListener(){
  public void actionPerformed(ActionEvent ae) {
   submitActionPerformed(ae); 
   } 
  });

您创建了 匿名类的实例> 或没有名称的实现 ActionListener 的类.

You created an instance of an anonymous class, or a class that implements ActionListener without a name.

换句话说，上面的代码段基本上就像我们使用

In other words, the snippet above is essentially like if we did this with a local inner class:

class MyActionListener implements ActionListener
{
 public void actionPerformed(ActionEvent ae)
 {
  submitActionPerformed(ae);
 }
}

submit.addActionListener(new MyActionListener());

在您的示例中，匿名类仅调用您的成员方法之一 submitActionPerformed .这样，您的方法的名称可以比 actionPerformed 更具描述性，而且还可以在ActionListener之外的类中使用它.

For your example, the anonymous class just calls one of your member methods, submitActionPerformed. This way, your method can have a slightly more descriptive name than actionPerformed, and it also makes it usable elsewhere in your class besides the ActionListener.

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