内部类中的构造方法（实现接口） [英] Constructors in Inner classes (implementing Interfaces)

问题描述

我如何为一个实现接口的内部类编写一个构造函数？我知道我可以做一个全新的课，但我认为有一个方法来做一些这样的事情：

How would I go about writing a constructor for an inner class which is implementing an interface? I know I could make a whole new class, but I figure there's got to be a way to do something along the line of this:

JButton b = new JButton(new AbstractAction() {

    public AbstractAction() {
        super("This is a button");                        
    }


    public void actionPerformed(ActionEvent e) {
        System.out.println("button clicked");
    }
}); 

当我输入它时，它不认识AbstractAction方法作为构造函数（编译器要求返回类型）。

When I enter this it doesn't recognize the AbstractAction method as a constructor (compiler asks for return type). Does anyone have an idea?

推荐答案

只需在扩展类名称后插入参数：

Just insert the parameters after the name of the extended class:

JButton b = new JButton(new AbstractAction("This is a button") {

    public void actionPerformed(ActionEvent e) {
        System.out.println("button clicked");
    }
}); 

此外，您可以使用初始化块：

Also, you can use an initialization block:

JButton b = new JButton(new AbstractAction() {

    {
       // Write initialization code here (as if it is inside a no-arg constructor)
       setLabel("This is a button")
    }

    public void actionPerformed(ActionEvent e) {
        System.out.println("button clicked");
    }
}); 

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