Java 我们可以为WindowListener使用Lambda表达式吗？如果是，怎么做？如果没有，为什么？我可以为下面的代码段设置Lambda表达式吗？

这是我的请求，请使用lambda表达式生成代码。

lambda表达式可以替代函数接口（即具有单个非默认方法的接口）。因此，具有多种方法（

windowActivated（WindowEvent e）

，

windowClosed（WindowEvent e）

，

windowClosed（WindowEvent e）

，…）的WindowAdapter不能被lambda表达式所替代。

lambda表达式可以替代函数接口（即具有单个非默认方法的接口）. 因此，具有多种方法（

windowActivated（WindowEvent e）

，

windowClosed（WindowEvent e）

，

windowClosed（WindowEvent e）

，…）的WindowAdapter不能被lambda表达式取代。

这里不能直接使用lambda，但如果您有大量的用户界面代码，并且有大量的侦听器，您可以创建如下所示的生成器：

this.addWindowListener(new WindowAdaptor(){
public void windowClosing(WindowEvent we)
{
    System.exit(0);//to close the window
}
});

import java.awt.Window;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.util.function.Consumer;

public class ListenerBuilder {
    static final Consumer<WindowEvent> nullConsumer = e -> {}; 

    private Consumer<WindowEvent> opened = nullConsumer;
    private Consumer<WindowEvent> closing = nullConsumer;
    private Consumer<WindowEvent> closed = nullConsumer;
    private Consumer<WindowEvent> iconified = nullConsumer;
    private Consumer<WindowEvent> deiconified = nullConsumer;
    private Consumer<WindowEvent> activated = nullConsumer;
    private Consumer<WindowEvent> deactivated = nullConsumer;

    public ListenerBuilder opened(Consumer<WindowEvent> opened) 
    { this.opened = opened; return this; }

    public ListenerBuilder сlosing(Consumer<WindowEvent> closing) 
    { this.closing = closing; return this; }

    public ListenerBuilder closed(Consumer<WindowEvent> closed) 
    { this.closed = closed; return this; }

    public ListenerBuilder iconified(Consumer<WindowEvent> iconified) 
    { this.iconified = iconified; return this; }

    public ListenerBuilder deiconified(Consumer<WindowEvent> deiconified) 
    { this.deiconified = deiconified; return this; }

    public ListenerBuilder activated(Consumer<WindowEvent> activated) 
    { this.activated = activated; return this; }

    public ListenerBuilder deactivated(Consumer<WindowEvent> deactivated) 
    { this.deactivated = deactivated; return this; }

    public WindowListener build() {
        return new WindowListener() {
            public void windowOpened(WindowEvent e) {
                opened.accept(e);
            }
            public void windowIconified(WindowEvent e) {
                iconified.accept(e);
            }
            public void windowDeiconified(WindowEvent e) {
                deiconified.accept(e);
            }
            public void windowDeactivated(WindowEvent e) {
                deactivated.accept(e);
            }
            public void windowClosing(WindowEvent e) {
                closing.accept(e);
            }
            public void windowClosed(WindowEvent e) {
                closed.accept(e);
            }
            public void windowActivated(WindowEvent e) {
                activated.accept(e);
            }
        };
    }

    public void attachTo(Window w) {
        w.addWindowListener(build());
    }
}

this.addWindowListener(new ListenerBuilder()
    .opened(e -> log.info("Window is opened!"))
    .closed(e -> System.exit(0)).build());

或者像这样：

this.addWindowListener(new WindowAdaptor(){
public void windowClosing(WindowEvent we)
{
    System.exit(0);//to close the window
}
});

import java.awt.Window;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.util.function.Consumer;

public class ListenerBuilder {
    static final Consumer<WindowEvent> nullConsumer = e -> {}; 

    private Consumer<WindowEvent> opened = nullConsumer;
    private Consumer<WindowEvent> closing = nullConsumer;
    private Consumer<WindowEvent> closed = nullConsumer;
    private Consumer<WindowEvent> iconified = nullConsumer;
    private Consumer<WindowEvent> deiconified = nullConsumer;
    private Consumer<WindowEvent> activated = nullConsumer;
    private Consumer<WindowEvent> deactivated = nullConsumer;

    public ListenerBuilder opened(Consumer<WindowEvent> opened) 
    { this.opened = opened; return this; }

    public ListenerBuilder сlosing(Consumer<WindowEvent> closing) 
    { this.closing = closing; return this; }

    public ListenerBuilder closed(Consumer<WindowEvent> closed) 
    { this.closed = closed; return this; }

    public ListenerBuilder iconified(Consumer<WindowEvent> iconified) 
    { this.iconified = iconified; return this; }

    public ListenerBuilder deiconified(Consumer<WindowEvent> deiconified) 
    { this.deiconified = deiconified; return this; }

    public ListenerBuilder activated(Consumer<WindowEvent> activated) 
    { this.activated = activated; return this; }

    public ListenerBuilder deactivated(Consumer<WindowEvent> deactivated) 
    { this.deactivated = deactivated; return this; }

    public WindowListener build() {
        return new WindowListener() {
            public void windowOpened(WindowEvent e) {
                opened.accept(e);
            }
            public void windowIconified(WindowEvent e) {
                iconified.accept(e);
            }
            public void windowDeiconified(WindowEvent e) {
                deiconified.accept(e);
            }
            public void windowDeactivated(WindowEvent e) {
                deactivated.accept(e);
            }
            public void windowClosing(WindowEvent e) {
                closing.accept(e);
            }
            public void windowClosed(WindowEvent e) {
                closed.accept(e);
            }
            public void windowActivated(WindowEvent e) {
                activated.accept(e);
            }
        };
    }

    public void attachTo(Window w) {
        w.addWindowListener(build());
    }
}

this.addWindowListener(new ListenerBuilder()
    .opened(e -> log.info("Window is opened!"))
    .closed(e -> System.exit(0)).build());

---

这里不能直接使用lambdas，但如果您有大量侦听器的UI代码，则可以创建如下生成器：

this.addWindowListener(new WindowAdaptor(){
public void windowClosing(WindowEvent we)
{
    System.exit(0);//to close the window
}
});

import java.awt.Window;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.util.function.Consumer;

public class ListenerBuilder {
    static final Consumer<WindowEvent> nullConsumer = e -> {}; 

    private Consumer<WindowEvent> opened = nullConsumer;
    private Consumer<WindowEvent> closing = nullConsumer;
    private Consumer<WindowEvent> closed = nullConsumer;
    private Consumer<WindowEvent> iconified = nullConsumer;
    private Consumer<WindowEvent> deiconified = nullConsumer;
    private Consumer<WindowEvent> activated = nullConsumer;
    private Consumer<WindowEvent> deactivated = nullConsumer;

    public ListenerBuilder opened(Consumer<WindowEvent> opened) 
    { this.opened = opened; return this; }

    public ListenerBuilder сlosing(Consumer<WindowEvent> closing) 
    { this.closing = closing; return this; }

    public ListenerBuilder closed(Consumer<WindowEvent> closed) 
    { this.closed = closed; return this; }

    public ListenerBuilder iconified(Consumer<WindowEvent> iconified) 
    { this.iconified = iconified; return this; }

    public ListenerBuilder deiconified(Consumer<WindowEvent> deiconified) 
    { this.deiconified = deiconified; return this; }

    public ListenerBuilder activated(Consumer<WindowEvent> activated) 
    { this.activated = activated; return this; }

    public ListenerBuilder deactivated(Consumer<WindowEvent> deactivated) 
    { this.deactivated = deactivated; return this; }

    public WindowListener build() {
        return new WindowListener() {
            public void windowOpened(WindowEvent e) {
                opened.accept(e);
            }
            public void windowIconified(WindowEvent e) {
                iconified.accept(e);
            }
            public void windowDeiconified(WindowEvent e) {
                deiconified.accept(e);
            }
            public void windowDeactivated(WindowEvent e) {
                deactivated.accept(e);
            }
            public void windowClosing(WindowEvent e) {
                closing.accept(e);
            }
            public void windowClosed(WindowEvent e) {
                closed.accept(e);
            }
            public void windowActivated(WindowEvent e) {
                activated.accept(e);
            }
        };
    }

    public void attachTo(Window w) {
        w.addWindowListener(build());
    }
}

this.addWindowListener(new ListenerBuilder()
    .opened(e -> log.info("Window is opened!"))
    .closed(e -> System.exit(0)).build());

或者像这样：

this.addWindowListener(new WindowAdaptor(){
public void windowClosing(WindowEvent we)
{
    System.exit(0);//to close the window
}
});

import java.awt.Window;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.util.function.Consumer;

public class ListenerBuilder {
    static final Consumer<WindowEvent> nullConsumer = e -> {}; 

    private Consumer<WindowEvent> opened = nullConsumer;
    private Consumer<WindowEvent> closing = nullConsumer;
    private Consumer<WindowEvent> closed = nullConsumer;
    private Consumer<WindowEvent> iconified = nullConsumer;
    private Consumer<WindowEvent> deiconified = nullConsumer;
    private Consumer<WindowEvent> activated = nullConsumer;
    private Consumer<WindowEvent> deactivated = nullConsumer;

    public ListenerBuilder opened(Consumer<WindowEvent> opened) 
    { this.opened = opened; return this; }

    public ListenerBuilder сlosing(Consumer<WindowEvent> closing) 
    { this.closing = closing; return this; }

    public ListenerBuilder closed(Consumer<WindowEvent> closed) 
    { this.closed = closed; return this; }

    public ListenerBuilder iconified(Consumer<WindowEvent> iconified) 
    { this.iconified = iconified; return this; }

    public ListenerBuilder deiconified(Consumer<WindowEvent> deiconified) 
    { this.deiconified = deiconified; return this; }

    public ListenerBuilder activated(Consumer<WindowEvent> activated) 
    { this.activated = activated; return this; }

    public ListenerBuilder deactivated(Consumer<WindowEvent> deactivated) 
    { this.deactivated = deactivated; return this; }

    public WindowListener build() {
        return new WindowListener() {
            public void windowOpened(WindowEvent e) {
                opened.accept(e);
            }
            public void windowIconified(WindowEvent e) {
                iconified.accept(e);
            }
            public void windowDeiconified(WindowEvent e) {
                deiconified.accept(e);
            }
            public void windowDeactivated(WindowEvent e) {
                deactivated.accept(e);
            }
            public void windowClosing(WindowEvent e) {
                closing.accept(e);
            }
            public void windowClosed(WindowEvent e) {
                closed.accept(e);
            }
            public void windowActivated(WindowEvent e) {
                activated.accept(e);
            }
        };
    }

    public void attachTo(Window w) {
        w.addWindowListener(build());
    }
}

this.addWindowListener(new ListenerBuilder()
    .opened(e -> log.info("Window is opened!"))
    .closed(e -> System.exit(0)).build());

---

关于lambda和功能接口的简短参考：关于lambda和功能接口的简短参考：类似问题：类似问题：这种设计的缺点是，如果一个方法被多次调用，它会自动覆盖处理程序。此外，生成的侦听器通过构建器实例引用处理程序，这使得它是可变的，并且构建器模式的整个使用毫无意义。Lombok可以为您生成一个生成器。自动生成的生成器修复了所有提到的缺点。这种设计的缺点是，如果一个方法被多次调用，它会自动覆盖处理程序。此外，生成的侦听器通过构建器实例引用处理程序，这使得它是可变的，并且构建器模式的整个使用毫无意义。Lombok可以为您生成一个生成器。自动生成的生成器修复了所有提到的缺点。