java - java.awt.event.MouseListener 中的错误 : WindowText is not abstract and does not override abstract method mouseExited(java. awt.event.MouseEvent)

Question

我编写了一个程序来显示一个带有标签、文本字段和按钮的窗口。当鼠标单击文本字段时，应调用程序 VirtualKeyboardTest.java。

import java.awt.*;
import java.awt.event.*;

class WindowText implements MouseListener
{
    public static void main(String[] args) 
    {
        Frame f=new Frame("New Window");
        f.setSize(500,300);
        f.setVisible(true);
        f.addWindowListener(new WindowAdapter(){
            public void windowClosing(WindowEvent e){
                System.exit(0);
            }
        });
        Panel p = new Panel();
        Panel p1 = new Panel();
        Label lb = new Label("Click on textfield");
        TextField tf = new TextField(20);
        tf.addMouseListener(new MouseAdapter(){
            public void mouseClicked(MouseEvent e)
            {
                new VirtualKeyboardTest();
            }
            public void mousePressed(MouseEvent e){}
            public void mouseEntered(MouseEvent e){}
            public void mouseExited(MouseEvent e){}
            public void mouseReleased(MouseEvent e){}
        });

        p.setLayout(new FlowLayout());
        p.add(lb);
        p.add(tf);

        Button Submit=new Button("Submit");
        p.add(Submit);
        p1.add(p);
        f.add(p1,BorderLayout.CENTER);
    }
}

但是当我尝试编译这个程序时，我收到一个错误

 WindowText.java:4: WindowText is not abstract and does not override abstract method mouseExited(java.awt.event.MouseEvent) in java.awt.event.MouseListener
    class WindowText implements MouseListener
    ^
    1 error

我不明白为什么我会收到此错误，即使我已经覆盖了 MouseListener 中的每个方法。

Answer 1

您需要实现 MouseListener 具有的方法。

                public void mousePressed(MouseEvent e){}
                public void mouseEntered(MouseEvent e){}
                public void mouseExited(MouseEvent e){}
                public void mouseReleased(MouseEvent e){}

必须在 MouseText 中被覆盖。但由于您有一个匿名适配器，因此 MouseText 实现 MouseListener 似乎是多余的。