如何将 MouseListener 添加到框架

How To Add A MouseListener To A Frame(如何将 MouseListener 添加到框架)

问题描述

I want to add a mouselistener to mt JFrame frame but when i do frame.addMouseListener(this) i get an error that i cannot use this in a static method

I am making an application that detects a click of the mouse then displays it in int clicks

code

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JTextField;

public class numberOfClicks implements MouseListener{

    static int clicks = 0;

    @Override
    public void mouseClicked(MouseEvent e) {
        clicks++;
    }

    static JTextField text = new JTextField();
    static String string = clicks+" Clicks";

    static JFrame frame = new JFrame("Click Counter");
    public static void frame(){
        Font f = new Font("Engravers MT", Font.BOLD, 23);
        text.setEditable(false);
        text.setBackground(Color.BLUE);
        text.setFont(f);
        text.setForeground(Color.GREEN);
        text.setBorder(BorderFactory.createLineBorder(Color.BLUE));
        text.setText(string);

        frame.add(text, BorderLayout.SOUTH);
        frame.setResizable(false);
        frame.setSize(300, 300);
        frame.getContentPane().setBackground(Color.BLUE);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
        frame.addMouseListener(this);
    }

    public static void main(String[] args){
        frame();
    }

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

this doesn't exist in a static method since a static method is a method of the class, not of the object (the owner of this). Solution: get rid of all statics from your code above. None of your fields or methods above should be static other than the main method.

Edit
And as Andrew Thompson correctly states, add the MouseListener to a JPanel that is added to the JFrame's contentPane.

Edit 2

• You will want to learn and use Java naming conventions. Class names (i.e., NumberOfClicks) should start with an upper case letter. Method and variable names with a lower-case letter.
• You are better off using the mousePressed(...) method rather than the mouseClicked(...) since the former is less persnickety about accepting presses.
• You will also want to set your JTextField's text in your mousePressed(...) method since just changing the clicks value isn't enough to change the display.
• I try to avoid having my GUI (or "view") classes implement my listeners. I prefer to use anonymous inner classes or stand-alone classes where possible.

e.g.,

  JPanel mainPanel = new JPanel();
  mainPanel.addMouseListener(new MouseAdapter() {
     @Override
     public void mousePressed(MouseEvent e) {
        clicks++;
        text.setText(clicks + " Clicks");
     }
  });
  // add mainPanel to the JFrame...

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