java - 如何让我的 MouseListener 方法在 Java 中工作？

Question

我对java很陌生，我正在制作一个简单的像素艺术制作器。我复制了一个 for 循环来画圆圈。我用的是鼠标点击的方法。我这样做是为了当我单击时，它会打印“左”或“右”。

这是网格系统:http://www.java2s.com/Tutorials/Java/Graphics/Shape/Draw_a_grid_by_drawing_lines_in_Java.htm

这是我使用的 MouseEvent 系统:

https://github.com/DevonCrawford/A-Pathfinding-Visualization/blob/master/src/Frame.java

唯一的问题是它不打印“左”和“右”。这是我的代码:

import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

class Main extends JComponent implements MouseListener {
  public static void main(String[] args) {
    JFrame window = new JFrame();
    window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    window.setBounds(30, 30, 600, 584);
    window.getContentPane().add(new Main());
//    window.setResizable(false);
    window.setVisible(true);

  }

  public void paint(Graphics g) {
    int rows = 20;

    int cols = 20;
    int width = getSize().width;
    int height = getSize().height;

    // draw the rows
    int rowHt = height / (rows);
    for (int i = 0; i < rows; i++)
      g.drawLine(0, i * rowHt, width, i * rowHt);

    // draw the columns
    int rowWid = width / (cols);
    for (int i = 0; i < cols; i++)
      g.drawLine(i * rowWid, 0, i * rowWid, height);

  }

  public void MapCalculations(MouseEvent e) { 
    // If left mouse button is clicked
    if (SwingUtilities.isLeftMouseButton(e)) {
        System.out.println("Left");

    } 
    // If right mouse button is clicked
    else if (SwingUtilities.isRightMouseButton(e)) {
        System.out.println("Right");
    }
  }

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

  @Override
  public void mousePressed(MouseEvent e) {}

  @Override
  public void mouseReleased(MouseEvent e) {}

  @Override
  public void mouseEntered(MouseEvent e) {}

  @Override
  public void mouseExited(MouseEvent e) {}

  public void mouseDragged(MouseEvent e) {
    MapCalculations(e);
  }
}

Answer 1

鼠标监听器方法永远不会被调用，因为框架不知道何时调用它们。

尝试将鼠标监听器添加到 main 方法中的 window 对象，如下所示:

public static void main(String[] args) {
    JFrame window = new JFrame();
    Main myMain = new Main();
    window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    window.setBounds(30, 30, 600, 584);
    window.getContentPane().add(myMain);
//    window.setResizable(false);
    window.setVisible(true);    
    window.addMouseListener(myMain);
  }