java - 为什么我的 JFrame 无法绘制？

Question

我正在尝试使用 Graphics 绘制到我的 JFrame。由于某种原因，它不会绘制任何东西。我究竟做错了什么？我添加了我的绘画方法，导入了所有内容。我是否将该方法放置在错误的位置？

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame;

public class Main extends Canvas implements MouseListener, KeyListener {

    public int WIDTH = 1080;
    public static Main main;
    public boolean playing = false;

    public Main() {
        addMouseListener(this);
        addKeyListener(this);

        JFrame frame = new JFrame("Clicker");
        frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

    public void paint(Graphics g) {
        g.setColor(Color.BLACK);
        g.fillRect(50, 50, 100, 100);
    }

    public static void main(String[] args) {
        main = new Main();
    }

    public void MainScreen() {

    }

    @
    Override
    public void keyPressed(KeyEvent e) {
        // TODO Auto-generated method stub

    }

    @
    Override
    public void keyReleased(KeyEvent e) {
        // TODO Auto-generated method stub

    }

    @
    Override
    public void keyTyped(KeyEvent e) {
        // TODO Auto-generated method stub

    }

    @
    Override
    public void mouseClicked(MouseEvent evt) {
        // TODO Auto-generated method stub

    }

    @
    Override
    public void mouseEntered(MouseEvent evt) {
        // TODO Auto-generated method stub

    }

    @
    Override
    public void mouseExited(MouseEvent evt) {
        // TODO Auto-generated method stub

    }

    @
    Override
    public void mousePressed(MouseEvent evt) {
        // TODO Auto-generated method stub

    }

    @
    Override
    public void mouseReleased(MouseEvent evt) {
        // TODO Auto-generated method stub

    }

}

Answer 1

尝试从 JFrame 类而不是 Canvas 类扩展:

public class Main extends JFrame implements ...

您还必须编辑构造函数，例如:

public Main() {
    super("Clicker");

    addMouseListener(this);
    addKeyListener(this);

    setExtendedState(JFrame.MAXIMIZED_BOTH); 
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    setVisible(true);
}