Question

我打算制作一个非常简单的游戏，其中一个正方形沿着二维楼层移动。要做到这一点，我需要添加2个形状，但由于某种原因，它们不会出现在屏幕上。我认为绘制实际形状的代码存在问题，因为当我省略添加第二个形状的部分时，它仍然无法正常工作。如果有人可以指出我的代码中的错误，以便我可以修复它们（我一分钟不关心keylistener代码）那么这将非常有用。

主类：

import java.awt.*;
import javax.swing.*;
public class mainClass3 {
public static void main(String[] args) {
        // TODO Auto-generated method stub
    JFrame window = new JFrame();
    window.setSize(600,400);
    window.setVisible(true);
    window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    window.getContentPane().setBackground(Color.white);
    window.setLayout(null);
    Graphics3 DC = new Graphics3();
    window.addKeyListener(DC);
    window.add(DC);
    Floor2 floor = new Floor2();
    window.add(floor);

        }

    }

图形类（方块）：

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class Graphics3 extends JComponent implements KeyListener{
    int x = 5;
    int y = 200;
    public void paintComponent(Graphics g) {
        Rectangle rect = new Rectangle(x,y,100,100);
        Graphics2D g2 =(Graphics2D)g;
        rect.setLocation(x,y);
        g2.setColor(Color.CYAN);
        g2.fill(rect);      
    }
    @Override
    public void keyPressed(KeyEvent e) {
        if(e.getKeyCode() == KeyEvent.VK_LEFT) {
            x-=1;
    }


    // TODO Auto-generated method stub

    }
    @Override
    public void keyReleased(KeyEvent arg0) {
    // TODO Auto-generated method stub

    }
    @Override
    public void keyTyped(KeyEvent arg0) {
    // TODO Auto-generated method stub

    }

 }

其他图形类（发言权）：

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.*;
import javax.swing.*;
public class Floor2 extends JComponent{
    public void paintComponent2(Graphics g) {
        Graphics2D g2 = (Graphics2D)g;
        Rectangle floor1 = new Rectangle (0,300,600,100);
        floor1.setLocation(permanentx,permanenty);
        g2.setColor(Color.black);
        g2.fill(floor1);        
        }
    }

Answer 1

window.setLayout(null);是您的问题之一。布局管理API执行一些非常重要的工作，根据布局实现自动定位和调整组件，您刚刚离开并丢弃。

请查看Laying Out Components Within a Container了解详情。

另一个是试图以这种方式使用组件。

我建议稍微改变一下。而不是使用两个不同的组件，创建一个单独的组件，作为游戏表面＆＃34;。这是所有相关绘画完成的地方，地板和矩形。这提供了一个更好的自包含环境，更容易控制和维护。

在＆＃34之前发布您的下一个问题之前，为什么我的KeyListener无法正常工作＆＃34; - 请查看How to use Key Bindings将解决的问题与KeyListener

相关的焦点问题

Answer 2

我在这里和那里改变了你的代码，但它终于有效了。我决定使用null布局，因为在这种情况下它是合适的。无论如何，这是我的代码：

import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Rectangle;

import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.WindowConstants;

public class mainClass3 {

    public static void main(final String[] arguments) {
        JFrame frame = new JFrame();
        // Never forget to manipulate swing objects under the event dispatch queue.
        EventQueue.invokeLater(() -> {
            frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
            frame.setSize(600, 400);
            // I'll use the null layout. Don't blame me.
            frame.setLayout(null);
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
            // Specifies the position, as well as the width and height of the square.
            final Rectangle rectangle01 = new Rectangle(5, 200, 100, 100);
            // Determines the position and size of the floor.
            final Rectangle rectangle02 = new Rectangle(0, 300, 600, 100);
            // Now, here is the first big difference between your and my code: composition over inheritance.
            @SuppressWarnings("serial")
            final JPanel square = new JPanel() {
                @Override
                public void paintComponent(final Graphics graphics) {
                    super.paintComponent(graphics);
                    graphics.setColor(Color.RED);
                    graphics.fillRect(0, 0, rectangle01.width, rectangle01.height);
                    graphics.drawRect(0, 0, rectangle01.width, rectangle01.height);
                }
            };
            // Let's also add a working key listener, shall we?
            frame.addKeyListener(new KeyAdapter() {
                @Override
                public void keyPressed(final KeyEvent event) {
                    super.keyPressed(event);
                    switch (event.getKeyCode()) {
                    case KeyEvent.VK_D:
                        square.setLocation(square.getX() + 6, square.getY());
                        break;
                    case KeyEvent.VK_A:
                        square.setLocation(square.getX() - 6, square.getY());
                        break;
                    }
                }
            });
            // Don't forget to set the bounds of a component when working with a null layout!
            square.setBounds(rectangle01);
            @SuppressWarnings("serial")
            final JPanel floor = new JPanel() {
                @Override
                public void paintComponent(final Graphics graphics) {
                    super.paintComponent(graphics);
                    graphics.setColor(Color.BLACK);
                    graphics.fillRect(0, 0, rectangle02.width, rectangle02.height);
                    graphics.drawRect(0, 0, rectangle02.width, rectangle02.height);
                }
            };
            // And don't forget to set the bounds here too.
            floor.setBounds(rectangle02);
            // Now, just add all components to the frame. Voilà!
            frame.add(square);
            frame.add(floor);
        });
    }    
}

只是想感谢你顺便回答我的一个问题。

无法在java中为JFrame添加2个形状

2 个答案: