椭圆形移动程序。椭圆不动，有啥我可以在这里炼制的吗？
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【中文标题】椭圆形移动程序。椭圆不动，有啥我可以在这里炼制的吗？【英文标题】：Oval moving program. Oval not moving, anything I can refine here?椭圆形移动程序。椭圆不动，有什么我可以在这里炼制的吗？ 【发布时间】：2019-05-12 22:34:44 【问题描述】：我在这里需要一些关于我的代码的帮助。我完成了创建键盘事件的过程，如果我按下箭头键向下移动我的椭圆，如果我按下箭头键向上移动等等。但是，我一直无法这样做。有什么我可以从我的代码中改进的吗？还计划在两个按钮中实现它，右翻译和左翻译按钮。
提前感谢您！ Here is the example UI that I've made so far.
import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
public class page309_4 extends JFrame //implements ActionListener
private JButton btnLeftMvmt, btnRightMvmt;
int oval_x = 150;
int oval_y = 150;
public page309_4()
setTitle("Oval Mover");
setSize(600, 150);
setLayout(new BorderLayout());
JPanel panel1, panel2;
panel1 = new JPanel();
panel2 = new JPanel();
panel1.setSize(500,300);
panel1.add(new MyPanel());
panel1.addKeyListener(new KeyAdapter()
public void keyPressed(KeyEvent e)
int keycode = e.getKeyCode();
switch (keycode)
case KeyEvent.VK_UP: oval_y += 10; break;
case KeyEvent.VK_DOWN: oval_y -= 10; break;
case KeyEvent.VK_LEFT: oval_x -= 10; break;
case KeyEvent.VK_RIGHT: oval_x += 10; break;
);
panel1.setBackground(Color.YELLOW);
btnLeftMvmt = new JButton("Left Translation");
btnRightMvmt = new JButton("Right Translation");
btnLeftMvmt.addActionListener(bleft ->
);
btnRightMvmt.addActionListener(bright ->
);
panel2.add(btnLeftMvmt);
panel2.add(btnRightMvmt);
add(panel1);
add(panel2, BorderLayout.SOUTH);
pack();
setLocationRelativeTo(null);
setVisible(true);
class MyPanel extends JPanel
public MyPanel()
setPreferredSize(new Dimension(600, 150));
@Override
public void paintComponent(Graphics g)
super.paintComponents(g);
g.setColor(Color.RED);
int oval_x = (getWidth() - 150) / 2;
int oval_y = (getHeight() - 150) / 2;
g.fillOval(oval_x, oval_y, 150, 150);
public static void main (String[] args)
// TODO Auto-generated method stub
page309_4 f = new page309_4();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
【问题讨论】：
不要硬编码你的椭圆位置 椭圆的坐标应该由MyPanel 类维护。在KeyListener上使用key bindings api，它将解决焦点相关问题
【参考方案1】：
您不会在按键后重新绘制 panel1，因此您永远不会看到更改。要解决此问题，请在 keyPressed() 处理程序的末尾添加 panel1.repaint()。
【讨论】：
不会有所作为 这是问题的一部分，但需要进行更多更改才能使某些东西在这里起作用。【参考方案2】：让我们从……开始吧
@Override
public void paintComponent(Graphics g)
super.paintComponents(g);
g.setColor(Color.RED);
int oval_x = (getWidth() - 150) / 2;
int oval_y = (getHeight() - 150) / 2;
g.fillOval(oval_x, oval_y, 150, 150);
x/y 位置在方法中定义，因此无论您做什么，它都不会改变。
话虽如此，MyPanel 应该直接负责管理 x/y 位置，这意味着应该在其中定义 oval_x 和 oval_y 变量。然后，您应该定义可以更改这些值的功能，例如...
class MyPanel extends JPanel
private int oval_x = 150;
private int oval_y = 150;
public MyPanel()
@Override
public Dimension getPreferredSize()
return new Dimension(600, 150);
public void moveVerticallyBy(int delta)
oval_y += delta;
repaint();
public void moveHorizontallyBy(int delta)
oval_x += delta;
repaint();
@Override
protected void paintComponent(Graphics g)
super.paintComponents(g);
g.setColor(Color.RED);
g.fillOval(oval_x, oval_y, 150, 150);
这是封装的基本概念
接下来，我强烈建议使用key bindings API 而不是KeyListener，因为它可以解决焦点相关的问题。
例如...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
public class Page309_4 extends JFrame //implements ActionListener
private JButton btnLeftMvmt, btnRightMvmt;
private MyPanel myPanel;
public Page309_4()
setTitle("Oval Mover");
setSize(600, 150);
setLayout(new BorderLayout());
JPanel panel1, panel2;
panel2 = new JPanel();
myPanel = new MyPanel();
InputMap im = myPanel.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
ActionMap am = myPanel.getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "Pressed.up");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), "Pressed.down");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), "Pressed.left");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), "Pressed.right");
am.put("Pressed.up", new VerticalMovementAction(-10, myPanel));
am.put("Pressed.down", new VerticalMovementAction(10, myPanel));
am.put("Pressed.left", new HorizontalMovementAction(-10, myPanel));
am.put("Pressed.right", new HorizontalMovementAction(10, myPanel));
btnLeftMvmt = new JButton("Left Translation");
btnRightMvmt = new JButton("Right Translation");
btnLeftMvmt.addActionListener(bleft ->
);
btnRightMvmt.addActionListener(bright ->
);
panel2.add(btnLeftMvmt);
panel2.add(btnRightMvmt);
add(myPanel);
add(panel2, BorderLayout.SOUTH);
pack();
setLocationRelativeTo(null);
setVisible(true);
public class VerticalMovementAction extends AbstractAction
private int delta;
private MyPanel myPanel;
public VerticalMovementAction(int delta, MyPanel myPanel)
this.delta = delta;
this.myPanel = myPanel;
@Override
public void actionPerformed(ActionEvent e)
myPanel.moveVerticallyBy(delta);
public class HorizontalMovementAction extends AbstractAction
private int delta;
private MyPanel myPanel;
public HorizontalMovementAction(int delta, MyPanel myPanel)
this.delta = delta;
this.myPanel = myPanel;
@Override
public void actionPerformed(ActionEvent e)
myPanel.moveHorizontallyBy(delta);
class MyPanel extends JPanel
private int oval_x = (600 - 150) / 2;
private int oval_y = (300 - 150) / 2;
public MyPanel()
setBackground(Color.YELLOW);
@Override
public Dimension getPreferredSize()
return new Dimension(600, 300);
public void moveVerticallyBy(int delta)
oval_y += delta;
repaint();
public void moveHorizontallyBy(int delta)
oval_x += delta;
repaint();
@Override
protected void paintComponent(Graphics g)
super.paintComponents(g);
g.setColor(Color.RED);
g.fillOval(oval_x, oval_y, 150, 150);
public static void main(String[] args)
EventQueue.invokeLater(new Runnable()
@Override
public void run()
// TODO Auto-generated method stub
Page309_4 f = new Page309_4();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
);
【讨论】：
非常感谢！我从来不知道键绑定 API，因为我的校园没有教授它。再次感谢您，对您有很大帮助！以上是关于椭圆形移动程序。椭圆不动，有啥我可以在这里炼制的吗？的主要内容，如果未能解决你的问题，请参考以下文章