NewTest延伸JPanel; 但由于你并未在对的每次调用中绘制每个像素paintComponent()，因此你需要调用超类的方法并清除旧的绘制：
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int width = this.getWidth();
int height = this.getHeight();
g.setColor(Color.black);
g.fillRect(0, 0, width, height);
...
}
附录：如你所述，在构造函数中设置背景色无需在中填充面板paintComponent()，而super.paintComponent()允许文本字段正常运行。如你所见，建议的解决方法很脆弱。相反，请简化代码并按要求进行优化。例如，你可能不需要插入，复杂的缓冲区和组件侦听器的复杂性。
附录2：请注意，super.paintComponent()调用UI委托的update()方法，“该方法将用其背景颜色填充指定的组件（如果其opaque属性为true）”。你可以使用它setOpaque(false)来避免这种情况。
动画测试
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsEnvironment;
import java.awt.Rectangle;
import java.awt.Transparency;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.Timer;
/** @see http://stackoverflow.com/questions/3256941 */
public class AnimationTest extends JPanel implements ActionListener {
private static final int WIDE = 640;
private static final int HIGH = 480;
private static final int RADIUS = 25;
private static final int FRAMES = 24;
private final Timer timer = new Timer(20, this);
private final Rectangle rect = new Rectangle();
private BufferedImage background;
private int index;
private long totalTime;
private long averageTime;
private int frameCount;
public static void main(String[] args) {
EventQueue.invokelater(new Runnable() {
@Override
public void run() {
new Animationtest().create();
}
});
}
private void create() {
JFrame f = new JFrame("AnimationTest");
f.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
timer.start();
}
public Animationtest() {
super(true);
this.setOpaque(false);
this.setPreferredSize(new Dimension(WIDE, HIGH));
this.addMouseListener(new MouseHandler());
this.addComponentListener(new ComponentHandler());
}
@Override
protected void paintComponent(Graphics g) {
long start = System.nanoTime();
super.paintComponent(g);
int w = this.getWidth();
int h = this.getHeight();
g.drawImage(background, 0, 0, this);
double theta = 2 * Math.PI * index++ / 64;
g.setColor(Color.blue);
rect.setRect(
(int) (Math.sin(theta) * w / 3 + w / 2 - RADIUS),
(int) (Math.cos(theta) * h / 3 + h / 2 - RADIUS),
2 * RADIUS, 2 * RADIUS);
g.fillOval(rect.x, rect.y, rect.width, rect.height);
g.setColor(Color.white);
if (frameCount == FRAMES) {
averageTime = totalTime / FRAMES;
totalTime = 0; frameCount = 0;
} else {
totalTime += System.nanoTime() - start;
frameCount++;
}
String s = String.format("%1$5.3f", averageTime / 1000000d);
g.drawString(s, 5, 16);
}
@Override
public void actionPerformed(ActionEvent e) {
this.repaint();
}
private class MouseHandler extends MouseAdapter {
@Override
public void mousePressed(MouseEvent e) {
super.mousePressed(e);
JTextField field = new JTextField("test");
Dimension d = field.getPreferredSize();
field.setBounds(e.getX(), e.getY(), d.width, d.height);
add(field);
}
}
private class ComponentHandler extends ComponentAdapter {
private final GraphicsEnvironment ge =
GraphicsEnvironment.getLocalGraphicsEnvironment();
private final GraphicsConfiguration gc =
ge.getDefaultScreenDevice().getDefaultConfiguration();
private final Random r = new Random();
@Override
public void componentResized(ComponentEvent e) {
super.componentResized(e);
int w = getWidth();
int h = getHeight();
background = gc.createCompatibleImage(w, h, Transparency.OPAQUE);
Graphics2D g = background.createGraphics();
g.clearRect(0, 0, w, h);
g.setColor(Color.green.darker());
for (int i = 0; i < 128; i++) {
g.drawLine(w / 2, h / 2, r.nextInt(w), r.nextInt(h));
}
g.dispose();
System.out.println("Resized to " + w + " x " + h);
}
}
}
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