Java 在JPanel中未调用paintComponent
我有以下代码:Java 在JPanel中未调用paintComponent,java,jpanel,paint,Java,Jpanel,Paint,我有以下代码: package hra; import java.awt.Color; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import javax.swing.JFrame; import static javax.swing.JFrame.EXIT_ON_CLOSE; import ja
package hra;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import static javax.swing.JFrame.EXIT_ON_CLOSE;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class HerniPole extends JPanel implements KeyListener
{
public int velikostPole;
HerniPole(int velikostPole)
{
this.velikostPole = velikostPole;
Color background = new Color(187, 173, 163);
EventQueue.invokeLater(new Runnable()
{
@Override
public void run()
{
try
{
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex)
{
System.err.println("Error!");
}
}
});
JFrame frame = new JFrame();
frame.setLocationRelativeTo(null);
frame.setResizable(false);
frame.setTitle("2048");
frame.getContentPane().setBackground(background);
frame.setSize(450, 450);
frame.addKeyListener(this);
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.setVisible(true);
}
@Override
public void paintComponent(Graphics g)
{
System.out.println("xD");
g.setColor(Color.BLACK);
g.drawRect(20, 20, 20, 20);
g.setColor(Color.yellow);
}
@Override
public void keyTyped(KeyEvent ke)
{
System.out.println(ke.getKeyCode());
}
@Override
public void keyPressed(KeyEvent ke)
{
}
@Override
public void keyReleased(KeyEvent ke)
{
}
}
并且不会调用paintComponent,也不会绘制甚至重新绘制。我做错了什么?我在StackOverflow上找到的所有东西都试过了,但都没用。如何解决这个问题?谢谢。您错过了一些东西: 您没有main方法,或者可能有main方法,但没有在问题中发布,也没有创建HerniPole实例。 添加如下主方法:
public static void main(String[] args) {
new HerniPole(0);
}
您没有将HerniPole实例添加到JFrame。
在构造函数中,frame.setVisibletrue之前的某个位置执行此操作
您创建了JFrame并使其可见。但是您还没有向它添加任何组件。也许你应该创建一个HerniPole的实例并将其添加到你的JFrame中?对不起,我忘了发布我的main,frame.addthis;帮助了我。谢谢
frame.add(this);