Question

我正在尝试在用户点击JFrame的位置绘制类似月亮的形状（或者可能是使用我的代码实现的任何任意形状）。但我得到运行时异常：

Exception in thread "AWT-EventQueue-0" java.lang.StackOverflowError
at java.awt.geom.AffineTransform.<init>(AffineTransform.java:488)
at sun.java2d.SunGraphics2D.clone(SunGraphics2D.java:267)
at sun.java2d.SunGraphics2D.create(SunGraphics2D.java:300)
at javax.swing.JComponent.paint(JComponent.java:1000)
at Shapes$component.paintComponent(Shapes.java:48)
at javax.swing.JComponent.paint(JComponent.java:1054)
at Shapes$component.paintComponent(Shapes.java:48)
at javax.swing.JComponent.paint(JComponent.java:1054)
at Shapes$component.paintComponent(Shapes.java:48)
at javax.swing.JComponent.paint(JComponent.java:1054)
at Shapes$component.paintComponent(Shapes.java:48)
at javax.swing.JComponent.paint(JComponent.java:1054)
at Shapes$component.paintComponent(Shapes.java:48)
at javax.swing.JComponent.paint(JComponent.java:1054)
at Shapes$component.paintComponent(Shapes.java:48)
at javax.swing.JComponent.paint(JComponent.java:1054)

我错在哪里？如何删除此错误。

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Area;
import java.awt.geom.Ellipse2D;
import java.util.ArrayList;

import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;


public class Shapes extends JFrame{
private ArrayList shapes=new ArrayList();
    Shapes()
{
super("Creating moon on mouse clicks");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(400,400);

addMouseListener(new listener());
add(new component());
setVisible(true);
}
public class listener extends MouseAdapter
{
public void mouseClicked(MouseEvent e)
{
    int x=e.getX();
    int y=e.getY();
    int rand=(int) Math.floor(Math.random()*x);
    int temp;
    Area a1=new Area(new Ellipse2D.Double(x,y,rand,rand));
    temp=(int)rand/3;
    Area a2=new Area(new Ellipse2D.Double(x+temp,y+temp,temp,temp));
    a1.subtract(a2);
    shapes.add(a1);
    repaint();
}
}
public class component extends JComponent
{
public void paintComponent(Graphics g)
{
    super.paint(g);
    Graphics2D g2=(Graphics2D)g.create();
    for(int i=0;i<shapes.size();i++)
    {
        g2.draw((Shape) shapes.get(i));
    }
}
}
public static void main(String[] args) {
// TODO Auto-generated method stub
    SwingUtilities.invokeLater(new Runnable(){public void run(){new Shapes();}});
}

}

Answer 1

当您覆盖paintComponent()时，您正在呼叫super.paint()而不是super.paintComponent()。

JComponent.paint()的默认实施会执行paintComponent()，paintBorder()和paintChildren()。因此，从super.paint()执行paintComponent()会创建无限的执行循环。这就是StackOverflowError的原因。

Answer 2

这是错误的......

public void paintComponent(Graphics g)
{
    super.paint(g);
    // ...
}

万一你错过了它;） - 应该阅读

public void paintComponent(Graphics g)
{
    super.paintComponent(g);
    // ...
}

需要帮助来运行我的swing图形代码

2 个答案: