好多看不懂...求指点...

Question

程序应该没什么问题，可就是编译的时候就出现问题了，问题：内些错误到底怎么看呢？其实我还有很多看不懂...但还是请前辈们先帮我解决这两个问题吧...谢谢大家了啊！
package mouse;

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

public class MouseFrameText {

/**
 * @param args
 */
public static void main(String[] args) {
    // TODO Auto-generated method stub
    EventQueue.invokeLater(new Runnable()
       {
           public void run()
           {
               JFrame frame=new MouseFrame();
               frame.setTitle("MouseFrame");
               frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               frame.setVisible(true);
           }
       });
}

}
class MouseFrame extends JFrame
{
public MouseFrame()
{
add(new MouseComponent());
pack();
}
}
class MouseComponent extends JComponent
{
private static final int SIDELENGTH=10;
private ArrayListsquares;
private Rectangle2D current;
public MouseComponent()
{
squares=new ArrayList<>();
current=null;

    addMouseListener(new MouseHandler());
    addMouseMotionListener(new MouseMotionHandler());
}

public void paintComponent(Graphics g)
{
Graphics2D g2=(Graphics2D) g;

for(Rectangle2D r:squares)
    g2.draw(r);

}
public Rectangle2D find(Point2D p)
{
for(Rectangle2D r:squares)
{
if(r.contains(p))
return r;
}
return null;
}
public void add(Point2D p)
{
double x=p.getX();
double y=p.getY();

current=new Rectangle2D.Double(x-SIDELENGTH/2,y-SIDELENGTH/2,SIDELENGTH,SIDELENGTH);
squares.add(current);
repaint();

}
public void remove(Rectangle2D s)
{
if(s==null) return;
if(s==current) current=null;
squares.remove(s);
repaint();
}
private class MouseHandler extends MouseAdapter
{
public void mousePressed(MouseEvent event)
{
current=find(event.getPoint());
if(current==null) add(event.getPoint());
}
public void mouseClicked(MouseEvent event)
{
current=find(event.getPoint());
if(current!=null&&event.getClickCount()>=2)
remove(current);
}
}
private class MouseMotionHandler implements MouseMotionListener
{
public void mouseMoved(MouseEvent event)
{
if(find(event.getPoint())==null)
setCursor(Cursor.getDefaultCursor());
else
setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
}
public void mouseDragged(MouseEvent event)
{
if(current!=null)
{
int x=event.getX();
int y=event.getY();
current.setFrame(x-SIDELENGTH/2,y-SIDELENGTH/2,SIDELENGTH,SIDELENGTH);
repaint();
}
}
}
}

Answer 1

你看，那个红色的字体就是控制台的输出，你完成的应该是关于图形界面的功能，你可以在这个类里某行开始执行的时候，双击左侧边，会出来一个点，这就是
断点，可以帮助你查看错误，你看它说17行，意思就是程序执行到17行就不行了，这里有错误，错误是Bad type oper....就是前几行写的那个，
你再百度这个错误，查看相关内容，最后我想说，你这个代码贴的没有高亮，我看着别扭，可能是换了markdown，所以看着不舒服，希望对你有用！！！