这样调用怎么不行啊？
下面有个地方调用怎么不行啊70行的 p.paintLine(ul);
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
import java.io.*;
public class ScribbleDemo extends JFrame implements ActionListener{

JMenuBar menubar=new JMenuBar();
JMenu [] menus= new JMenu[]
{
new JMenu( "文件 "),
new JMenu( "编辑 "),
new JMenu( "查找 "),
new JMenu( "帮助 ")
};
JMenuItem menuitems [][] =new JMenuItem[][]
{
{
new JMenuItem( "打开 "),
new JMenuItem( "保存 "),
new JMenuItem( "退出 ")
},
{
new JMenuItem( "全选 "),
new JMenuItem( "剪切 "),
new JMenuItem( "粘贴 "),
new JMenuItem( "复制 ")
},
{
new JMenuItem( "查找 "),
new JMenuItem( "替换 ")
},
{
new JMenuItem( "About ")
}
};
private FileDialog fd;
private LinkedList[] m=new LinkedList[20];
public ScribblePanel p =new ScribblePanel();
public ScribbleDemo() {
// Create a PaintPanel and add it to the content pane
getContentPane().add(p, BorderLayout.CENTER);
for(int i=0;i <menus.length;i++)
{
menubar.add(menus[i]);
for(int j=0;j <menuitems[i].length;j++)
{

menus[i].add(menuitems[i][j]);
menuitems[i][j].addActionListener(this);
}
}
this.setJMenuBar(menubar);
}
public void actionPerformed(ActionEvent e)
{
String choose =e.getActionCommand();
//if(choose.equals( "保存 "))
//this.openFile();

}
public void openFile()
{
fd=new FileDialog(this, "打开 ",FileDialog.LOAD);
fd.setVisible(true);
String path=fd.getDirectory()+ "// "+fd.getFile();
try
{
FileInputStream fin = new FileInputStream(path);
ObjectInputStream in = new ObjectInputStream(fin);
LinkedList[] u1 = (LinkedList[])in.readObject(); //读取对象
p.paintLine(ul);//********这个地方怎么不行啊？？
}
catch (FileNotFoundException fe){}
catch (IOException ioe){}
catch (ClassNotFoundException ioe) {}


}

/** Main method */
public static void main(String[] args) {
ScribbleDemo frame = new ScribbleDemo();
frame.setTitle( "ScribbleDemo ");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(300, 300);
frame.setVisible(true);
}
}

// ScribblePanel for scribbling using the mouse
class ScribblePanel extends JPanel
implements MouseListener, MouseMotionListener {
final int CIRCLESIZE = 20; // Circle diameter used for erasing
private Point lineStart = new Point(0, 0); // Line start point

//private LinkedList l=new LinkedList();
private LinkedList[] m=new LinkedList[20];//最多20条线
private int i=0;
protected void paintComponent(Graphics g)

{
super.paintComponent(g);
paintLine(m);
}

public void paintLine(LinkedList[] m)
{
Graphics g=this.getGraphics();
Point start=new Point(0, 0);
Point end=new Point(0, 0);
for(int k=0;k <i;k++)
{
if(m[k].size()> 0)
{
start.move(((Point)m[k].get(0)).x,((Point)m[k].get(0)).y);
for(int n=1;n <m[k].size();n++)
{
end.move(((Point)m[k].get(n)).x,((Point)m[k].get(n)).y);
g.drawLine(start.x,start.y,end.x,end.y);
start.move(((Point)m[k].get(n)).x,((Point)m[k].get(n)).y);
}
}
}
}
public ScribblePanel() {
// Register listener for the mouse event
addMouseListener(this);
addMouseMotionListener(this);
}

public void mouseClicked(MouseEvent e) {
}

public void mouseEntered(MouseEvent e) {
}

public void mouseExited(MouseEvent e) {
}

public void mouseReleased(MouseEvent e) {
}

public void mousePressed(MouseEvent e) {
lineStart.move(e.getX(), e.getY());
LinkedList l=new LinkedList();
m[i]=l;
Point s=new Point(e.getX(),e.getY());
l.add(s);
i++;

}

public void mouseDragged(MouseEvent e) {
// Create a Graphics object for drawing
Graphics g = getGraphics();
Point s=new Point(e.getX(),e.getY());
if (e.isMetaDown()) { // Detect right button pressed
// Erase the drawing using an oval
g.setColor(getBackground());
g.fillOval(e.getX() - (CIRCLESIZE / 2),
e.getY() - (CIRCLESIZE / 2), CIRCLESIZE, CIRCLESIZE);
}
else {
g.setColor(Color.black);
g.drawLine(lineStart.x, lineStart.y,

e.getX(), e.getY());
}

lineStart.move(e.getX(), e.getY());
m[i-1].add(s);
g.dispose();
}

public void mouseMoved(MouseEvent e) {
}
}


[解决办法]
是u1，不是ul。。。
[解决办法]
LinkedList[] u1 = (LinkedList[])in.readObject(); //读取对象
p.paintLine(ul);//********这个地方怎么不行啊？？
------------------------
一个ul 一个u1 LZ啊！