如何使用对象序列化java从文件加载线数组对象

该程序旨在使用户能够用线条绘制某些内容，并将其保存到可加载的文件中，使用ObjectOutput writeObject方法保存效果很好，但加载的文件不起作用，如果保存文件，则可以再绘制一条线条，以使显示与保存的内容不同，但使用ObjectInputStream readObject方法加载时，它不会在面板上显示保存的图形

import java.awt.*;
import java.awt.event.*;
import javax.swing.JPanel;
import javax.swing.JLabel;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JOptionPane;
import java.io.*;

public class DrawLine extends JPanel
{
  private LineClass lines[];
  private String fileName;
  private int lineCount;
  private LineClass currentLine;
  public JLabel statusLabel;
  private int currShapeX1,currShapeY1;
  private static JButton saveButton, loadButton;
  private ObjectOutputStream output;
  private ObjectInputStream input;
  private JFileChooser fileChooser;
  public DrawLine()
  {
    statusLabel = new JLabel("(0,0)");
    saveButton = new JButton("Save");
    loadButton = new JButton("Load");
    lines = new LineClass[100];
    lineCount = 0;
    currentLine = null;

    MouseHandler handler = new MouseHandler();
    addMouseListener(handler);
    addMouseMotionListener(handler);
    saveButton.addActionListener(handler);
        loadButton.addActionListener(handler);



      }


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

    for(int count = 0; count < lineCount; ++count)
    {
      lines[count].draw(g);
    } 
    if( currentLine != null ) {
  currentLine.draw(g); 
}
  }

  public static void main(String args[])
  {
JFrame frame = new JFrame();
DrawLine panel = new DrawLine();

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(saveButton,BorderLayout.NORTH);
frame.add(loadButton,BorderLayout.SOUTH);
frame.add(panel,BorderLayout.CENTER);
frame.setSize(400,400);
frame.setVisible(true);
  }

  private class MouseHandler extends MouseAdapter implements         MouseMotionListener, ActionListener
  {
    public void actionPerformed(ActionEvent event)
    {
      if (event.getSource() == loadButton)
      {
          fileChooser = new JFileChooser();
        fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);

        int result = fileChooser.showOpenDialog(DrawLine.this);

    if (result == JFileChooser.CANCEL_OPTION)
      System.err.println("No file selected.");
    else
    {
      File file = fileChooser.getSelectedFile();
      if ((file != null) && !(file.getName().equals("")))
      {
        fileName = file.getName();

try
{
input = new ObjectInputStream(new FileInputStream(fileName));

lines = ((LineClass[])input.readObject());
     lineCount = 0;
    for(int j = 0; j < 100; ++j)
    {
      if (lines[j] == null)
        break;
      else
        lineCount++;
    }
repaint();        
}
catch(EOFException ex)
{
  System.out.println("Finished loading file");
}
catch(IOException ex)
{
  JOptionPane.showMessageDialog(DrawLine.this, "Error loading \""+fileName+"\"", "Error Message", JOptionPane.ERROR_MESSAGE);
}
catch(ClassNotFoundException ex)
{
  JOptionPane.showMessageDialog(DrawLine.this, "Unable to create object", "Error Message", JOptionPane.ERROR_MESSAGE);
}
      }
  }
  }
  if (event.getSource() == saveButton)
  {
    fileChooser = new JFileChooser();
    fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);

    int result = fileChooser.showSaveDialog(DrawLine.this);

    if (result == JFileChooser.CANCEL_OPTION)
      System.err.println("File was not saved");
    else if (result == JFileChooser.APPROVE_OPTION)
    {
      File file = fileChooser.getSelectedFile();

      if ((file != null)&&!(file.getName().equals("")))
      {
        fileName = file.getName()+".drw";


     try
{
  output = new ObjectOutputStream(new FileOutputStream(fileName));
    output.writeObject(lines);
  output.close();
  System.out.println(fileName+" saved");
}
catch(IOException ex)
{
  JOptionPane.showMessageDialog(DrawLine.this, "Error saving \""+fileName+"\"", "Error Message", JOptionPane.ERROR_MESSAGE);
}
  }
    }
  }
}
public void mousePressed(MouseEvent event)
{
  //it assigns currentShape a new shape and initializes both points to the mouse position.
  currShapeX1 = event.getX();
  currShapeY1 = event.getY();           
}
public void mouseReleased(MouseEvent event)
{
  //finish drawing the current shape and place it in the array
  //Set the second point of currentShape to the current mouse position
    currentLine = new LineClass(currShapeX1,currShapeY1,event.getX(),event.getY());

  // and add currentShape to the array.
  //Instance variable shapeCount determines the insertion index. Set currentShape to null and call method repaint to update the drawing with the new shape.
  lines[lineCount] = currentLine;
  lineCount++;

  currentLine = null;
  repaint();
}
public void mouseDragged(MouseEvent event)
{

  //it sets the second point of the currentShape to the current mouse position and calls method repaint

  //finish drawing the current shape and place it in the array
  //Set the second point of currentShape to the current mouse position
    currentLine = new LineClass(currShapeX1,currShapeY1,event.getX(),event.getY());

  // and add currentShape to the array.
  //Instance variable shapeCount determines the insertion index. Set currentShape to null and call method repaint to update the drawing with the new shape.
  //lines[lineCount] = currentLine;

  //currentLine = null;
  repaint();
  statusLabel.setText(String.format("(%d,%d)",event.getX(),event.getY()));
}

public void mouseMoved(MouseEvent event)
{
  //to set the text of the statusLabel so that it displays the mouse coordinates—this will update the label with the coordinates every time the user moves 
  //(but does not drag) the mouse within the DrawPanel
  statusLabel.setText(String.format("(%d,%d)",event.getX(),event.getY()));
}
}
}

//LineClass
class LineClass implements Serializable
{
private int x1;
private int y1;
private int x2;
private int y2;

public LineClass(int x1, int y1, int x2, int y2)
{
this.x1 = x1;
this.y1 = y1;
this.x2 = x2;
this.y2 = y2;
}

public void draw(Graphics g)
{
g.drawLine(x1,y1,x2,y2);
}
}

import java.awt.*；
导入java.awt.event.*；
导入javax.swing.JPanel；
导入javax.swing.JLabel；
导入javax.swing.JFrame；
导入javax.swing.JButton；
导入javax.swing.JFileChooser；
导入javax.swing.JOptionPane；
导入java.io.*；
公共类抽绳延伸至JPanel
{
专用LineClass线路[]；
私有字符串文件名；
私有整数行计数；
私有线路类currentLine；
公共JLabel状态标签；
专用int currShapeX1，currShapeY1；
私有静态JButton saveButton、loadButton；
私有对象输出流输出；
私有对象输入流输入；
私有JFileChooser文件选择器；
公共抽绳（）
{
statusLabel=新的JLabel（“（0,0）”）；
saveButton=新的JButton（“Save”）；
loadButton=新的JButton（“加载”）；
线条=新线条类别[100]；
行数=0；
currentLine=null；
MouseHandler handler=新的MouseHandler（）；
addMouseListener（handler）；
addMouseMotionListener（处理程序）；
saveButton.addActionListener（处理程序）；
loadButton.addActionListener（处理程序）；
}
公共组件（图形g）
{
超级组件（g）；
对于（int count=0；countfor (int loop = 0; loop < lines.length; loop++)
{
  if (lines[loop] == null)
  {
    lineCount = loop;
    break;
  }
}

lineCount = lines.length;