问答题

下面程序的目的是在屏幕上显示当前目录下的文件信息。文件信息通过表格JTable的实例显示。请改正程序中的错误(有下划线的语句)，使程序能输出正确的结果。
注意：不改动程序的结构，不得增行或删行。
import java.awt.*;
import javax.swing.*;
import java.util. Date;
import javax.swing.table.*;
import java.applet.*;
import java.io.*;
public class Example3_10 extends JApplet, JFrame
public void init()

FileModel fm = new FileModel();
JTable jt = new JTable();
jt.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
jt.setColumnSelectionAllowed(true);
JScrollPane jsp = new JScrollPane(jt);
getContentPane().add(jsp, BorderLayout.CENTER);


public static void main(String args[])

Example3_10 ft = new Example3_10();
ft.init();
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT ON CLOSE);
f.getContentPane() .add(ft.getContentPane());
f.setSize (300, 400);
f.show();

class FileModel extends AbstractTableModel
String[] columnName = new String[]
"文件名", "大小", "最后修改时间"

Object[] [] data;
public FileModel() this(".");
public FileModel(String dir)

File file = new File(dir);
String files[] = file.list();
data = new Object [files.length] [columnName.length];
for (int i=0; i ＜ files.length; i++)

File tmp = new File (files[i]);
data[i] [0] = tmp.getName();
data[i] [1] = new Long(tmp.length());
data[i] [2] = new Date(tmp.lastModified() );

public int getColumnNumber()
return columnName.length;
public int getRowCount()
return data. length;
public String getColumnName(int col)
return columnName[col];
public Object getValueAt(int row, int col)
return data[row] [col];
public Class getColumnClass(int c)
return getValueAt (0, c) .getClass();