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作业1:将指定目录下的所有文件显示到列表框(JList)组件中。
代码如下:
import java.awt.;
import java.awt.event.;
import javax.swing.;
import javax.swing.event.;
import javax.swing.border.*;
import java.util.List;
import java.util.ArrayList;
import java.io.*;
public class wj extends JFrame implements ChangeListener, ActionListener { private static final String VERSION = "Version 1.0"; private static final String WENJ_DIR = "文件"; private JList fileList; private SoundEngine player; public static void main(String[] args) { wj gui = new wj(); } public wj() { super("文件"); player = new SoundEngine(); String[] FileNames = findFiles(WENJ_DIR, null); makeFrame(FileNames); } private void quit() { System.exit(0); } private void showAbout() { JOptionPane.showMessageDialog(this, "文件\n" + VERSION, "About 文件", JOptionPane.INFORMATION_MESSAGE); } private String[] findFiles(String dirName, String suffix) { File dir = new File(dirName); if(dir.isDirectory()) { String[] allFiles = dir.list(); if(suffix == null) { return allFiles; } else { List<String> selected = new ArrayList<String>(); for(String filename : allFiles) { if(filename.endsWith(suffix)) { selected.add(filename); } } return selected.toArray(new String[selected.size()]); } } else { System.out.println("Error: " + dirName + " must be a directory"); return null; } } public void stateChanged(ChangeEvent evt) { } //添加监听器 public void actionPerformed(ActionEvent evt) { JComboBox cb = (JComboBox)evt.getSource(); String format = (String)cb.getSelectedItem(); if(format.equals("all")) { format = null; } fileList.setListData(findFiles(WENJ_DIR, format)); } private void makeFrame(String[] Files) { setDefaultCloseOperation(EXIT_ON_CLOSE); JPanel contentPane = (JPanel)getContentPane(); contentPane.setBorder(new EmptyBorder(6, 10, 10, 10)); makeMenuBar(); contentPane.setLayout(new BorderLayout(8, 8)); JPanel leftPane = new JPanel(); { leftPane.setLayout(new BorderLayout(8, 8)); String[] formats = { "all", ".doc", ".png", ".mp3" }; JComboBox formatList = new JComboBox(formats); formatList.addActionListener(this); leftPane.add(formatList, BorderLayout.NORTH); fileList = new JList(Files); fileList.setForeground(new Color(140,171,226)); fileList.setBackground(new Color(0,0,0)); fileList.setSelectionBackground(new Color(87,49,134)); fileList.setSelectionForeground(new Color(140,171,226)); JScrollPane scrollPane = new JScrollPane(fileList); scrollPane.setColumnHeaderView(new JLabel("wenj files")); leftPane.add(scrollPane, BorderLayout.CENTER); } contentPane.add(leftPane, BorderLayout.CENTER); pack(); Dimension d = Toolkit.getDefaultToolkit().getScreenSize(); setLocation(d.width/2 - getWidth()/2, d.height/2 - getHeight()/2); setVisible(true); } //设置菜单项 private void makeMenuBar() { final int SHORTCUT_MASK = Toolkit.getDefaultToolkit().getMenuShortcutKeyMask(); JMenuBar menubar = new JMenuBar(); setJMenuBar(menubar); JMenu menu; JMenuItem item; menu = new JMenu("File"); menubar.add(menu); item = new JMenuItem("Quit"); item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK)); item.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { quit(); } }); menu.add(item); menu = new JMenu("Help"); menubar.add(menu); item = new JMenuItem("About ..."); item.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { showAbout(); } }); menu.add(item); } }
界面图:
作业2:将游戏中最高纪录的玩家信息输出。
方法:这个可以利用seek()方法跳转指针和getFilePointer()方法来获取当前指针位置实现。
代码如下:
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
public class TestRandomAccessFile{ private File file; public static void main(String[] args){ TestRandomAccessFile traf = new TestRandomAccessFile(); traf.init(); traf.record("Adom",80); traf.listAllRecords(); } public void record(String record_breaker, int times){ try{ RandomAccessFile raf = new RandomAccessFile(file,"rw"); boolean flag = false; while(raf.getFilePointer() < raf.length()){ String name = raf.readUTF(); long prior = raf.getFilePointer(); if (record_breaker.equalsIgnoreCase(name)) { flag = true; //比较传递进来的数与之前数的大小 if (raf.readInt() < times) { //利用seek()方法跳转到prior的位置 raf.seek(prior); raf.writeInt(times); break; } } else { raf.skipBytes(4); } } if(!flag){ raf.writeUTF(record_breaker); raf.writeInt(times); } raf.close(); }catch(Exception e){ e.printStackTrace(); } } public void init(){ if(file == null){ file = new File("record.txt"); try{ file.createNewFile(); }catch(IOException e){ e.printStackTrace(); } } } public void listAllRecords(){ try{ RandomAccessFile raf = new RandomAccessFile(file,"r"); while(raf.getFilePointer() < raf.length()){ String name = raf.readUTF(); int times = raf.readInt(); System.out.println("name:" + name + "\trecord:" + times); } raf.close(); }catch(Exception e){ e.printStackTrace(); } } }
界面图:
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原文地址:http://www.cnblogs.com/lxwJava/p/5402159.html