一个Java记事本程序

小灰灰 2024-03-24 16:14 58阅读 0赞

import java.io.BufferedReader;  
import java.io.File;  
import java.io.FileReader;  
import java.io.FileWriter;  
import java.io.IOException;  
import javax.swing.JFileChooser;  
import javax.swing.JFrame;  
import javax.swing.JOptionPane;  
import javax.swing.JScrollPane;  
import javax.swing.JTextArea;

public class JavaNote \{

private JTextArea textArea;  
private JFileChooser fileChooser;  
private String fileName;

public static void main(String\[\] args) \{  
new JavaNote();  
\}

public JavaNote() \{

JFrame frame = new JFrame("JavaNote");

// create a new JTextArea  
textArea = new JTextArea();

// add a JScrollPane to the JTextArea  
JScrollPane scrollPane = new JScrollPane(textArea,  
JScrollPane.VERTICAL\_SCROLLBAR\_ALWAYS,  
JScrollPane.HORIZONTAL\_SCROLLBAR\_ALWAYS);

// add the JScrollPane to the JFrame  
frame.add(scrollPane);

// create a new JFileChooser  
fileChooser = new JFileChooser();

// set the default directory  
fileChooser.setCurrentDirectory(new File("."));

// create a new menu bar  
MenuBar menuBar = new MenuBar(this);

// set the menu bar of the JFrame  
frame.setJMenuBar(menuBar);

// set the size of the JFrame  
frame.setSize(800, 600);

// make the JFrame visible  
frame.setVisible(true);

// method to create a new file  
public void newFile() \{

// clear the text area  
textArea.setText("");

// set the name of the file to null  
fileName = null;

// method to open a file  
public void openFile() \{

// show the open file dialog  
int result = fileChooser.showOpenDialog(null);

// check if a file was selected  
if (result == JFileChooser.APPROVE\_OPTION) \{

// get the selected file  
File file = fileChooser.getSelectedFile();

// set the name of the file  
fileName = file.getName();

try \{

// read the contents of the file  
FileReader reader = new FileReader(file);  
BufferedReader br = new BufferedReader(reader);  
textArea.read(br, null);  
br.close();  
textArea.requestFocus();

\} catch (IOException ex) \{

// display an error message  
JOptionPane.showMessageDialog(null,  
"Error opening file: " + ex.getMessage(),  
"Error", JOptionPane.ERROR\_MESSAGE);

\}  
\}  
\}

// method to save a file  
public void saveFile() \{

// check if the file name is null  
if (fileName == null) \{

// show the save file dialog  
int result = fileChooser.showSaveDialog(null);

// check if a file was selected  
if (result == JFileChooser.APPROVE\_OPTION) \{

// get the selected file  
File file = fileChooser.getSelectedFile();

try \{

// save the contents of the file  
FileWriter writer = new FileWriter(file);  
textArea.write(writer);  
writer.close();  
fileName = file.getName();

\} catch (IOException ex) \{

// display an error message  
JOptionPane.showMessageDialog(null,  
"Error saving file: " + ex.getMessage(),  
"Error", JOptionPane.ERROR\_MESSAGE);