Save my notepad!

shaozhikun

I wrote a simple notepad using JAVA. Can anyone tell me how to determine whether the content in JTextArea has changed?

ekinzou

change event

shaomon

Add an ActionListener

shaozhikun

Can you be more specific, is it ChangeListener, but there is no addChangeListener in JTextArea

bevande

The java.awt.TextArea could be monitored for changes by adding a TextListener for TextEvents. In the JTextComponent based components, changes are broadcasted from the model via a DocumentEvent to DocumentListeners. The DocumentEvent gives the location of the change and the kind of change if desired. The code fragment might look something like:

    DocumentListener myListener = ??;
    JTextArea myArea = ??;
    myArea.getDocument().addDocumentListener(myListener);

api original

http://java.sun.com/j2se/1.5.0/docs/api/javax/swing/JTextArea.html

shaozhikun

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;


class NotepadJFrame extends JFrame {
JScrollPane jsp;
JTextArea jta;
boolean motified = false;
String currentFileName = null;
The
NotepadJFrame() {
setProp();
addComponent();
this.setVisible(true);
}
The
private void setProp() {
this.setSize(500, 400);
this.setLocation(200, 100);
this.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
this.setTitle("My Notepad");
this.setJMenuBar(new NoteMenuBar(this));
this.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
close();
}
});
}
The
private void addComponent() {
jsp = new JScrollPane();
jta = new JTextArea();
jsp.getViewport().add(jta);
this.getContentPane().add(jsp, BorderLayout.CENTER);
jta.getDocument().addDocumentListener(new DocumentListener() {
public void insertUpdate(DocumentEvent e) {
motified = true;
}
public void removeUpdate(DocumentEvent e) {
motified = true;
}
public void changedUpdate(DocumentEvent e) {
motified = true;
}
});
}
The
void close() {
if(motified) {
int rst = JOptionPane.showConfirmDialog(null, "Do you want to save");
switch(rst){
case JOptionPane.YES_OPTION:
save();
break;
case JOptionPane.NO_OPTION: System.exit(0);
case JOptionPane.CANCEL_OPTION:
}
} else {
System.exit(0);
}
}
The
void open() {
JFileChooser jfc = new JFileChooser();
jfc.showOpenDialog(null);
File f = jfc.getSelectedFile();
try {
FileReader fr = new FileReader(f);
BufferedReader br = new BufferedReader(fr);
String tmp;
StringBuffer all = new StringBuffer();
while(!(tmp = br.readLine()).trim().equals("")) {
all.append(tmp);
all.append("\n");
}
br.close();
fr.close();
this.jta.setText(all.toString());
}catch(IOException e) {
e.printStackTrace();
}
}
The
void save() {
try {
if(currentFileName==null) {
saveAsFile();
}
FileWriter fw = new FileWriter(this.currentFileName);
BufferedWriter bw = new BufferedWriter(fw);
String[] all = this.jta.getText().split("\n");
for(int i=0;i<all.length;i++) {
bw.write(all[i]);
bw.newLine();
}
bw.flush();
bw.close();
fw.close();
motified=false;
}catch(IOException e) {
e.printStackTrace();
}
}
The
void saveAsFile() {
JFileChooser chooser = new JFileChooser("c:/");
chooser.showSaveDialog(null);
this.currentFileName = chooser.getSelectedFile().getPath();
save();
}
The
void newFile() {
if(motified) {
int rst = JOptionPane.showConfirmDialog(null, "Do you want to save");
switch(rst){
case JOptionPane.YES_OPTION:
save();
break;
case JOptionPane.NO_OPTION:
case JOptionPane.CANCEL_OPTION:
}
}
jta.setText("");
motified = false;
}
}

shaozhikun

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;


class NoteMenuBar extends JMenuBar {
private JMenu menuFile;
private JMenuItem[] items;
private NotepadJFrame njf;
NoteMenuBar(NotepadJFrame njf) {
super();
this.njf = njf;
addMenuContent();
}
The
private void addMenuContent() {
menuFile = new JMenu("File");
this.add(menuFile);
items = new JMenuItem[5];
String[] strItem = {"New", "Open", "Save", "Save As", "Close"};
for (int i = 0; i <items.length; i ++) {
items[i] = new JMenuItem(strItem[i]);
if ("Close".equals(strItem[i])) {
menuFile.addSeparator();
}
items[i].addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String strCmd = e.getActionCommand();
if("New".equals(strCmd)) {
njf.newFile();
} else if ("open".equals(strCmd)) {
njf.open();
} else if("Save".equals(strCmd)) {
njf.save();
} else if("Save as".equals(strCmd)) {
njf.saveAsFile();
} else if ("Close".equals(strCmd)) {
njf.close();
}
}
});
menuFile.add(items[i]);
}
}
}

shaozhikun

A simple notepad, let's take a look and give some advice, see if it can be modified better

bevande

Increase timing automatic save

shaozhikun

I want to add a cut, copy, and paste menu item, and how to create a right-click menu. The expert will give you directions