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Revision as of 13:08, 3 June 2009 by jarmlaht (Talk | contribs)

How to write data to a file in Java ME

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Article Metadata
Tested with
Devices(s): Emulator
CompatibilityArticle
Keywords: textBox,Commndbutton,String,FileConnection
Created: (28 Jan 2009)
Last edited: jarmlaht (03 Jun 2009)

Overview

This article shows, how to write data to a file by using FileConnection API (JSR-75). This example MIDlet has a TextBox, where text can be entered. Then the text can be saved to readme.txt file, which is in this case created under Gallery's Images folder.


The full source code for a test MIDlet:

Source code: WriteMIDlet.java

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.io.file.*;
import javax.microedition.io.*;
import java.io.*;
 
public class WriteMIDlet extends MIDlet implements CommandListener {
private TextBox textbox;
private String photos = "fileconn.dir.photos";
private Command saveCommand;
private Command exitCommand;
private String path;
 
public void startApp() {
textbox = new TextBox("WriteMIDlet", "", 1000, TextField.ANY);
saveCommand = new Command("Save", Command.SCREEN, 1);
exitCommand = new Command("Exit", Command.EXIT, 1);
textbox.addCommand(saveCommand);
textbox.addCommand(exitCommand);
textbox.setCommandListener(this);
Display.getDisplay(this).setCurrent(textbox);
path = System.getProperty(photos);
}
 
public void pauseApp() {
}
 
public void destroyApp(boolean unconditional) {
}
 
private void saveFile(String path, String name) {
try {
String url = path + name;
String string = textbox.getString();
byte data[] = string.getBytes();
FileConnection fconn = (FileConnection)Connector.open(url, Connector.READ_WRITE);
if (!fconn.exists()) {
fconn.create();
}
OutputStream ops = fconn.openOutputStream();
ops.write(data);
ops.close();
fconn.close();
}
catch (IOException ioe) {
System.out.println("IOException: "+ioe.getMessage());
}
catch (SecurityException se) {
System.out.println("Security exception:" + se.getMessage());
}
}
 
public void commandAction(Command c, Displayable d) {
if (c == saveCommand) saveFile(path, "readme.txt");
if (c == exitCommand) this.notifyDestroyed();
}
}

See also

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