How to write data to a file in Java ME

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:

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();
 } 
}