Checking memory card in Java ME
This code snippet demonstrates how to check memory card availability.
Article Metadata
Code Example
Source file: Media:Checking memory card in Java ME.zip
Tested with
Devices(s): Nokia 6131, Nokia N80, Nokia N81, Nokia 701, Nokia Asha 305
Compatibility
Platform(s): Series 40, Symbian
Article
Keywords: java.lang.System.getProperty(), javax.microedition.io.Connector.open(), javax.microedition.io.file.FileConnection.availableSize()
Created: olkazmin
(27 Nov 2008)
Last edited: hamishwillee
(05 Oct 2012)
Contents |
Overview
The application uses the System.getProperty method to check the API version and memory card drive path.
After the path has been retrieved, the application establishes a file connection using the Connector.open method and gets the amount of space available on the memory card by calling FileConnection.availableSize.
Source file: CheckingMemoryCard.java
import javax.microedition.io.Connector;
import javax.microedition.io.file.FileConnection;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
/**
* MIDP is an example checking memory card availability.
*/
public class CheckingMemoryCard extends MIDlet implements CommandListener {
private Display display;
/**
* For displaying results.
*/
private Form frmMain;
/**
* Calls exitMIDlet method.
*/
private Command cmdExit;
/**
* Starts MC-checking procedure.
*/
private Command cmdCheck;
/**
* Constructor. Constructs the object and initializes displayables.
*/
public CheckingMemoryCard() {
InitializeComponents();
}
/**
* Initializes a ListBox object and adds softkeys.
*/
protected void InitializeComponents() {
display = Display.getDisplay( this );
//initializing device list
frmMain = new Form( "MC Info" );
cmdExit = new Command( "Exit", Command.EXIT, 1 );
cmdCheck = new Command( "Check", Command.SCREEN, 1);
frmMain.addCommand( cmdExit );
frmMain.addCommand( cmdCheck );
frmMain.setCommandListener( this );
}
/**
* From MIDlet.
* Called when MIDlet is started.
* @throws javax.microedition.midlet.MIDletStateChangeException
*/
public void startApp() throws MIDletStateChangeException {
display.setCurrent( frmMain );
}
/**
* From MIDlet.
* Called to signal the MIDlet to enter the Paused state.
*/
public void pauseApp() {
//No implementation required
}
/**
* From MIDlet.
* Called to signal the MIDlet to terminate.
* @param unconditional whether the MIDlet has to be unconditionally
* terminated
* @throws javax.microedition.midlet.MIDletStateChangeException
*/
public void destroyApp(boolean unconditional)
throws MIDletStateChangeException {
exitMIDlet();
}
/**
* From CommandListener.
* Called by the system to indicate that a command has been invoked on a
* particular displayable.
* @param command the command that was invoked
* @param displayable the displayable where the command was invoked
*/
public void commandAction( Command command, Displayable displayable ) {
if( command == cmdExit ) {
exitMIDlet();
}
if( command == cmdCheck ) {
//checking API version
if( !checkAPIVersion() )
return;
//getting Localized UI name for the memory card
checkMCDirName();
//checking Root directory of a memory card
if( !checkMCRoot() )
return;
//if Root directory retrieved in the previous step
//then we do a file connection test
checkMCConnection();
}
}
/**
* Method calls stopDiscover method and notifyDestroyed after that.
*/
protected void exitMIDlet() {
notifyDestroyed();
}
/**
* Adds a StringItem to the frmMain.
* @param strPrint string to add to frmMain.
* @see Form#append(java.lang.String)
* @see Form
*/
protected void printToFrm( String strPrint ) {
frmMain.append( strPrint );
}
/**
* Gets JSR-75 API version using MIDP system property and
* check whether it is null or not.
* @return true if version detected and false otherwise.
*/
protected boolean checkAPIVersion() {
String fileconVer =
System.getProperty(
"microedition.io.file.FileConnection.version" );
printToFrm( "Getting JSR-75 API version..." );
if( fileconVer != null ) {
printToFrm( "Version : " + fileconVer );
} else {
printToFrm( "Version NOT found!");
return false;
}
return true;
}
/**
* Gets Localized MC directory name using MIDP system property and
* check whether it is null or not.
* @return true if name detected and false otherwise.
*/
private boolean checkMCDirName() {
String nameMC = System.getProperty( "fileconn.dir.memorycard.name" );
printToFrm( "Getting MC directory name ..." );
if( nameMC != null ) {
printToFrm( "MC directory name : " + nameMC );
} else {
printToFrm( "MC directory name NOT found!");
return false;
}
return true;
}
/**
* Gets MC directory connection URL using MIDP system property and
* check whether it is null or not.
* @return true if URL detected and false otherwise.
*/
private boolean checkMCRoot() {
String rootMC = System.getProperty( "fileconn.dir.memorycard" );
printToFrm( "Getting MC root ..." );
if( rootMC != null ) {
printToFrm( "MC root : " + rootMC );
} else {
printToFrm( "MC root NOT found!");
return false;
}
return true;
}
/**
* Gets MC directory connection URL using MIDP system property and
* check whether it is null or not.
* @return true if URL detected and false otherwise.
*/
private boolean checkMCConnection() {
String rootMC = System.getProperty( "fileconn.dir.memorycard" );
FileConnection fconn = null;
try {
fconn = (FileConnection)Connector.open( rootMC );
printToFrm( "Getting available size ...");
printToFrm( "Size: " + ( fconn.availableSize() / 1024 ) + "KB" );
printToFrm( "Closing file connection...");
fconn.close();
} catch ( Exception e ) {
printToFrm( e.toString() );
return false;
}
return true;
}
}
Postconditions
When the Check command is pressed, the following steps are performed:
- API availability check. If available, it is printed to the form.
- Getting Localized UI name for the memory card. If found, it is printed to the form.
- Checking Root directory of a memory card. If found, it is printed to the form.
- File connection test. The available size is printed to the form if the connection
was successful.
Supplementary material
The source file and executable application are available for download at Media:Checking memory card in Java ME.zip.
