How to encrypt a serializable class in Android

public boolean save(YourClass pref){

boolean isSuccess = false;

try {

final File persistedFile = new File("/sdcard/sr.dat");

if(persistedFile.exists())

persistedFile.delete();

OutputStream file = new FileOutputStream(persistedFile);

BufferedOutputStream buffer = new BufferedOutputStream(file);

Cipher desCipher = getCipher(Cipher.ENCRYPT_MODE);

CipherOutputStream cos = new CipherOutputStream(buffer, desCipher);

ObjectOutputStream oos = new ObjectOutputStream(cos);

oos.writeObject(pref);

oos.flush();

oos.close();

} catch (IOException ex) {

Log.d(TAG, ex.getMessage());

isSuccess = false;

} catch (InvalidKeyException e) {

Log.d(TAG, e.getMessage());

isSuccess = false;

} catch (InvalidKeySpecException e) {

Log.d(TAG, e.getMessage());

isSuccess = false;

} catch (NoSuchAlgorithmException e) {

Log.d(TAG, e.getMessage());

isSuccess = false;

} catch (NoSuchPaddingException e) {

Log.d(TAG, e.getMessage());

isSuccess = false;

}

return isSuccess;

}

private Cipher getCipher(int opmode) throws InvalidKeyException, InvalidKeySpecException, NoSuchAlgorithmException, NoSuchPaddingException {

byte key[] = "Aruna Tennakoon".getBytes();

DESKeySpec desKeySpec = new DESKeySpec(key);

SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");

SecretKey secretKey = keyFactory.generateSecret(desKeySpec);

// Create Cipher

Cipher desCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");

desCipher.init(opmode, secretKey);

return desCipher;

}

public Preference load(){

Preference repo = null;

try {

final File persistedFile = File("/sdcard/sr.dat");

if(!persistedFile.exists()) {

// sr is not created yet. Create one and return

return;

}

Cipher desCipher = getCipher(Cipher.DECRYPT_MODE);

FileInputStream fis = new FileInputStream(persistedFile.getAbsolutePath());

BufferedInputStream bis = new BufferedInputStream(fis);

CipherInputStream cis = new CipherInputStream(bis, desCipher);

ObjectInputStream ois = new ObjectInputStream(cis);

repo = (YourClass) ois.readObject();

ois.close();

} catch (FileNotFoundException e) {

Log.d(TAG, e.getMessage());

} catch (StreamCorruptedException e) {

Log.d(TAG, e.getMessage());

} catch (IOException e) {

Log.d(TAG, e.getMessage());

} catch (InvalidKeyException e) {

Log.d(TAG, e.getMessage());

} catch (InvalidKeySpecException e) {

Log.d(TAG, e.getMessage());

} catch (NoSuchAlgorithmException e) {

Log.d(TAG, e.getMessage());

} catch (NoSuchPaddingException e) {

Log.d(TAG, e.getMessage());

} catch (ClassNotFoundException e) {

Log.d(TAG, e.printStackTrace());

}

return repo;

}

how to get the ip address of android phone?

private String getLocalIpAddress() {

try {

for (Enumeration en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements();) {

NetworkInterface intf = en.nextElement();

for (Enumeration enumIpAddr = intf.getInetAddresses(); enumIpAddr.hasMoreElements();) {

InetAddress inetAddress = enumIpAddr.nextElement();

if (!inetAddress.isLoopbackAddress()) { return inetAddress.getHostAddress().toString(); }

}

}

} catch (SocketException ex) {

Log.e("ServerActivity", ex.toString());

}

return null;

}

'Conversion to Dalvik format failed with error 1' and 'java.lang.IllegalArgumentException: already added: '

Recently we moved to Android SDK tools Rev 15 , In my opinion it has may problems comparing to previous versions of the SDK and should stick with the previous version if you are developing a huge applications and have library projects referenced.

Today, I got this error and few hours of Googling found the solution,

Remove the source folder link in Project properties->Java Build Path->Source

Clean and add the projects back, You will see that it will add the projects as jar files under "Library Projects" not as project_src anymore.

How to do a simple visible animation in Android

public void showConfigurationBar() {

AnimationSet set = new AnimationSet(true);

Animation animation = new AlphaAnimation(0.0f, 1.0f);

animation.setDuration(500);

set.addAnimation(animation);

animation = new TranslateAnimation(Animation.RELATIVE_TO_SELF, 0.0f,

Animation.RELATIVE_TO_SELF, 0.0f, Animation.RELATIVE_TO_SELF,

1.0f, Animation.RELATIVE_TO_SELF, 0.0f);

animation.setDuration(500);

set.addAnimation(animation);

RelativeLayout configBar = findViewById(R.id.baridhere);

configBar.setVisibility(View.VISIBLE);

configBar.startAnimation(set);

}

How to generate a MD5 Hash in Android

public static String getMd5Hash(String input) {

try {

MessageDigest md = MessageDigest.getInstance("MD5");

byte[] messageDigest = md.digest(input.getBytes());

BigInteger number = new BigInteger(1, messageDigest);

String md5 = number.toString(16);

while (md5.length() < 32)

md5 = "0" + md5;

return md5;

} catch (NoSuchAlgorithmException e) {

Log.e("MD5", e.getLocalizedMessage());

return null;

}

}

Eclipse Layout Editor Graphical Layout is not Showing or missing ?

Specify the Android Layout Editor as the default for Android XML files under Preferences -> General- >Editors->File Associations.

1. If Android layout editor is missing Add Android Layout Editor and make it default.

2. Close eclipse and restart. Otherwise this will not work.