Android snippet: validate a hex number input

This is how you can validate a hex input in android code. The regex it makes use of can be used in other languages as well.

Validation steps are :

  • check if the input is not null or zero length
  • check if the input has even numbers as hex numbers are always even
  • match the input with the validating regex.
public boolean validHexInput(String str) {

   if (str == null || str.length() == 0) {
      return false;
   }

   // length should be even number 
   // otherwise its not a valid hex 
   if (str.length() % 2 == 0) {
      String var1 = "(?i)[0-9a-f]+";
      return str.matches(var1);
 }

 return false;
}

 

Converting UNIX timestamp to seconds, minutes, hours, days, weeks, month, years, decades ago

If you have UNIX time-stamps and you want convert it to show how may seconds, minutes, hours, weeks, months, years or decades ago it is from now you may use the following snippet of code. It accepts UNIX time-stamp in long format, In case you are getting UNIX time-stamps in String format you have to convert it to long. It will return a string with either seconds, minutes , hours , days, weeks, months, years , or decades ago. The code is written in java for an android app but can be ported to any language. Here is the code which is also available on github.

 

 

 

How to play ringtone/alarm/notification sound in Android

Playing the default notification sound of the device is the most effective way to notify a user. This can be established by getting the Uri of the audio file from RingtoneManager. To play default alarm tone , ringtone or notification sound from an android app, the following code snippet is useful.

Play Notification Tone

try {
 Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
 Ringtone r = RingtoneManager.getRingtone(getApplicationContext(), notification);
 r.play();
 } catch (Exception e) {
 e.printStackTrace();
 }

Play Alarm Tone

To play an Alarm-tone change TYPE_NOTIFICATION to TYPE_ALARM.

try {
 Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
 Ringtone r = RingtoneManager.getRingtone(getApplicationContext(), notification);
 r.play();
 } catch (Exception e) {
 e.printStackTrace();
 }

Set & Play a Tone from Raw resources folder

To set a file from the raw folder of your app just change the uri to get the desired file from raw resources. If you have included a tone called sownd.mp3 in your raw resources folder, all you have to do is change

 Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);

to

  Uri path = Uri.parse("android.resource://"+getPackageName()+"/raw/sound.mp3");

The code should look like this now

try {
  Uri path = Uri.parse("android.resource://"+getPackageName()+"/raw/sound.mp3");
  // The line below will set it as a default ring tone replace
  // RingtoneManager.TYPE_RINGTONE with RingtoneManager.TYPE_NOTIFICATION
  // to set it as a notification tone
  RingtoneManager.setActualDefaultRingtoneUri(
                    getApplicationContext(), RingtoneManager.TYPE_RINGTONE,
                    path);
  Ringtone r = RingtoneManager.getRingtone(getApplicationContext(), path); 
  r.play();
 } 
catch (Exception e) {
 e.printStackTrace(); 
}