How to set a timer in android

Standard Java way to use timers via java.util.Timer and java.util.TimerTask works fine in Android, but you should be aware that this method creates a new thread.

You may consider using the very convenient Handler class (android.os.Handler) and send messages to the handler via sendMessageAtTime(android.os.Message, long) or sendMessageDelayed(android.os.Message, long). Once you receive a message, you can run desired tasks. Second option would be to create a Runnable object and schedule it via Handler's functions postAtTime(java.lang.Runnable, long) or postDelayed(java.lang.Runnable, long).

As I have seen it, java.util.Timer is the most used for implementing a timer.

For a repeating task:

new Timer().scheduleAtFixedRate(task, after, interval);

For a single run of a task:

new Timer().schedule(task, after);

task being the method to be executed
after the time to initial execution
(interval the time for repeating the execution)

yes java's timer can be used, but as the question asks for better way (for mobile). Which is explained Here.

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For the sake of StackOverflow:

Since Timer creates a new thread it may be considered heavy,

if all you need is to get is a call back while the activity is running a Handler can be used in conjunction with a

Runnable:

private final int interval = 1000; // 1 Second
private Handler handler = new Handler();
private Runnable runnable = new Runnable(){
    public void run() {
        Toast.makeText(MyActivity.this, "C'Mom no hands!", Toast.LENGTH_SHORT).show();
    }
};
...
handler.postAtTime(runnable, System.currentTimeMillis()+interval);
handler.postDelayed(runnable, interval);

or a Message

private final int EVENT1 = 1; 
private Handler handler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {         
        case Event1:
            Toast.makeText(MyActivity.this, "Event 1", Toast.LENGTH_SHORT).show();
            break;
        
        default:
            Toast.makeText(MyActivity.this, "Unhandled", Toast.LENGTH_SHORT).show();
            break;
        }
    }
};

...

Message msg = handler.obtainMessage(EVENT1);
handler.sendMessageAtTime(msg, System.currentTimeMillis()+interval);
handler.sendMessageDelayed(msg, interval);

on a side note this approach can be used, if you want to run a piece of code in the UI thread from an another thread.

WARNING: Handler's timer (or whatever controls delays) gets paused whenever the CPU goes to deep-sleep, but will continue once CPU wakes up (from where it was paused).

if you need to get a call back even if your activity is not running then, you can use an AlarmManager.