Handler in Android

Overview

Handler allows you to send Message and process Runnable objects which are associated with the thread of a Message Queue. 

Steps to create a Handler with Message

 final Handler handler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        super.handleMessage(msg);
        char c = s.charAt(i[0]);
        bottomText.append(String.valueOf(c)); //bottomText is a TextView
        i[0]++;
    }
 };
 final Timer timer = new Timer();
 TimerTask taskEverySplitSecond = new TimerTask() {
    @Override
    public void run() {
        handler.sendEmptyMessage(0);
        if (i[0] == length - 1) {
            timer.cancel();
        }
    }
 };
 timer.schedule(taskEverySplitSecond, 1, 500);

The above code throws a warning "This Handler class should be static" replace the code with the below code.

 final Handler handler = new Handler(msg -> {
    char c = s.charAt(i[0]);
    bottomtext.append(String.valueOf(c)); //bottomText is a TextView
    i[0]++;
    return false;
 });
 final Timer timer = new Timer();
 TimerTask taskEverySplitSecond = new TimerTask() {
    @Override
    public void run() {
        handler.sendEmptyMessage(0);
        if (i[0] == length - 1) {
            timer.cancel();
        }
    }
 };
 timer.schedule(taskEverySplitSecond, 1, 500);

Steps to create Handler with postDelayed()

 new Handler().postDelayed(new Runnable() {
    @Override
    public void run() {
        Intent intent = new Intent(MainActivity.this, LoginPage.class);
        startActivity(intent);
        finish();
        overridePendingTransition(R.anim.fadein, R.anim.fadeout);
    }
 }, 5000);

Reference

1. https://stackoverflow.com/questions/61023968/what-do-i-use-now-that-handler-is-deprecated