Typewriter Animation in Android TextView.

Here is a simple class to animate a textview just like a Typewriter.

Typewriter

package typ_tv.coderzheaven.com.typewritertextview;

import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.TextView;

public class Typewriter extends TextView {

    private static final String TAG = Typewriter.class.getSimpleName();
    private CharSequence mText;
    private int mIndex;
    private long mDelay = 500; // Default 500ms character delay
    Handler animationCompleteCallBack;

    public Typewriter(Context context) {
        super(context);
    }

    public void setAnimationCompleteListener(Handler animationCompleteCallBack) {
        this.animationCompleteCallBack = animationCompleteCallBack;
    }

    public Typewriter(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    private Handler mHandler = new Handler();
    private Runnable characterAdder = new Runnable() {
        @Override
        public void run() {
            setText(mText.subSequence(0, mIndex++));
            if (mIndex <= mText.length()) {
                mHandler.postDelayed(characterAdder, mDelay);
            } else {
                if (null != animationCompleteCallBack)
                    animationCompleteCallBack.sendMessage(new Message());
                else
                    Log.i(TAG, "Animation Complete Listener not set...");
            }
        }
    };

    public void animateText(CharSequence text) {
        mText = text;
        mIndex = 0;
        setText("");
        mHandler.removeCallbacks(characterAdder);
        mHandler.postDelayed(characterAdder, mDelay);
    }

    public void setCharacterDelay(long millis) {
        mDelay = millis;
    }
}

Usage

package typ_tv.coderzheaven.com.typewritertextview;

import android.graphics.Typeface;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Handler animationCompleteCallBack = new Handler(new Handler.Callback() {
            @Override
            public boolean handleMessage(Message msg) {
                Log.i("Log", "Animation Completed");
                return false;
            }
        });

        Typewriter typewriter = new Typewriter(this);
        typewriter.setCharacterDelay(100);
        typewriter.setTextSize(30);
        typewriter.setTypeface(null, Typeface.BOLD);
        typewriter.setPadding(20, 20, 20, 20);
        typewriter.setAnimationCompleteListener(animationCompleteCallBack);
        typewriter.animateText("CoderzHeaven\nHeaven of all working codes");

        setContentView(typewriter);
    }
}

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