Android character by character display text animation

This may not be the most elegant solution, but the simplest is probably a quick subclass of TextView with a Handler that updates the text every so often until the complete sequence is displayed:
 

public class Typewriter extends TextView {

    private CharSequence mText;
    private int mIndex;
    private long mDelay = 500; //Default 500ms delay


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

    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);
            }
        }
    };

    public void animateText(CharSequence text) {
        mText = text;
        mIndex = 0;

        setText("");
        mHandler.removeCallbacks(characterAdder);
        mHandler.postDelayed(characterAdder, mDelay);
    }

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

You can then use this in an Activity like so:

public class MyActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Typewriter writer = new Typewriter(this);
        setContentView(writer);

        //Add a character every 150ms
        writer.setCharacterDelay(150);
        writer.animateText("Sample String");
    }
}

If you want some animation effects with each letter added, perhaps look at subclassing TextSwitcher instead.
Hope that Helps!

There are many ways to show the characters using "string.xml".
/* One method to get the characters from String*/
writer.animateText(getString(R.string.poem_one)); //get the text from string.xml
       
/* One more method to retrieve the character from String*/
CharSequence  cs = getText(R.string.poem_one);
writer.animateText(cs);

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How to create Ticker (marquee text)

If you want marquee text in your application, here is the simplest example.

In your xml-layout file, add this to your TextView

android:singleLine="true"
android:ellipsize="marquee"
android:marqueeRepeatLimit="marquee_forever"

and in your code to start animation:

TextView tv = (TextView) findViewById(R.id.tv);
tv.setSelected(true);

Via the API:

http://developer.android.com/reference/android/widget/TextView.html#attr_android:ellipsize

http://developer.android.com/reference/android/widget/TextView.html#attr_android:marqueeRepeatLimit

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