Android Java: .setText() every x ms

Question

I want to do the following: I give a String to a global function in my App and this function opens a FrameLayout that looks like a speech bubble. This one includes a TextView for the String. Works pretty well so far - but I want it to look like a "live speech". So the text shouldn't just appear, but every single character after x miliseconds. Like:
H
He
Hel
Hell
(etc.)

Do you have any ideas for that? Thanks!

Answer 1

I've written a class extending AsyncTask as a quick example of how you can do this:

public class TyperTask extends AsyncTask<Void, String, Void> {
    TextView mTextView;
    String mMessage;
    int mTypingDelay;

    TyperTask(TextView textView, String message, int typingDelay) {
        this.mTextView = textView;
        this.mMessage = message;
        this.mTypingDelay = typingDelay;
    }

    @Override
    protected Void doInBackground(Void... params) {
        for (int i = 0; i < mMessage.length(); i++) {
            publishProgress(String.valueOf(mMessage.charAt(i)));
            try {
                Thread.sleep(mTypingDelay);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    @Override
    protected void onProgressUpdate(String... typedChar) {
        mTextView.append(typedChar[0]);
    }

}

Here's how to use it:

TextView myTextView = (TextView) findViewById(R.id.myTextView);
new TyperTask(myTextView, "This is a test message.", 100).execute();