The Method ScrollTo has no use

I made a android program to read books.. And I want to make it possible to open a tag ,and when you open a tag, the program will open the book and scroll to the position which is told in the tag .

But in my app,the ScrollTo function seems no reaction .

Here is my code.

protected void onCreate(Bundle savedInstanceState) {
        sup开发者_如何学JAVAer.onCreate(savedInstanceState);
        setContentView(R.layout.reader);

        scrollView = (ScrollView)findViewById(R.id.Scroll);
        text       = (TextView)findViewById(R.id.text);
        tagsButton = (ImageButton)findViewById(R.id.Tags);
        openButton = (ImageButton)findViewById(R.id.Open);

        text.setTextColor(Color.RED);
        text.scrollTo(0, index);
    }//Here the scrollTo do not work...

The process in onCreate is not important ,so I delete them..

What is puzzling me is that in the method below the method scroll can work...

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(data!=null){
        Bundle bundle = data.getExtras();
        if(bundle!=null){
        int index = bundle.getInt("Index");
        String file_name = bundle.getString("File_Name");


        ReadFile(file_name);
        scrollView.scrollTo(0, index);
        text.postInvalidate();
        }
        }

I don't think there's so much difference between these two methods...But why...

Anyone can help me?

THX a lot.

in your onCreate try

 text.post(new Runnable() {
        @Override
        public void run() {  
            text.scrollTo(...);
        }
    });