Programmatically scroll a ScrollView to focus on a Button or a view - Android

Question

I have an Activity that has a ScrollView of 125 buttons. The 125 buttons are Levels in my game that slowly get unlocked (think of Candy Crush Saga). Right now if the user is on the level, let's say, 88 of 125 then the user has to manually scroll all the way down to button 88.

My question is, how would I make it so that when the Activity loads, it automatically scrolls down and centers the ScrollView on a certain button?

Below is my code of how the buttons are created and populated programmatically.

ScrollView scrollView;

@Override
public void onCreate(Bundle savedInstanceState) {


    LinearLayout lay = (LinearLayout)findViewById(R.id.linearlayout);

    for(int i = 0; i < 125; i++) {

        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, 0);
        params.weight = 1;
        params.gravity = Gravity.CENTER;

        if(i == 0) {
            TextView textview = new TextView(this);
            textview.setLayoutParams(params);
            textview.setTextSize(15);
            textview.setText(c.getResources().getString(R.string.l1to5));

            TextView textview2 = new TextView(this);
            textview2.setLayoutParams(params);
            textview.setTextSize(15);
            textview2.setText(c.getResources().getString(R.string.goal100));

            TextView textview3 = new TextView(this);
            textview3.setLayoutParams(params);
            textview.setTextSize(15);
            textview3.setText(c.getResources().getString(R.string.catRandom));

            if((getResources().getConfiguration().screenLayout & 
                Configuration.SCREENLAYOUT_SIZE_MASK) == 
                Configuration.SCREENLAYOUT_SIZE_LARGE) {
                    textview.setTextSize(22);
                    textview2.setTextSize(22);
                    textview3.setTextSize(22);
            } else if((getResources().getConfiguration().screenLayout & 
                Configuration.SCREENLAYOUT_SIZE_MASK) == 
                Configuration.SCREENLAYOUT_SIZE_XLARGE) {
                    textview.setTextSize(22);
                    textview2.setTextSize(22);
                    textview3.setTextSize(22);
            }

            lay.addView(textview);
            lay.addView(textview2);
            lay.addView(textview3);     

            View ruler = new View(this);
            ruler.setBackgroundColor(0xFFC2BEBF);
            lay.addView(ruler, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, 2));
        }

        if(i == 5) {

 //  ....

}



        Button button = new Button(this);
        int _id = getResources().getIdentifier("b" + (i + 1), "id", this.getPackageName());
        button.setTag(_id);
        button.setLayoutParams(params);

        if((getResources().getConfiguration().screenLayout & 
            Configuration.SCREENLAYOUT_SIZE_MASK) == 
            Configuration.SCREENLAYOUT_SIZE_LARGE) {
                button.setTextSize(22);
        } else if((getResources().getConfiguration().screenLayout & 
            Configuration.SCREENLAYOUT_SIZE_MASK) == 
            Configuration.SCREENLAYOUT_SIZE_XLARGE) {
                button.setTextSize(22);
        }

        button.setText("Level " + (i + 1));
        final int x = i + 1;
        button.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                singleton.setLevelJustPlayed(x);
                // ...
                } else {
                 // ...
                    Intent intent = new Intent(Levels.this, Categories.class);
                    startActivity(intent);
                }
            }
        });

        lay.addView(button);

        if(singleton.getLevel() >= (i + 1)) {
            button.setEnabled(true);
        } else {
            button.setEnabled(false);
        }
    }
// end the onCreate() method

Solution 1

try

yourScrollView.scrollTo(0, (int) button.getY());

Solution 2

For Kotlin user

your_scrollview.post( { your_scrollview.scrollTo(0, your_view_inside_SV.getY().toInt()) })

Comments

[Matt]

Ah ok, that is what I am looking for. What is the getY() referring to, though?

[trippedout]

getY() - should be more than enough to find out where the button is lying in your scroll view

[Zin Win Htet]

It works, but it didn't work with smoothScrollBy => new Handler().post(new Runnable() { @Override public void run() { scrollView.smoothScrollBy(0, centreY); } });