Button in ViewPager scroll to specific page

Question

One of my layouts inside of my ViewPager has a button. "R.layout.add_site". I would like the option of hitting the button and it scroll to the specific page for me. I already have the option to swipe to the specific page, but I would like to have both.

Now I'm sure there's a way to do that, but for some reason, I cannot figure it out.

You'll see that I've made an attempt , but just dont know what method to call in order to make it scroll to the desired page. Which is R.layout.main.

Here's my code.

public class fieldsActivity extends Activity {

Button addSiteButton;
Button cancelButton;
Button signInButton;

/**
 * Called when the activity is first created.
 */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // to create a custom title bar for activity window
    requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);

    setContentView(R.layout.fields);
    // use custom layout title bar
    getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.topbar);

    Pager adapter = new Pager();
    ViewPager mPager = (ViewPager) findViewById(R.id.fieldspager);
    mPager.setAdapter(adapter);
    mPager.setCurrentItem(1);


    addSiteButton = (Button) findViewById(R.id.addSiteButton);
    addSiteButton.setOnClickListener(new View.OnClickListener() {


        @Override
        public void onClick(View v) {
        // Don't know what method to call!?



        }


    });


    cancelButton = (Button) findViewById(R.id.cancel_button);
    signInButton = (Button) findViewById(R.id.sign_in_button);

}

 private class Pager extends PagerAdapter {
    public int getCount() {
        return 3;

    }

    @Override
    public Object instantiateItem(View collection, int position) {
        LayoutInflater inflater = (LayoutInflater) collection.getContext()
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        int resId = 0;
        switch (position) {
            case 0:
                resId = R.layout.field01;
                break;
            case 1:
                resId = R.layout.add_site;





                break;
            case 2:
                resId = R.layout.main;
                break;

        }

        View view = inflater.inflate(resId, null);
        ((ViewPager) collection).addView(view, 0);
        return view;
    }

    @Override
    public void destroyItem(View arg0, int arg1, Object arg2) {
        ((ViewPager) arg0).removeView((View) arg2);
    }
    @Override
    public boolean isViewFromObject(View arg0, Object arg1) {
        return arg0 == ((View) arg1);
    }
    @Override
    public Parcelable saveState() {
        return null;
    }


}

}

Any help is appreciated!

Answer 1

call :

 mPager.setCurrentItem(2);

in your onClick() method, or for a smoother scroll:

mPager.setCurrentItem(2, true); 

Answer 2

I can't really answer WHY exactly this happens, but if you delay the setCurrentItem call for a few milliseconds it should work. My guess is that because during onResume there hasn't been a rendering pass yet, and the ViewPager needs one or something like that.

private ViewPager viewPager;

@Override
public void onResume() {
    final int pos = 3;
    viewPager.postDelayed(new Runnable() {

        @Override
        public void run() {
            viewPager.setCurrentItem(pos);
        }
    }, 100);
}

Original Answer: here