title: Viewpager setCurrentItem() doesn't update onPageSelected()
body: <p>When I swipe between questions, it loads current page number correctly</p>
  
  <p>BUT when I use next button,  first click doesnt loads pagenumber ( I mean <code>onPageSelected()</code> doesnt work.)  second and other clicks loads content but it loads 1 page previous.</p>
  
  <pre><code>@Override
  protected void onCreate(final Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
  
      this.setContentView(R.layout.activity_main);
  
      mPager = (ViewPager)findViewById(R.id.pager);
      QuestionPagerAdapter mAdapter = new QuestionPagerAdapter();
  
      mPager.setAdapter(mAdapter);
  
      OnPageChangeListener pageChangeListener = new OnPageChangeListener() {
  
          @Override
          public void onPageScrollStateChanged(int arg0) { }
  
          @Override
          public void onPageScrolled(int arg0, float arg1, int arg2) { }
  
          @Override
          public void onPageSelected(int position) {
              tv.setText( mPager.getCurrentItem()+"");
          }
  
      };
  
      mPager.setOnPageChangeListener(pageChangeListener);
  
      Question.next.setOnClickListener(new OnClickListener() {
  
          @Override
          public void onClick(View view) {
  
          mPager.setCurrentItem(getItem(+1));
          }
      }
  
      private int getItem(int i) {
          int a = mPager.getCurrentItem();
          i += a;
          return i;
      }
  });
  </code></pre>