How to use

addOnPageChangeListener

method

in

androidx.viewpager.widget.ViewPager

  @Override
  public void onAddedToViewPager(ListenableTabLayout tl, ViewPager vp) {
    viewPager = vp;
    viewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener(){
      @Override
      public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        if(indicatorView != null && tabLayout != null && viewPager != null) {
          super.onPageScrolled(position, positionOffset, positionOffsetPixels);
          if (tabLayout.getTabCount() == 0) {
            return;
          }
          final View tabView = ((ViewGroup) tabLayout.getChildAt(0)).getChildAt(position);
          final int tabWidth = tabView.getWidth();
          float x = tabView.getLeft() + tabWidth * positionOffset;
          x += (tabWidth / 2f - indicatorView.getWidth() / 2f);
          indicatorView.setX(x);
        }
      }
    });
  }
};

private void init(Context context) {
  super.removeOnPageChangeListener(onPageChangeListener);
  super.addOnPageChangeListener(onPageChangeListener);
}

  /**
   * @deprecated User ViewPager addOnPageChangeListener
   */
  @Deprecated public void setOnPageChangeListener(
      ViewPager.OnPageChangeListener onPageChangeListener) {
    if (mViewpager == null) {
      throw new NullPointerException("can not find Viewpager , setViewPager first");
    }
    mViewpager.removeOnPageChangeListener(onPageChangeListener);
    mViewpager.addOnPageChangeListener(onPageChangeListener);
  }
}

/**
 * Sets the associated view pager. Note that the assumption here is that the pager content
 * (number of tabs and tab titles) does not change after this call has been made.
 */
public void setViewPager(ViewPager viewPager) {
  mTabStrip.removeAllViews();
  mViewPager = viewPager;
  if (viewPager != null) {
    viewPager.addOnPageChangeListener(new InternalViewPagerListener());
    populateTabStrip();
  }
}

/**
 * Sets the associated view pager. Note that the assumption here is that the pager content
 * (number of tabs and tab titles) does not change after this call has been made.
 */
public void setViewPager(ViewPager viewPager) {
  mTabStrip.removeAllViews();
  mViewPager = viewPager;
  if (viewPager != null) {
    viewPager.addOnPageChangeListener(new InternalViewPagerListener());
    populateTabStrip();
  }
}

public void setViewPager(@Nullable ViewPager viewPager) {
  mViewpager = viewPager;
  if (mViewpager != null && mViewpager.getAdapter() != null) {
    mLastPosition = -1;
    createIndicators();
    mViewpager.removeOnPageChangeListener(mInternalPageChangeListener);
    mViewpager.addOnPageChangeListener(mInternalPageChangeListener);
    mInternalPageChangeListener.onPageSelected(mViewpager.getCurrentItem());
  }
}

public IntoViewPagerListener(ViewPager viewPager, IntoTracker<ID> tracker) {
  this.viewPager = viewPager;
  this.tracker = tracker;
  viewPager.setVisibility(View.GONE); // We do not need to initialize ViewPager on startup
  viewPager.addOnPageChangeListener(new PagerListener());
  viewPager.setOnHierarchyChangeListener(new ChildStateListener());
}

viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
  @Override
  public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

@Override
public void setupWithViewPager(ViewPager viewPager) {
  if (viewPager == null) {
    return;
  }
  mViewPager = viewPager;
  if (mPageChangeListener != null) {
    mViewPager.removeOnPageChangeListener(mPageChangeListener);
  } else {
    mPageChangeListener = new ViewPagerPageChangeListener();
  }
  if (mNavigationController != null) {
    int n = mViewPager.getCurrentItem();
    if (mNavigationController.getSelected() != n) {
      mNavigationController.setSelect(n);
    }
    mViewPager.addOnPageChangeListener(mPageChangeListener);
  }
}

/**
 * Initializing pager and fullscreen mode.
 */
private void initPager() {
  // Setting up pager adapter
  pagerAdapter = new PhotoPagerAdapter(views.pager, getSettingsController());
  pagerListener = new ViewPager.SimpleOnPageChangeListener() {
    @Override
    public void onPageSelected(int position) {
      onPhotoInPagerSelected(position);
    }
  };
  views.pager.setAdapter(pagerAdapter);
  views.pager.addOnPageChangeListener(pagerListener);
  views.pager.setPageTransformer(true, new DepthPageTransformer());
  // Setting up pager toolbar
  views.pagerToolbar.setNavigationIcon(R.drawable.ic_arrow_back_white_24dp);
  views.pagerToolbar.setNavigationOnClickListener(view -> onBackPressed());
  // Enabling immersive mode by clicking on full screen image
  pagerAdapter.setImageClickListener(() -> {
    if (!listAnimator.isLeaving()) {
      // Toggle immersive mode
      showSystemUi(!isSystemUiShown());
    }
  });
  getWindow().getDecorView().setOnSystemUiVisibilityChangeListener(
      visibility -> views.pagerToolbar.animate().alpha(isSystemUiShown() ? 1f : 0f));
}

mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
  @Override
  public void onPageScrolled(final int position, final float v, final int i2) { /* do nothing */ }

viewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
  @Override
  public void onPageSelected(int position) {

viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
  @Override

@Override
public void setViewPager(ViewPager view) {
  if (mViewPager == view) {
    return;
  }
  if (mViewPager != null) {
    mViewPager.removeOnPageChangeListener(this);
  }
  if (view.getAdapter() == null) {
    throw new IllegalStateException("ViewPager does not have adapter instance.");
  }
  mViewPager = view;
  mViewPager.addOnPageChangeListener(this);
  invalidate();
}

/**
 * You must call this AFTER setting the Adapter for the ViewPager, or it won't display the right amount of points.
 *
 * @param viewPager
 */
public void setViewPager(ViewPager viewPager) {
  this.viewPager = viewPager;
  viewPager.addOnPageChangeListener(this);
  size = viewPager.getAdapter().getCount();
  invalidate();
}

protected void setupWithViewPager(@NonNull TabLayout tabLayout, @NonNull ViewPager viewPager) {
  final PagerAdapter adapter = viewPager.getAdapter();
  if (adapter == null) {
    throw new IllegalArgumentException("ViewPager does not have a PagerAdapter set");
  }
  setTabsFromPagerAdapter(tabLayout, adapter, viewPager.getCurrentItem());
  viewPager.getAdapter().registerDataSetObserver(mInternalDataSetObserver);
  viewPager.addOnPageChangeListener(mInternalTabLayoutOnPageChangeListener);
  viewPager.addOnAdapterChangeListener(mInternalOnAdapterChangeListener);
  tabLayout.addOnTabSelectedListener(mInternalOnTabSelectedListener);
}

private void onAttachedToViewPager(@NonNull ViewPager pager) {
  if (mView instanceof TabStripView)
    ((TabStripView) mView).onAttachedToViewPager(pager);
  else if (mView instanceof TabStripViewGroup)
    ((TabStripViewGroup) mView).onAttachedToViewPager(pager);
  pager.addOnPageChangeListener(this);
  pager.addOnAdapterChangeListener(this);
  onViewPagerAdapterChanged(null, pager.getAdapter());
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
  cleanCmd();
  View rootView = inflater.inflate(R.layout.mitmf, container, false);
  tabsPagerAdapter = new TabsPagerAdapter(getActivity().getSupportFragmentManager());
  ViewPager mViewPager = (ViewPager) rootView.findViewById(R.id.pagerMITMF);
  mViewPager.setAdapter(tabsPagerAdapter);
  nh = new NhPaths();
  mViewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
    @Override
    public void onPageSelected(int position) {
      getActivity().invalidateOptionsMenu();
    }
  });
  setHasOptionsMenu(true);
  return rootView;
}

public void setViewPager(ViewPager viewPager) {
  this.viewPager = viewPager;
  viewPager.addOnPageChangeListener(this);
  setPageCount(viewPager.getAdapter().getCount());
  viewPager.getAdapter().registerDataSetObserver(new DataSetObserver() {
    @Override
    public void onChanged() {
      setPageCount(DynamicPageIndicator.this.viewPager.getAdapter().getCount());
    }
  });
  setCurrentPageImmediate();
}

public BuildLayout(Context context, Star star, List<Colony> colonies, int initialIndex) {
 super(context);
 this.star = star;
 this.colonies = colonies;
 inflate(context, R.layout.build, this);
 colonyPagerAdapter = new ColonyPagerAdapter(context, star, colonies, this);
 viewPager = findViewById(R.id.pager);
 viewPager.setAdapter(colonyPagerAdapter);
 viewPager.setCurrentItem(initialIndex);
 planetIcon = findViewById(R.id.planet_icon);
 planetName = findViewById(R.id.planet_name);
 buildQueueDescription = findViewById(R.id.build_queue_description);
 bottomPane = findViewById(R.id.bottom_pane);
 viewPager.addOnPageChangeListener(pageChangeListener);
}