How to use

getCurrentItem

method

in

androidx.viewpager.widget.ViewPager

@Override public int getCurrentItem() {
  return mAdapter != null ? mAdapter.toRealPosition(super.getCurrentItem()) : 0;
}

@Override
protected void onAttachedToWindow() {
  super.onAttachedToWindow();
  if (mViewPager != null) {
    scrollToTab(mViewPager.getCurrentItem(), 0);
  }
}

@Override
public boolean onKeyDown(int code, KeyEvent event) {
  if (code == KeyEvent.KEYCODE_ENTER || code == KeyEvent.KEYCODE_BUTTON_A ||
      code == KeyEvent.KEYCODE_DPAD_CENTER) {
    ViewPager vp = this.findViewById(R.id.view_pager);
    if (vp.getCurrentItem() == vp.getAdapter().getCount() - 1) {
      onDonePressed(fragments.get(vp.getCurrentItem()));
    } else {
      vp.setCurrentItem(vp.getCurrentItem() + 1);
    }
    return false;
  }
  return super.onKeyDown(code, event);
}

@Override
protected void onAttachedToWindow() {
  super.onAttachedToWindow();
  if (mViewPager != null) {
    scrollToTab(mViewPager.getCurrentItem(), 0);
  }
}

void toggleShowExtraKeys() {
  final ViewPager viewPager = findViewById(R.id.viewpager);
  final boolean showNow = mSettings.toggleShowExtraKeys(TermuxActivity.this);
  viewPager.setVisibility(showNow ? View.VISIBLE : View.GONE);
  if (showNow && viewPager.getCurrentItem() == 1) {
    // Focus the text input view if just revealed.
    findViewById(R.id.text_input).requestFocus();
  }
}

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());
  }
}

if (i == mViewPager.getCurrentItem()) {
  tabView.setSelected(true);

private void createIndicators() {
  removeAllViews();
  PagerAdapter adapter = mViewpager.getAdapter();
  int count;
  if (adapter == null || (count = adapter.getCount()) <= 0) {
    return;
  }
  createIndicators(count, mViewpager.getCurrentItem());
}

@Override
public void onRequestView(@NonNull ID id) {
  // Requesting ViewPager layout if it was in 'gone' state
  if (viewPager.getVisibility() == View.GONE) {
    viewPager.setVisibility(View.INVISIBLE);
  }
  // Trying to find view for currently shown page.
  // If it is not a selected page then we should scroll to it at first.
  int position = tracker.getPositionById(id);
  if (position == IntoTracker.NO_POSITION) {
    return; // Nothing we can do
  }
  if (viewPager.getCurrentItem() == position) {
    applyCurrentPage();
  } else {
    viewPager.setCurrentItem(position, false);
  }
}

  @Override public void onChanged() {
    super.onChanged();
    if (mViewpager == null) {
      return;
    }
    PagerAdapter adapter = mViewpager.getAdapter();
    int newCount = adapter != null ? adapter.getCount() : 0;
    int currentCount = getChildCount();
    if (newCount == currentCount) {
      // No change
      return;
    } else if (mLastPosition < newCount) {
      mLastPosition = mViewpager.getCurrentItem();
    } else {
      mLastPosition = -1;
    }
    createIndicators();
  }
};

@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);
  }
}

/**
 * Saves current screen state: whether we are in a full image mode or not, as well as current
 * grid position. So that we can restore UI on configuration change.
 */
private void saveScreenState() {
  clearScreenState();
  savedPhotoCount = gridAdapter.getCount();
  savedPagerPosition = listAnimator.isLeaving() || pagerAdapter.getCount() == 0
      ? NO_POSITION : views.pager.getCurrentItem();
  if (views.grid.getChildCount() > 0) {
    View child = views.grid.getChildAt(0);
    savedGridPosition = views.grid.getChildAdapterPosition(child);
    savedGridPositionFromTop = child.getTop()
        - Views.getMarginParams(child).topMargin
        - views.grid.getPaddingTop();
  }
}

private void applyCurrentPage() {
  final ID id = getAnimator().getRequestedId();
  if (id == null) {
    return;
  }
  if (viewPager.getAdapter() == null || viewPager.getAdapter().getCount() == 0) {
    return;
  }
  final int position = tracker.getPositionById(id);
  if (position == IntoTracker.NO_POSITION) {
    switchToCurrentPage();
    return;
  }
  if (position != viewPager.getCurrentItem()) {
    return;
  }
  final View view = tracker.getViewById(id); // View may be null
  if (view instanceof AnimatorView) {
    getAnimator().setToView(id, (AnimatorView) view);
  } else if (view != null) {
    throw new IllegalArgumentException("View for " + id + " should be AnimatorView");
  }
}

/**
 * Photos loading results callback.
 */
@Result(FlickrApi.LOAD_IMAGES_EVENT)
private void onPhotosLoaded(List<Photo> photos, boolean hasMore) {
  // RecyclerView will continue scrolling when new items are added, we need to stop it.
  // Seems like this buggy behavior was introduced in support library v26.0.x
  final boolean onBottom =
      views.grid.findViewHolderForAdapterPosition(gridAdapter.getCount() - 1) != null;
  if (onBottom) {
    views.grid.stopScroll();
  }
  // Setting new photos list
  gridAdapter.setPhotos(photos, hasMore);
  pagerAdapter.setPhotos(photos);
  gridAdapter.onNextItemsLoaded();
  // Ensure listener called for 0 position
  pagerListener.onPageSelected(views.pager.getCurrentItem());
  // Restoring saved state
  if (savedPagerPosition != NO_POSITION && savedPagerPosition < photos.size()) {
    pagerAdapter.setActivated(true);
    listAnimator.enter(savedPagerPosition, false);
  }
  if (savedGridPosition != NO_POSITION && savedGridPosition < photos.size()) {
    ((GridLayoutManager) views.grid.getLayoutManager())
        .scrollToPositionWithOffset(savedGridPosition, savedGridPositionFromTop);
  }
  clearScreenState();
}

private void switchToCurrentPage() {
  if (viewPager.getAdapter() == null || viewPager.getAdapter().getCount() == 0) {
    return;
  }
  final ID id = getAnimator().getRequestedId();
  final ID currentId = tracker.getIdByPosition(viewPager.getCurrentItem());
  // If user scrolled to new page we should silently switch views
  if (id != null && currentId != null && !id.equals(currentId)) {
    // Saving current state
    AnimatorView toView = getAnimator().getToView();
    ViewPositionAnimator toAnimator = toView == null ? null : toView.getPositionAnimator();
    boolean isLeaving = toAnimator != null && toAnimator.isLeaving();
    float position = toAnimator == null ? 0f : toAnimator.getPosition();
    boolean isAnimating = toAnimator != null && toAnimator.isAnimating();
    // Switching to new page, preventing exit of previous page
    skipExit();
    getAnimator().enter(currentId, false);
    // If exit animation was in place we should continue it
    if (isLeaving && position > 0f) {
      getAnimator().exit(isAnimating);
    }
  }
}

public void onPrepareOptionsMenu(Menu menu) {
  int pageNum = mViewPager.getCurrentItem();
  if (pageNum == 0) {
    menu.findItem(R.id.source_button).setVisible(true);
  } else {
    menu.findItem(R.id.source_button).setVisible(false);
  }
  getActivity().invalidateOptionsMenu();
}

public void onPrepareOptionsMenu(Menu menu) {
  int pageNum = mViewPager.getCurrentItem();
  if (pageNum == 0) {
    menu.findItem(R.id.duckConvertAttack).setVisible(true);
  } else {
    menu.findItem(R.id.duckConvertAttack).setVisible(false);
  }
  getActivity().invalidateOptionsMenu();
}

  @Override
  public void onBackPressed() {
    if (hasPreviousPage()) {
      mViewPager.setCurrentItem(mViewPager.getCurrentItem() - 1);
      return;
    }
    super.onBackPressed();
  }
}

@Override
public NdefRecord createNfcAppData() {
  if (adapter.getCount() == 0) {
    return null;
  }
  Event event = adapter.getEvent(pager.getCurrentItem());
  if (event == null) {
    return null;
  }
  return NfcUtils.createEventAppData(this, event);
}

@Override
protected void onActionSave() {
  if (mPaymentFlowPagerAdapter.getPageAt(
      mViewPager.getCurrentItem()).equals(PaymentFlowPagerEnum.SHIPPING_INFO)) {
    onShippingInfoSubmitted();
  } else {
    onShippingMethodSave();
  }
}