DiscreteScrollView scrollView = findViewById(R.id.picker);
scrollView.setAdapter(new YourAdapterImplementation());

scrollView.setOrientation(DSVOrientation o); //Sets an orientation of the view
scrollView.setOffscreenItems(count); //Reserve extra space equal to (childSize * count) on each side of the view
scrollView.setOverScrollEnabled(enabled); //Can also be set using android:overScrollMode xml attribute

scrollView.getCurrentItem(); //returns adapter position of the currently selected item or -1 if adapter is empty.
scrollView.scrollToPosition(int position); //position becomes selected
scrollView.smoothScrollToPosition(int position); //position becomes selected with animated scroll
scrollView.setItemTransitionTimeMillis(int millis); //determines how much time it takes to change the item on fling, settle or smoothScroll

scrollView.setItemTransformer(transformer);

public interface DiscreteScrollItemTransformer {
    /**
     * In this method you apply any transform you can imagine (perfomance is not guaranteed).
     * @param position is a value inside the interval [-1f..1f]. In idle state:
     * |view1|  |currentlySelectedView|  |view2|
     * -view1 and everything to the left is on position -1;
     * -currentlySelectedView is on position 0;
     * -view2 and everything to the right is on position 1.
     */
    void transformItem(View item, float position); 
}

scrollView.setClampTransformProgressAfter(n);

cityPicker.setItemTransformer(new ScaleTransformer.Builder()
  .setMaxScale(1.05f) 
  .setMinScale(0.8f) 
  .setPivotX(Pivot.X.CENTER) // CENTER is a default one
  .setPivotY(Pivot.Y.BOTTOM) // CENTER is a default one
  .build());

scrollView.setSlideOnFling(true);

scrollView.setSlideOnFlingThreshold(value);

InfiniteScrollAdapter wrapper = InfiniteScrollAdapter.wrap(yourAdapter);
scrollView.setAdapter(wrapper);

int getRealItemCount();

int getRealCurrentPosition();

int getRealPosition(int position);

/*
 * You will probably want this method in the following use case:
 * int targetAdapterPosition = wrapper.getClosestPosition(targetPosition);
 * scrollView.smoothScrollTo(targetAdapterPosition);
 * To scroll the data set for the least required amount to reach targetPosition.
 */
int getClosestPosition(int position); 

scrollView.setScrollConfig(config);

scrollView.addScrollStateChangeListener(listener);
scrollView.removeScrollStateChangeListener(listener);

public interface ScrollStateChangeListener<T extends ViewHolder> {

  void onScrollStart(T currentItemHolder, int adapterPosition); //called when scroll is started, including programatically initiated scroll
  
  void onScrollEnd(T currentItemHolder, int adapterPosition); //called when scroll ends
  /**
   * Called when scroll is in progress. 
   * @param scrollPosition is a value inside the interval [-1f..1f], it corresponds to the position of currentlySelectedView.
   * In idle state:
   * |view1|  |currentlySelectedView|  |view2|
   * -view1 is on position -1;
   * -currentlySelectedView is on position 0;
   * -view2 is on position 1.
   * @param currentIndex - index of current view
   * @param newIndex - index of a view which is becoming the new current
   * @param currentHolder - ViewHolder of a current view
   * @param newCurrent - ViewHolder of a view which is becoming the new current
   */
  void onScroll(float scrollPosition, int currentIndex, int newIndex, @Nullable T currentHolder, @Nullable T newCurrentHolder); 
}

scrollView.addScrollListener(listener);
scrollView.removeScrollListener(listener);

public interface ScrollListener<T extends ViewHolder> {
  //The same as ScrollStateChangeListener, but for the cases when you are interested only in onScroll()
  void onScroll(float scrollPosition, int currentIndex, int newIndex, @Nullable T currentHolder, @Nullable T newCurrentHolder);
}

scrollView.addOnItemChangedListener(listener);
scrollView.removeOnItemChangedListener(listener);

public interface OnItemChangedListener<T extends ViewHolder> {
  /**
   * Called when new item is selected. It is similar to the onScrollEnd of ScrollStateChangeListener, except that it is 
   * also called when currently selected item appears on the screen for the first time.
   * viewHolder will be null, if data set becomes empty 
   */
  void onCurrentItemChanged(@Nullable T viewHolder, int adapterPosition); 
}