How to use

getSelections

method

in

com.mikepenz.fastadapter.FastAdapter

/**
 * get the current position of the selected drawer element
 *
 * @return
 */
public int getCurrentSelectedPosition() {
  return mDrawerBuilder.mAdapter.getSelections().size() == 0 ? -1 : mDrawerBuilder.mAdapter.getSelections().iterator().next();
}

  @Override
  public void onSelectionChanged(SimpleItem item, boolean selected) {
    Log.i("FastAdapter", "SelectedCount: " + mFastAdapter.getSelections().size() + " ItemsCount: " + mFastAdapter.getSelectedItems().size());
  }
});

  @Override
  public boolean onClick(View v, IAdapter<SimpleItem> adapter, @NonNull SimpleItem item, int position) {
    Toast.makeText(v.getContext(), "SelectedCount: " + mFastAdapter.getSelections().size() + " ItemsCount: " + mFastAdapter.getSelectedItems().size(), Toast.LENGTH_SHORT).show();
    return false;
  }
});

  @Override
  public void onClick(View v, int position, FastAdapter<RadioButtonSampleItem> fastAdapter, RadioButtonSampleItem item) {
    if (!item.isSelected()) {
      Set<Integer> selections = fastAdapter.getSelections();
      if (!selections.isEmpty()) {
        int selectedPosition = selections.iterator().next();
        fastAdapter.deselect();
        fastAdapter.notifyItemChanged(selectedPosition);
      }
      fastAdapter.select(position);
    }
  }
}

@Override
public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
  mUndoHelper.remove(findViewById(android.R.id.content), "Item removed", "Undo", Snackbar.LENGTH_LONG, mFastAdapter.getSelections());
  //as we no longer have a selection so the actionMode can be finished
  mode.finish();
  //we consume the event
  return true;
}

/**
 * helper method to get all selections from the ItemAdapter's original item list
 *
 * @return a Set with the global positions of all selected Items
 */
public Set<Integer> getSelections() {
  if (mOriginalItems != null) {
    Set<Integer> selections = new HashSet<>();
    int adapterOffset = mItemAdapter.getFastAdapter().getPreItemCountByOrder(mItemAdapter.getOrder());
    for (int i = 0, size = mOriginalItems.size(); i < size; i++) {
      Item item = mOriginalItems.get(i);
      if (item.isSelected()) {
        selections.add(i + adapterOffset);
      }
    }
    return selections;
  } else {
    return mItemAdapter.getFastAdapter().getSelections();
  }
}

@Test
public void select() throws Exception {
  adapter.withSelectable(true);
  itemAdapter.set(TestDataGenerator.genTestItemList(100));
  assertThat(adapter.getSelectedItems().size()).isEqualTo(0);
  assertThat(adapter.getSelections().size()).isEqualTo(0);
  adapter.select(10);
  assertThat(adapter.getSelectedItems().size()).isEqualTo(1);
  assertThat(adapter.getSelectedItems().iterator().next().getIdentifier()).isEqualTo(10);
  assertThat(adapter.getSelections().size()).isEqualTo(1);
  assertThat(adapter.getSelections().iterator().next()).isEqualTo(10);
}

case android.R.id.home:
  Toast.makeText(getApplicationContext(), "selections = " +
      fastAdapter.getSelections(), Toast.LENGTH_LONG).show();
  onBackPressed();
  return true;

int selection = mAdapter.getSelections().size() == 0 ? -1 : mAdapter.getSelections().iterator().next();
mOnDrawerItemClickListener.onItemClick(null, selection, getDrawerItem(selection));

  return true;
case R.id.item_change:
  for (Integer pos : (Iterable<Integer>) mFastAdapter.getSelections()) {
    ImageItem i = (ImageItem) mItemAdapter.getAdapterItem(pos);
    i.withName("CHANGED");