Develop Reference

How to save scroll state of a Recyclerview when an item is clicked?

I have an issue with Recyclerview item selection , which is set up in a fragment , the problem is each page which is created by ViewVager has its own instance of the Recyclerview so the output is that selecting Recyclerview items will reset the scroll state of the Recyclerview, so I'm looking for a solution to to save scroll state of a Recyclerview when an item is clicked.
Fragment onViewCreated
// setting RecyclerView
mEpisodesList = (CustomRecyclerView) view.findViewById(R.id.episodesLIST);
// getting episodeslist
ArrayList<PlanetModel> episodeslist = new ArrayList<>();
for (TvShowEpisode e : mEpisodes) {
episodeslist.add(new PlanetModel(e.mEpisode));
}
// Setting LinearLayoutManager
LinearLayoutManager layoutManager
= new LinearLayoutManager(mContext.getApplicationContext(), LinearLayoutManager.HORIZONTAL, false);
//mEpisodesList.setLayoutManager(new LinearLayoutManager(mContext));
mEpisodesList.setLayoutManager(layoutManager);
// Setting RecyclerView Adapter
int currentPosition = getArguments().getInt("position");
planetAdapter = new PlanetAdapter(episodeslist, currentPosition, new PlanetAdapter.OnItemClickListener() {
#Override
public void onItemClick(final int pos) {
int scrollValue = mEpisodesList.getHorizontalScrollOffset();
mCallback.sendText(pos, scrollValue);
}
});
mEpisodesList.setAdapter(planetAdapter);
int scrollValue = getArguments().getInt("scrollValue");
new Handler().postDelayed(() -> mEpisodesList.scrollBy(scrollValue, 0), 100);
activity
public class TvShowEpisodeDetails extends MizActivity implements TvShowEpisodeDetailsFragment.TextClicked {
#Override
protected int getLayoutResource() {
return R.layout.viewpager_with_toolbar_overlay;
}
#Override
public void onCreate(Bundle savedInstanceState) {
mBus = MizuuApplication.getBus();
super.onCreate(savedInstanceState);
// Set theme
setTheme(R.style.Mizuu_Theme_NoBackground);
ViewUtils.setupWindowFlagsForStatusbarOverlay(getWindow(), true);
ViewUtils.setProperToolbarSize(this, mToolbar);
mShowId = getIntent().getExtras().getString(SHOW_ID);
mSeason = getIntent().getExtras().getInt("season");
mEpisode = getIntent().getExtras().getInt("episode");
mDatabaseHelper = MizuuApplication.getTvEpisodeDbAdapter();
Cursor cursor = mDatabaseHelper.getEpisodes(mShowId);
try {
while (cursor.moveToNext()) {
mEpisodes.add(new TvShowEpisode(this, mShowId,
cursor.getString(cursor.getColumnIndex(DbAdapterTvShowEpisodes.KEY_EPISODE_TITLE)),
cursor.getString(cursor.getColumnIndex(DbAdapterTvShowEpisodes.KEY_EPISODE_PLOT)),
cursor.getString(cursor.getColumnIndex(DbAdapterTvShowEpisodes.KEY_SEASON)),
cursor.getString(cursor.getColumnIndex(DbAdapterTvShowEpisodes.KEY_EPISODE)),
cursor.getString(cursor.getColumnIndex(DbAdapterTvShowEpisodes.KEY_EPISODE_AIRDATE)),
cursor.getString(cursor.getColumnIndex(DbAdapterTvShowEpisodes.KEY_EPISODE_DIRECTOR)),
cursor.getString(cursor.getColumnIndex(DbAdapterTvShowEpisodes.KEY_EPISODE_WRITER)),
cursor.getString(cursor.getColumnIndex(DbAdapterTvShowEpisodes.KEY_EPISODE_GUESTSTARS)),
cursor.getString(cursor.getColumnIndex(DbAdapterTvShowEpisodes.KEY_EPISODE_RATING)),
cursor.getString(cursor.getColumnIndex(DbAdapterTvShowEpisodes.KEY_HAS_WATCHED)),
cursor.getString(cursor.getColumnIndex(DbAdapterTvShowEpisodes.KEY_FAVOURITE))
));
}
} catch (Exception e) {
} finally {
cursor.close();
}
final ArrayList<PlanetModel> episodeslist = new ArrayList<>();
for (TvShowEpisode e : mEpisodes) {
episodeslist.add(new PlanetModel(e.mEpisode));
}
mShowTitle = MizuuApplication.getTvDbAdapter().getShowTitle(mShowId);
setTitle(mShowTitle);
mViewPager = (ViewPager) findViewById(R.id.awesomepager);
mViewPager.setAdapter(new TvShowEpisodeDetailsAdapter(getSupportFragmentManager()));
for (int i = 0; i < mEpisodes.size(); i++)
fragments.add(TvShowEpisodeDetailsFragment
.newInstance(mShowId, Integer.parseInt(mEpisodes.get(i).getSeason()), Integer.parseInt(mEpisodes.get(i).getEpisode()), i, mScrollValue));
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
for (int i = 0; i < episodeslist.size(); i++) {
episodeslist.get(i).setPlanetSelected(false);
}
episodeslist.get(position).setPlanetSelected(true);
//notify your recycler views adaper
ViewUtils.updateToolbarBackground(TvShowEpisodeDetails.this, mToolbar, 0, mEpisodes.get(position).getTitle(), Color.TRANSPARENT);
}
});
if (savedInstanceState != null) {
mViewPager.setCurrentItem(savedInstanceState.getInt("tab", 0));
} else {
for (int i = 0; i < mEpisodes.size(); i++) {
if (mEpisodes.get(i).getSeason().equals(MizLib.addIndexZero(mSeason)) && mEpisodes.get(i).getEpisode().equals(MizLib.addIndexZero(mEpisode))) {
mViewPager.setCurrentItem(i);
SharedPreferences setPref = this.getSharedPreferences("TvShowEpisodeDetails", Context.MODE_PRIVATE);
setPref.edit().putInt("i", i).apply();
break;
}
}
}
}
private class TvShowEpisodeDetailsAdapter extends FragmentPagerAdapter {
public TvShowEpisodeDetailsAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int index) {
// return TvShowEpisodeDetailsFragment.newInstance(mShowId, Integer.parseInt(mEpisodes.get(index).getSeason()), Integer.parseInt(mEpisodes.get(index).getEpisode()));
return fragments.get(index);
}
#Override
public int getCount() {
return mEpisodes.size();
}
}
Recyclerview adapter
public class PlanetAdapter extends RecyclerView.Adapter<PlanetAdapter.PlanetViewHolder> {
public interface OnItemClickListener {
void onItemClick(int item);
}
private final ArrayList<PlanetModel> episodeslist;
private final OnItemClickListener listener;
SharedPreferences getPref = getContext().getSharedPreferences("TvShowEpisodeDetails", Context.MODE_PRIVATE);
int pos = getPref.getInt("i", 0);
int isPlanetSelected = pos;
private final int highlightedPos;
public PlanetAdapter(ArrayList<PlanetModel> episodeslist, int highlightedPosition, OnItemClickListener listener) {
this.episodeslist = episodeslist;
this.listener = listener;
this.highlightedPos = highlightedPosition;
}
#NonNull
#Override
public PlanetAdapter.PlanetViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.planet_row, parent, false);
return new PlanetViewHolder(v);
}
#Override
public void onBindViewHolder(PlanetAdapter.PlanetViewHolder vh, final int position) {
TextView tv = (TextView) vh.itemView;
PlanetModel planetModel = episodeslist.get(position);
tv.setText(planetModel.getPlanetName());
tv.setCompoundDrawablesWithIntrinsicBounds(R.drawable.bg, 0, 0, 0);
if (highlightedPos == position) {
vh.itemView.setBackgroundColor(getContext().getResources().getColor(R.color.colorPrimaryLight));
} else {
vh.itemView.setBackgroundColor(getContext().getResources().getColor(R.color.colorPrimaryDark));
}
//holder.image.setImageResource(R.drawable.planetimage);
//vh.text.setText(episodeslist.get(position).toString());
}
#Override
public int getItemCount() {
return episodeslist.size();
}
public class PlanetViewHolder extends RecyclerView.ViewHolder {
protected TextView text;
public PlanetViewHolder(View itemView) {
super(itemView);
text = (TextView) itemView.findViewById(R.id.text_id);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Log.d("LOG_TAG", "onClick: current item: " + highlightedPos);
final int previousItem = isPlanetSelected;
isPlanetSelected = getPosition();
SharedPreferences setPref = v.getContext().getSharedPreferences("PlanetAdapter", Context.MODE_PRIVATE);
setPref.edit().putInt("newPosition", getPosition()).apply();
listener.onItemClick(getPosition());
}
});
}
// public void bind(final PlanetModel item, final OnItemClickListener listener) {
// }
}

You can solve this by tracking the current scroll value of the RecyclerView, and whenever you hit an a ReyclerView item; add a new parameter to the listener callback with this tracked scroll value to update the new fragment that will be shown on the ViewPager.
Track the scroll value:
mEpisodesList.setOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
scrollValue += dx;
}
});
Pass it as interface callback:
planetAdapter = new PlanetAdapter(episodeslist, currentPosition, new PlanetAdapter.OnItemClickListener() {
#Override
public void onItemClick(final int pos) {
mCallback.sendText(pos, scrollValue);
}
});
And update that in the list of ViewPager fragments before scrolling to the new page:
#Override
public void sendText(int position, int scrollValue) {
mScrollValue = scrollValue;
TvShowEpisodeDetailsFragment frag = fragments.get(position);
Bundle arguments = frag.getArguments();
arguments.putInt("scrollValue", scrollValue);
mViewPager.setCurrentItem(position, false);
}

try this
// save
recyclerViewState = binding.mainList.layoutManager?.onSaveInstanceState()
// restore
recyclerViewState?.let {
binding.mainList.layoutManager?.onRestoreInstanceState(it)
}

SnapHelper Item Position

I'm using vertical RecyclerView to list my items and SnapHelper to snap center item. The idea is to randomize selection, so user swipe screen or shake the device and it is scrolling to random position.
Number of items is 20, however I use Integer.MAX_VALUE for the number of elements in RecyclerView and initialize RecyclerView with position Integer.MAX_VALUE / 2 to create some kind of endless list.
To scroll to random position on device shake I need to know current snapped item position.
Is there any way to do it?
Here is my Fragment code:
public class PlaceListFragment extends Fragment {
private static final String TAG = "PlaceListFragment";
public static final String ARG_KEY1 = "key1";
private ArrayList<PlaceItem> places;
private RecyclerView recyclerView;
private SensorManager sensorManager;
private float accelValue;
private float accelLast;
private float shake;
SnapHelper snapHelper;
Vibrator vibe;
public static PlaceListFragment newInstance() {
Bundle args = new Bundle();
PlaceListFragment fragment = new PlaceListFragment();
fragment.setArguments(args);
return fragment;
}
public static PlaceListFragment newInstance(ArrayList<PlaceItem> places) {
Bundle args = new Bundle();
args.putParcelableArrayList(PlaceListActivity.KEY_PLACES, places);
PlaceListFragment fragment = new PlaceListFragment();
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
Log.d(TAG, "onCreate()");
super.onCreate(savedInstanceState);
places = getArguments().getParcelableArrayList(PlaceListActivity.KEY_PLACES);
accelValue = SensorManager.GRAVITY_EARTH;
accelLast = SensorManager.GRAVITY_EARTH;
shake = 0.00f;
vibe = (Vibrator) getActivity().getSystemService(Context.VIBRATOR_SERVICE);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_place_list, container, false);
recyclerView = (RecyclerView) v.findViewById(R.id.place_list);
snapHelper = new LinearSnapHelper();
snapHelper.attachToRecyclerView(recyclerView);
recyclerView.setOnFlingListener(snapHelper);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
recyclerView.setAdapter(new PlaceListAdapter(getActivity(), places));
recyclerView.scrollToPosition(PlaceListAdapter.MIDDLE);
sensorManager = (SensorManager) getActivity().getSystemService(Context.SENSOR_SERVICE);
sensorManager.registerListener(sensorListener, sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),SensorManager.SENSOR_DELAY_NORMAL);
return v;
}
#Override
public void onResume() {
super.onResume();
}
#Override
public void onPause() {
super.onPause();
}
private final SensorEventListener sensorListener = new SensorEventListener() {
#Override
public void onSensorChanged(SensorEvent event) {
float x = event.values[0];
float y = event.values[1];
float z = event.values[2];
accelLast = accelValue;
accelValue = (float) Math.sqrt((double) (x*x + y*y + z*z));
float delta = accelValue - accelLast;
shake = shake * 0.9f + delta;
if (shake > 12) {
vibe.vibrate(200);
}
}
#Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
};
}
And here is adapter:
public class PlaceListAdapter extends RecyclerView.Adapter<PlaceListAdapter.PlaceAdapterHolder> {
private final FragmentActivity context;
public static final int HALF_MAX_VALUE = Integer.MAX_VALUE/2;
public static int MIDDLE;
private List<PlaceItem> placeItems;
public static class PlaceAdapterHolder extends RecyclerView.ViewHolder {
private ImageView image;
private TextView textMain;
private TextView textRating;
public PlaceAdapterHolder(View itemView) {
super(itemView);
image = (ImageView) itemView.findViewById(R.id.icon);
textMain = (TextView) itemView.findViewById(R.id.txt_main_line);
textRating = (TextView) itemView.findViewById(R.id.txt_right_field);
}
public void bindPlace(PlaceItem placeItem) {
String placeName = placeItem.getName() == null? "?":placeItem.getName();
String firstLetter = placeName.substring(0, 1);
ColorGenerator generator = ColorGenerator.MATERIAL; // or use DEFAULT
int color = generator.getColor(placeName);
TextDrawable drawable = TextDrawable.builder()
.beginConfig()
.toUpperCase()
.endConfig()
.buildRect(firstLetter, color);
image.setImageDrawable(drawable);
textMain.setText(placeItem.getName());
textRating.setText(placeItem.getRating());
}
}
public PlaceListAdapter(FragmentActivity context, List<PlaceItem> placeItems) {
this.context = context;
this.placeItems = placeItems;
MIDDLE = HALF_MAX_VALUE - HALF_MAX_VALUE % placeItems.size();
}
#Override
public PlaceListAdapter.PlaceAdapterHolder onCreateViewHolder(ViewGroup parent, int viewType) {
final View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.place_list_one_line_item, parent, false);
return new PlaceAdapterHolder(view);
}
#Override
public int getItemCount() {
return Integer.MAX_VALUE;
}
#Override
public void onBindViewHolder(PlaceListAdapter.PlaceAdapterHolder holder, final int position) {
final PlaceItem placeItem = getItem(position);
holder.bindPlace(placeItem);
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
FragmentManager fm = context.getSupportFragmentManager();
PlaceDetailsFragment dialog = PlaceDetailsFragment.newInstance(getItem(position));
dialog.show(fm, "DETAILS_DIALOG");
}
});
}
private PlaceItem getItem(int position)
{
return placeItems.get(position % placeItems.size());
}
}

I used this on a project that had a RecyclerView with SnapHelper, not sure if it is what you want.
mRecyclerView.setHasFixedSize(true);
// use a linear layout manager
mLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
mRecyclerView.setLayoutManager(mLayoutManager);
// specify an adapter (see also next example)
mAdapter = new DemoSlidesAdapter(getApplicationContext());
mRecyclerView.setAdapter(mAdapter);
final SnapHelper snapHelper = new LinearSnapHelper();
snapHelper.attachToRecyclerView(mRecyclerView);
mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
if(newState == RecyclerView.SCROLL_STATE_IDLE) {
View centerView = snapHelper.findSnapView(mLayoutManager);
int pos = mLayoutManager.getPosition(centerView);
Log.e("Snapped Item Position:",""+pos);
}
}
});

I try to use this code with a PagerSnapHelper to mimic the pager behaviour and it was useful but i found some corner cases to solve, if you move fast from the last page to the first one and keep swapping until see the boundarie then the IDLE state doesnt happen and you lose your index. to solve that I move out the position from the IF and add a extra condition for this corner case.
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
super.onScrollStateChanged(recyclerView, newState)
val centerView = snapHelper.findSnapView(mLayoutManager)
val pos = mLayoutManager.getPosition(centerView!!)
if (newState == RecyclerView.SCROLL_STATE_IDLE || (pos == 0 && newState == RecyclerView.SCROLL_STATE_DRAGGING)) {
Log.d("BINDING", "positionView SCROLL_STATE_IDLE: $pos")
}
}
Code is in kotlin hope it helps

private fun recyclerViewScrollListener() = object: RecyclerView.OnScrollListener() {
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
super.onScrollStateChanged(recyclerView, newState)
if (newState == RecyclerView.SCROLL_STATE_IDLE) {
// layoutManager is LinearLayoutManager
val pos = layoutManager.findFirstCompletelyVisibleItemPosition()
Log.e(TAG, "onScrollStateChanged: $pos")
}
}
}
recyclerView.setOnScrollListener(recyclerViewScrollListener())

recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener(){
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
....
}
})

Saving Card Position in Adapter

I’m trying to pass the position of the card to SlideView Activity where onMenuItemClick was used to bring up the correct information about that specific card. Currently, I’m using getAdapterPosition in onMenuItemClick within my Adapter, but thats resulting in the last element drawn to screen being saved to my adapterPosition. I understand why it’s giving the last position, but unsure how to set the correct position. Should I try to save and pass the position via showPopupMenu or something else entirely? Below are my Adapter & MainActivity.
Adapter:
public class Adapter extends RecyclerView.Adapter<Adapter.MyViewHolder> {
private Context mContext;
private List<Properties> dogList;
private MyViewHolder holder;
public class MyViewHolder extends RecyclerView.ViewHolder {
public TextView title, count;
public ImageView thumbnail, overflow;
public MyViewHolder(View view) {
super(view);
title = (TextView) view.findViewById(R.id.title);
count = (TextView) view.findViewById(R.id.count);
thumbnail = (ImageView) view.findViewById(R.id.thumbnail);
overflow = (ImageView) view.findViewById(R.id.overflow);
}
}
public Adapter(Context mContext, List<Properties> dogList) {
this.mContext = mContext;
this.dogList = dogList;
}
#Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.card, parent, false);
return new MyViewHolder(itemView);
}
#Override
public void onBindViewHolder(final MyViewHolder holder, int position) {
this.holder=holder;
Properties dog = dogList.get(position);
holder.title.setText(dog.getName());
// loading dog cover using Glide library
Glide.with(mContext).load(dog.getThumbnail()).into(holder.thumbnail);
holder.overflow.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
showPopupMenu(holder.overflow);
}
});
}
/**
* Showing popup menu when tapping on icon
*/
private void showPopupMenu(View view) {
// inflate menu
PopupMenu popup = new PopupMenu(mContext, view);
MenuInflater inflater = popup.getMenuInflater();
inflater.inflate(R.menu.menu, popup.getMenu());
popup.setOnMenuItemClickListener(new MyMenuItemClickListener());
popup.show();
}
/**
* Click listener for popup menu items
*/
class MyMenuItemClickListener implements PopupMenu.OnMenuItemClickListener {
public MyMenuItemClickListener() {
}
#Override
public boolean onMenuItemClick(MenuItem menuItem) {
switch (menuItem.getItemId()) {
case R.id.action_add_favourite:
Toast.makeText(mContext, "Add to favourite", Toast.LENGTH_SHORT).show();
return true;
case R.id.action_more_info:
Intent slideStart = new Intent(mContext, SlideViewActivity.class);
super.getClass();
int adapterPosition = holder.getAdapterPosition();
slideStart.putExtra("position", adapterPosition);
slideStart.putExtra("list", (Serializable) dogList);
mContext.startActivity(slideStart);
return true;
default:
}
return false;
}
}
#Override
public int getItemCount() {
return dogList.size();
}
}
MainActivity:
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private RecyclerView recyclerView;
private Adapter adapter;
private List<Properties> dogList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
initCollapsingToolbar();
recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
dogList = new ArrayList<>();
adapter = new Adapter(this, dogList);
RecyclerView.LayoutManager mLayoutManager = new GridLayoutManager(this, 2);
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.addItemDecoration(new GridSpacingItemDecoration(2, dpToPx(10), true));
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(adapter);
prepareCards();
try {
Glide.with(this).load(R.drawable.austrailian_shepherd).into((ImageView) findViewById(R.id.backdrop));
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* Initializing collapsing toolbar
* Will show and hide the toolbar title on scroll
*/
private void initCollapsingToolbar() {
final CollapsingToolbarLayout collapsingToolbar =
(CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar);
collapsingToolbar.setTitle(" ");
AppBarLayout appBarLayout = (AppBarLayout) findViewById(R.id.appbar);
appBarLayout.setExpanded(true);
// hiding & showing the title when toolbar expanded & collapsed
appBarLayout.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
boolean isShow = false;
int scrollRange = -1;
#Override
public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
if (scrollRange == -1) {
scrollRange = appBarLayout.getTotalScrollRange();
}
if (scrollRange + verticalOffset == 0) {
collapsingToolbar.setTitle(getString(R.string.app_name));
isShow = true;
} else if (isShow) {
collapsingToolbar.setTitle(" ");
isShow = false;
}
}
});
}
private void prepareCards() {
int librarySize = getResources().getStringArray(R.array.titles).length;
for(int i=0;i<librarySize;i++) {
String dognames = getResources().getStringArray(R.array.titles)[i];
String doginfo = getResources().getStringArray(R.array.info)[i];
int imageId = getResources().getIdentifier(dognames.toLowerCase(Locale.getDefault()), "drawable", this.getPackageName());
Properties a = new Properties(dognames, doginfo, imageId);
dogList.add(a);
}
adapter.notifyDataSetChanged();
}
#Override
public void onClick(View v) {
}
/**
* RecyclerView item decoration - give equal margin around grid item
*/
public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {
private int spanCount;
private int spacing;
private boolean includeEdge;
public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge) {
this.spanCount = spanCount;
this.spacing = spacing;
this.includeEdge = includeEdge;
}
#Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
int position = parent.getChildAdapterPosition(view); // item position
int column = position % spanCount; // item column
if (includeEdge) {
outRect.left = spacing - column * spacing / spanCount; // spacing - column * ((1f / spanCount) * spacing)
outRect.right = (column + 1) * spacing / spanCount; // (column + 1) * ((1f / spanCount) * spacing)
if (position < spanCount) { // top edge
outRect.top = spacing;
}
outRect.bottom = spacing; // item bottom
} else {
outRect.left = column * spacing / spanCount; // column * ((1f / spanCount) * spacing)
outRect.right = spacing - (column + 1) * spacing / spanCount; // spacing - (column + 1) * ((1f / spanCount) * spacing)
if (position >= spanCount) {
outRect.top = spacing; // item top
}
}
}
}
/**
* Converting dp to pixel
*/
private int dpToPx(int dp) {
Resources r = getResources();
return Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, r.getDisplayMetrics()));
}
}

Try these modifications :
holder.overflow.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
showPopupMenu(holder.overflow, position);
}
});
private void showPopupMenu(View view, int pos) {
// inflate menu
PopupMenu popup = new PopupMenu(mContext, view);
MenuInflater inflater = popup.getMenuInflater();
inflater.inflate(R.menu.menu, popup.getMenu());
popup.setOnMenuItemClickListener(new MyMenuItemClickListener(pos));
popup.show();
}
class MyMenuItemClickListener implements PopupMenu.OnMenuItemClickListener {
int pos;
public MyMenuItemClickListener(int pos) {
this.pos = pos;
}
#Override
public boolean onMenuItemClick(MenuItem menuItem) {
switch (menuItem.getItemId()) {
case R.id.action_add_favourite:
Toast.makeText(mContext, "Add to favourite", Toast.LENGTH_SHORT).show();
return true;
case R.id.action_more_info:
Intent slideStart = new Intent(mContext, SlideViewActivity.class);
super.getClass();
slideStart.putExtra("position", pos);
slideStart.putExtra("list", (Serializable) dogList);
mContext.startActivity(slideStart);
return true;
default:
}
return false;
}
}

Get NullPointerException in LinearLayoutManager

I get this error:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference
Here is the RecyclerFragment:
public class ThreeFragment extends Fragment{
private TextView tvEmptyView;
private RecyclerView mRecyclerView;
private DataAdapter mAdapter;
private LinearLayoutManager mLayoutManager;
private List<Student> studentList;
protected Handler handler;
public ThreeFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootview = inflater.inflate(R.layout.fragment_one, container, false);
tvEmptyView = (TextView) rootview.findViewById(R.id.empty_view);
mRecyclerView = (RecyclerView) rootview.findViewById(R.id.my_recycler_view);
studentList = new ArrayList<Student>();
handler = new Handler();
loadData();
// use this setting to improve performance if you know that changes
// in content do not change the layout size of the RecyclerView
mRecyclerView.setHasFixedSize(true);
mLayoutManager = new LinearLayoutManager(getActivity());
mLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
// use a linear layout manager
mRecyclerView.setLayoutManager(mLayoutManager);
// create an Object for Adapter
mAdapter = new DataAdapter(studentList, mRecyclerView);
// set the adapter object to the Recyclerview
mRecyclerView.setAdapter(mAdapter);
// mAdapter.notifyDataSetChanged();
if (studentList.isEmpty()) {
mRecyclerView.setVisibility(View.GONE);
tvEmptyView.setVisibility(View.VISIBLE);
} else {
mRecyclerView.setVisibility(View.VISIBLE);
tvEmptyView.setVisibility(View.GONE);
}
mAdapter.setOnLoadMoreListener(new OnLoadMoreListener() {
#Override
public void onLoadMore() {
//add null , so the adapter will check view_type and show progress bar at bottom
studentList.add(null);
mAdapter.notifyItemInserted(studentList.size() - 1);
handler.postDelayed(new Runnable() {
#Override
public void run() {
// remove progress item
studentList.remove(studentList.size() - 1);
mAdapter.notifyItemRemoved(studentList.size());
//add items one by one
int start = studentList.size();
int end = start + 20;
for (int i = start + 1; i <= end; i++) {
studentList.add(new Student("Student " + i, "AndroidStudent" + i + "#gmail.com"));
mAdapter.notifyItemInserted(studentList.size());
}
mAdapter.setLoaded();
//or you can add all at once but do not forget to call mAdapter.notifyDataSetChanged();
}
}, 2000);
}
});
return rootview;
}
// load initial data
private void loadData() {
for (int i = 1; i <= 20; i++) {
studentList.add(new Student("Student " + i, "androidstudent" + i + "#gmail.com"));
}
}
}
Here is the adapter:
public class DataAdapter extends RecyclerView.Adapter {
private final int VIEW_ITEM = 1;
private final int VIEW_PROG = 0;
private List<Student> studentList;
// The minimum amount of items to have below your current scroll position
// before loading more.
private int visibleThreshold = 5;
private int lastVisibleItem, totalItemCount;
private boolean loading;
private OnLoadMoreListener onLoadMoreListener;
public DataAdapter(List<Student> students, RecyclerView recyclerView) {
studentList = students;
if (recyclerView.getLayoutManager() instanceof LinearLayoutManager) {
final LinearLayoutManager mLayoutManager = (LinearLayoutManager) recyclerView
.getLayoutManager();
recyclerView
.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrolled(RecyclerView recyclerView,
int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
totalItemCount = mLayoutManager.getItemCount();
lastVisibleItem = mLayoutManager
.findLastVisibleItemPosition();
if (!loading
&& totalItemCount <= (lastVisibleItem + visibleThreshold)) {
// End has been reached
// Do something
if (onLoadMoreListener != null) {
onLoadMoreListener.onLoadMore();
}
loading = true;
}
}
});
}
}
#Override
public int getItemViewType(int position) {
return studentList.get(position) != null ? VIEW_ITEM : VIEW_PROG;
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
RecyclerView.ViewHolder vh;
if (viewType == VIEW_ITEM) {
View v = LayoutInflater.from(parent.getContext()).inflate(
R.layout.list_row, parent, false);
vh = new StudentViewHolder(v);
} else {
View v = LayoutInflater.from(parent.getContext()).inflate(
R.layout.progress_item, parent, false);
vh = new ProgressViewHolder(v);
}
return vh;
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof StudentViewHolder) {
Student singleStudent = (Student) studentList.get(position);
((StudentViewHolder) holder).tvName.setText(singleStudent.getName());
((StudentViewHolder) holder).tvEmailId.setText(singleStudent.getEmailId());
((StudentViewHolder) holder).student = singleStudent;
} else {
((ProgressViewHolder) holder).progressBar.setIndeterminate(true);
}
}
public void setLoaded() {
loading = false;
}
#Override
public int getItemCount() {
return studentList.size();
}
public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
this.onLoadMoreListener = onLoadMoreListener;
}
//
public static class StudentViewHolder extends RecyclerView.ViewHolder {
public TextView tvName;
public TextView tvEmailId;
public Student student;
public StudentViewHolder(View v) {
super(v);
tvName = (TextView) v.findViewById(R.id.tvName);
tvEmailId = (TextView) v.findViewById(R.id.tvEmailId);
v.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(v.getContext(),
"OnClick :" + student.getName() + " \n " + student.getEmailId(),
Toast.LENGTH_SHORT).show();
}
});
}
}
public static class ProgressViewHolder extends RecyclerView.ViewHolder {
public ProgressBar progressBar;
public ProgressViewHolder(View v) {
super(v);
progressBar = (ProgressBar) v.findViewById(R.id.progressBar1);
}
}
}

Android simple tabs with toolbar

I've been struggling with tab implementation in my application and seen a lot of resources on the matter but nothing appears to be working for me. I just want 4 simple tabs with icons above my toolbar, that's all. Can someone help me out on achieving this?
Here's my code if needed:
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;
import java.util.ArrayList;
public class ProjectCreateScreen extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.secondary_layout1);
Toolbar toolbar = (Toolbar) findViewById(R.id.AwesomeBar);
setSupportActionBar(toolbar);
}
public void displayProjectOptions (View view) {
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_primary, menu);
return true;
}
final ArrayList<String> listItems=new ArrayList<String>();
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.addButton) {
final TextView noProject = (TextView) findViewById(R.id.NOPROJECT);
final ListAdapter addAdapter = new ArrayAdapter<String>(this,
R.layout.list_item, R.id.listFrame, listItems);
final ListView lv = (ListView) findViewById(R.id.lv);
lv.setAdapter(addAdapter);
noProject.setVisibility(View.GONE);
lv.setVisibility(View.VISIBLE);
listItems.add("New Project");
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Intent switchToEdit = new Intent(ProjectCreateScreen.this,
teamCreateScreen.class);
startActivity(switchToEdit);
}
});
}
return super.onOptionsItemSelected(item);
}
}
And xml file:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/rl">
<android.support.v7.widget.Toolbar
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?android:attr/actionBarSize"
android:id="#+id/AwesomeBar"
android:background="#color/custom_white">
</android.support.v7.widget.Toolbar>
<TextView
android:layout_width="200dp"
android:layout_height="wrap_content"
android:text="#string/noProjectsNotice"
android:id="#+id/NOPROJECT"
android:gravity="center"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true"
android:textSize="16sp"/>
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/AwesomeBar"
android:id="#+id/lv"
android:visibility="invisible">
</ListView>

If you are using toolbar you need to use SlidingTabLayout for tabs in toolbar as follows
TabFragment.java
public class TabFragment extends Fragment {
private SlidingTabLayout mSlidingTabLayout;
private MyActivityAdapter mAdapter;
private ViewPager mViewPager;
private Menu mMenu;
private ScreenNames mScreenName = ScreenNames.UNRAVELING_ME;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_swipe, container, false);
mSlidingTabLayout = (SlidingTabLayout) view.findViewById(R.id.sliding_tabs);
mSlidingTabLayout.setCustomTabView(R.layout.tab_indicator, android.R.id.text1);
mSlidingTabLayout.setSelectedIndicatorColors(getResources().getColor(R.color.unravel_secondary_red));
mSlidingTabLayout.setDistributeEvenly(true);
mSlidingTabLayout.setBackgroundColor(Color.parseColor("#F7F7F7"));
mSlidingTabLayout.setOnPageChangeListener(new ViewPager.OnPageChangeListener (){
#Override
public void onPageSelected(int position)
{
if(position == 0){
}
else {
}
}
#Override
public void onPageScrollStateChanged(int state)
{
}
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels)
{
}
});
mViewPager = (ViewPager) view.findViewById(R.id.pager);
mAdapter = new MyActivityAdapter(this, getChildFragmentManager());
mViewPager.setAdapter(mAdapter);
mSlidingTabLayout.setViewPager(mViewPager);
return view;
}
fragment_swipe.xml
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.unravel.widget.SlidingTabLayout
android:id="#+id/sliding_tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="0px"
android:layout_weight="1"/>
</LinearLayout>
MyActivityAdapter.java
public class MyActivityAdapter extends FragmentPagerAdapter {
private MyActivityFragment mFragment;
public MyActivityAdapter(MyActivityFragment fragment, FragmentManager fm) {
super(fm);
mFragment = fragment;
}
#Override
public Fragment getItem(int i) {
if (i == 0) {
return new fragment1();
}
else {
return new fragment2();
}
}
#Override
public int getCount() {
return 2;
}
#Override
public CharSequence getPageTitle(int position) {
if (position == 0) {
return "first tab";
} else {
return "second tab";
}
}
}
Fragment1.java
public class Fragment1 extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_fragment1, container, false);
}
}
Fragment2.java
public class Fragment2 extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_fragment1, container, false);
}
}
SlidingTabLayout.java
public class SlidingTabLayout extends HorizontalScrollView {
/**
* Allows COMPLETE control over the colors drawn in the tab layout. Set with
* {#link #setCustomTabColorizer(TabColorizer)}.
*/
public interface TabColorizer {
/**
* #return return the color of the indicator used when {#code position} is selected.
*/
int getIndicatorColor(int position);
}
private static final int TITLE_OFFSET_DIPS = 24;
private static final int TAB_VIEW_PADDING_DIPS = 16;
private static final int TAB_VIEW_TEXT_SIZE_SP = 18;
private int mTitleOffset;
private int mTabViewLayoutId;
private int mTabViewTextViewId;
private boolean mDistributeEvenly;
private ViewPager mViewPager;
private SparseArray<String> mContentDescriptions = new SparseArray<String>();
private ViewPager.OnPageChangeListener mViewPagerPageChangeListener;
private final SlidingTabStrip mTabStrip;
public SlidingTabLayout(Context context) {
this(context, null);
}
public SlidingTabLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public SlidingTabLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// Disable the Scroll Bar
setHorizontalScrollBarEnabled(false);
// Make sure that the Tab Strips fills this View
setFillViewport(true);
mTitleOffset = (int) (TITLE_OFFSET_DIPS * getResources().getDisplayMetrics().density);
mTabStrip = new SlidingTabStrip(context);
addView(mTabStrip, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
}
/**
* Set the custom {#link TabColorizer} to be used.
*
* If you only require simple custmisation then you can use
* {#link #setSelectedIndicatorColors(int...)} to achieve
* similar effects.
*/
public void setCustomTabColorizer(TabColorizer tabColorizer) {
mTabStrip.setCustomTabColorizer(tabColorizer);
}
public void setDistributeEvenly(boolean distributeEvenly) {
mDistributeEvenly = distributeEvenly;
}
/**
* Sets the colors to be used for indicating the selected tab. These colors are treated as a
* circular array. Providing one color will mean that all tabs are indicated with the same color.
*/
public void setSelectedIndicatorColors(int... colors) {
mTabStrip.setSelectedIndicatorColors(colors);
}
/**
* Set the {#link ViewPager.OnPageChangeListener}. When using {#link SlidingTabLayout} you are
* required to set any {#link ViewPager.OnPageChangeListener} through this method. This is so
* that the layout can update it's scroll position correctly.
*
* #see ViewPager#setOnPageChangeListener(ViewPager.OnPageChangeListener)
*/
public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) {
mViewPagerPageChangeListener = listener;
}
/**
* Set the custom layout to be inflated for the tab views.
*
* #param layoutResId Layout id to be inflated
* #param textViewId id of the {#link TextView} in the inflated view
*/
public void setCustomTabView(int layoutResId, int textViewId) {
mTabViewLayoutId = layoutResId;
mTabViewTextViewId = textViewId;
}
/**
* 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.setOnPageChangeListener(new InternalViewPagerListener());
populateTabStrip();
}
}
/**
* Create a default view to be used for tabs. This is called if a custom tab view is not set via
* {#link #setCustomTabView(int, int)}.
*/
protected TextView createDefaultTabView(Context context) {
TextView textView = new TextView(context);
textView.setGravity(Gravity.CENTER);
textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, TAB_VIEW_TEXT_SIZE_SP);
textView.setTypeface(Typeface.DEFAULT_BOLD);
textView.setLayoutParams(new LinearLayout.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
TypedValue outValue = new TypedValue();
getContext().getTheme().resolveAttribute(android.R.attr.selectableItemBackground,
outValue, true);
textView.setBackgroundResource(outValue.resourceId);
textView.setAllCaps(true);
int padding = (int) (TAB_VIEW_PADDING_DIPS * getResources().getDisplayMetrics().density);
textView.setPadding(padding, padding, padding, padding);
return textView;
}
private void populateTabStrip() {
final PagerAdapter adapter = mViewPager.getAdapter();
final View.OnClickListener tabClickListener = new TabClickListener();
for (int i = 0; i < adapter.getCount(); i++) {
View tabView = null;
TextView tabTitleView = null;
if (mTabViewLayoutId != 0) {
// If there is a custom tab view layout id set, try and inflate it
tabView = LayoutInflater.from(getContext()).inflate(mTabViewLayoutId, mTabStrip,
false);
tabTitleView = (TextView) tabView.findViewById(mTabViewTextViewId);
}
if (tabView == null) {
tabView = createDefaultTabView(getContext());
}
if (tabTitleView == null && TextView.class.isInstance(tabView)) {
tabTitleView = (TextView) tabView;
}
if (mDistributeEvenly) {
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) tabView.getLayoutParams();
lp.width = 0;
lp.weight = 1;
}
tabTitleView.setText(adapter.getPageTitle(i));
tabView.setOnClickListener(tabClickListener);
String desc = mContentDescriptions.get(i, null);
if (desc != null) {
tabView.setContentDescription(desc);
}
mTabStrip.addView(tabView);
if (i == mViewPager.getCurrentItem()) {
tabView.setSelected(true);
}
}
}
public void setContentDescription(int i, String desc) {
mContentDescriptions.put(i, desc);
}
#Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
if (mViewPager != null) {
scrollToTab(mViewPager.getCurrentItem(), 0);
}
}
private void scrollToTab(int tabIndex, int positionOffset) {
final int tabStripChildCount = mTabStrip.getChildCount();
if (tabStripChildCount == 0 || tabIndex < 0 || tabIndex >= tabStripChildCount) {
return;
}
View selectedChild = mTabStrip.getChildAt(tabIndex);
if (selectedChild != null) {
int targetScrollX = selectedChild.getLeft() + positionOffset;
if (tabIndex > 0 || positionOffset > 0) {
// If we're not at the first child and are mid-scroll, make sure we obey the offset
targetScrollX -= mTitleOffset;
}
scrollTo(targetScrollX, 0);
}
}
private class InternalViewPagerListener implements ViewPager.OnPageChangeListener {
private int mScrollState;
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
int tabStripChildCount = mTabStrip.getChildCount();
if ((tabStripChildCount == 0) || (position < 0) || (position >= tabStripChildCount)) {
return;
}
mTabStrip.onViewPagerPageChanged(position, positionOffset);
View selectedTitle = mTabStrip.getChildAt(position);
int extraOffset = (selectedTitle != null)
? (int) (positionOffset * selectedTitle.getWidth())
: 0;
scrollToTab(position, extraOffset);
if (mViewPagerPageChangeListener != null) {
mViewPagerPageChangeListener.onPageScrolled(position, positionOffset,
positionOffsetPixels);
}
}
#Override
public void onPageScrollStateChanged(int state) {
mScrollState = state;
if (mViewPagerPageChangeListener != null) {
mViewPagerPageChangeListener.onPageScrollStateChanged(state);
}
}
#Override
public void onPageSelected(int position) {
if (mScrollState == ViewPager.SCROLL_STATE_IDLE) {
mTabStrip.onViewPagerPageChanged(position, 0f);
scrollToTab(position, 0);
}
for (int i = 0; i < mTabStrip.getChildCount(); i++) {
mTabStrip.getChildAt(i).setSelected(position == i);
}
if (mViewPagerPageChangeListener != null) {
mViewPagerPageChangeListener.onPageSelected(position);
}
}
}
private class TabClickListener implements View.OnClickListener {
#Override
public void onClick(View v) {
for (int i = 0; i < mTabStrip.getChildCount(); i++) {
if (v == mTabStrip.getChildAt(i)) {
mViewPager.setCurrentItem(i);
return;
}
}
}
}
}
SlidingTabStrip.java
class SlidingTabStrip extends LinearLayout {
private static final int DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS = 0;
private static final byte DEFAULT_BOTTOM_BORDER_COLOR_ALPHA = 0x26;
private static final int SELECTED_INDICATOR_THICKNESS_DIPS = 2;
private static final int DEFAULT_SELECTED_INDICATOR_COLOR = 0xFF33B5E5;
private final int mBottomBorderThickness;
private final Paint mBottomBorderPaint;
private final int mSelectedIndicatorThickness;
private final Paint mSelectedIndicatorPaint;
private final int mDefaultBottomBorderColor;
private int mSelectedPosition;
private float mSelectionOffset;
private SlidingTabLayout.TabColorizer mCustomTabColorizer;
private final SimpleTabColorizer mDefaultTabColorizer;
SlidingTabStrip(Context context) {
this(context, null);
}
SlidingTabStrip(Context context, AttributeSet attrs) {
super(context, attrs);
setWillNotDraw(false);
final float density = getResources().getDisplayMetrics().density;
TypedValue outValue = new TypedValue();
context.getTheme().resolveAttribute(android.R.attr.colorForeground, outValue, true);
final int themeForegroundColor = outValue.data;
mDefaultBottomBorderColor = setColorAlpha(themeForegroundColor,
DEFAULT_BOTTOM_BORDER_COLOR_ALPHA);
mDefaultTabColorizer = new SimpleTabColorizer();
mDefaultTabColorizer.setIndicatorColors(DEFAULT_SELECTED_INDICATOR_COLOR);
mBottomBorderThickness = (int) (DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS * density);
mBottomBorderPaint = new Paint();
mBottomBorderPaint.setColor(mDefaultBottomBorderColor);
mSelectedIndicatorThickness = (int) (SELECTED_INDICATOR_THICKNESS_DIPS * density);
mSelectedIndicatorPaint = new Paint();
}
void setCustomTabColorizer(SlidingTabLayout.TabColorizer customTabColorizer) {
mCustomTabColorizer = customTabColorizer;
invalidate();
}
void setSelectedIndicatorColors(int... colors) {
// Make sure that the custom colorizer is removed
mCustomTabColorizer = null;
mDefaultTabColorizer.setIndicatorColors(colors);
invalidate();
}
void onViewPagerPageChanged(int position, float positionOffset) {
mSelectedPosition = position;
mSelectionOffset = positionOffset;
invalidate();
}
#Override
protected void onDraw(Canvas canvas) {
final int height = getHeight();
final int childCount = getChildCount();
final SlidingTabLayout.TabColorizer tabColorizer = mCustomTabColorizer != null
? mCustomTabColorizer
: mDefaultTabColorizer;
// Thick colored underline below the current selection
if (childCount > 0) {
View selectedTitle = getChildAt(mSelectedPosition);
int left = selectedTitle.getLeft();
int right = selectedTitle.getRight();
int color = tabColorizer.getIndicatorColor(mSelectedPosition);
if (mSelectionOffset > 0f && mSelectedPosition < (getChildCount() - 1)) {
int nextColor = tabColorizer.getIndicatorColor(mSelectedPosition + 1);
if (color != nextColor) {
color = blendColors(nextColor, color, mSelectionOffset);
}
// Draw the selection partway between the tabs
View nextTitle = getChildAt(mSelectedPosition + 1);
left = (int) (mSelectionOffset * nextTitle.getLeft() +
(1.0f - mSelectionOffset) * left);
right = (int) (mSelectionOffset * nextTitle.getRight() +
(1.0f - mSelectionOffset) * right);
}
mSelectedIndicatorPaint.setColor(color);
canvas.drawRect(left, height - mSelectedIndicatorThickness, right,height, mSelectedIndicatorPaint);
}
// Thin underline along the entire bottom edge
canvas.drawRect(0, height - mBottomBorderThickness, getWidth(), height, mBottomBorderPaint);
}
/**
* Set the alpha value of the {#code color} to be the given {#code alpha} value.
*/
private static int setColorAlpha(int color, byte alpha) {
return Color.argb(alpha, Color.red(color), Color.green(color), Color.blue(color));
}
/**
* Blend {#code color1} and {#code color2} using the given ratio.
*
* #param ratio of which to blend. 1.0 will return {#code color1}, 0.5 will give an even blend,
* 0.0 will return {#code color2}.
*/
private static int blendColors(int color1, int color2, float ratio) {
final float inverseRation = 1f - ratio;
float r = (Color.red(color1) * ratio) + (Color.red(color2) * inverseRation);
float g = (Color.green(color1) * ratio) + (Color.green(color2) * inverseRation);
float b = (Color.blue(color1) * ratio) + (Color.blue(color2) * inverseRation);
return Color.rgb((int) r, (int) g, (int) b);
}
private static class SimpleTabColorizer implements SlidingTabLayout.TabColorizer {
private int[] mIndicatorColors;
#Override
public final int getIndicatorColor(int position) {
return mIndicatorColors[position % mIndicatorColors.length];
}
void setIndicatorColors(int... colors) {
mIndicatorColors = colors;
}
}
}