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ExpandableRecyclerView - How to expand and collapse multiple CardViews simultaneously

Is it possible to expand and collapse multiple CardViews within a RecyclerView at the same time? I created a header (for my RecyclerView) with two buttons but I'm not sure what needs to go in the click event.
RecyclerView adapter class
public class MyRecyclerAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static final int TYPE_HEADER = 0;
private static final int TYPE_ITEM = 1;
public boolean isSupposedToBeCollapsed;
private Context mContext;
RecyclerViewHeader header;
List<RecyclerViewItem> listItems;
ValueAnimator mAnimator;
public MyRecyclerAdapter(Context context, RecyclerViewHeader header, List<RecyclerViewItem> listItems)
{
this.mContext = context;
this.header = header;
this.listItems = listItems;
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if(viewType == TYPE_HEADER)
{
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.recyclerview_header, parent, false);
return new MyRecyclerAdapter.VHHeader(v);
}
else if(viewType == TYPE_ITEM)
{
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.recyclerview_item, parent, false);
return new MyRecyclerAdapter.VHItem(v);
}
throw new RuntimeException("there is no type that matches the type " + viewType + " + make sure your using types correctly");
}
private RecyclerViewItem getItem(int position)
{
return listItems.get(position);
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
final Typeface iconFont = FontManager.getTypeface(mContext, FontManager.FONTAWESOME);
if (holder instanceof VHHeader)
{
final VHHeader vhHeader = (VHHeader)holder;
vhHeader.btnExpandAll.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(isSupposedToBeCollapsed){
// change visibility to 'VISIBLE'
txtB.setVisibility(View.VISIBLE);
// change direction of chevron to 'up'
txtExpandCollapse.setText(R.string.fa_icon_chevron_up);
// apply animation to the height of 'txtB'
mAnimator = slideAnimator(0, textBHeight);
// start the animation
mAnimator.start();
}
else{
}
}
});
vhHeader.btnCollapseAll.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(isSupposedToBeCollapsed){
// change visibility to 'VISIBLE'
txtB.setVisibility(View.VISIBLE);
// change direction of chevron to 'up'
txtExpandCollapse.setText(R.string.fa_icon_chevron_up);
// apply animation to the height of 'txtB'
mAnimator = slideAnimator(0, textBHeight);
// start the animation
mAnimator.start();
}
else{
}
}
});
}
else if (holder instanceof VHItem)
{
RecyclerViewItem currentItem = getItem(position-1);
final VHItem vhItem = (VHItem)holder;
vhItem.txtA.setText(currentItem.getTitle());
vhItem.txtB.setText(currentItem.getDescription());
vhItem.txtB.setVisibility(View.GONE);
vhItem.txtExpandCollapse.setText(R.string.fa_icon_chevron_down);
vhItem.txtExpandCollapse.setTypeface(iconFont);
//Add onPreDrawListener
vhItem.txtB.getViewTreeObserver().addOnPreDrawListener(
new ViewTreeObserver.OnPreDrawListener() {
#Override
public boolean onPreDraw() {
vhItem.txtB.getViewTreeObserver().removeOnPreDrawListener(this);
vhItem.txtB.setVisibility(View.GONE);
final int widthSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
final int heightSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
vhItem.txtB.measure(widthSpec, heightSpec);
vhItem.textBHeight = vhItem.txtB.getMeasuredHeight();
return true;
}
});
vhItem.cardView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(vhItem.txtB.getVisibility() == View.GONE){
vhItem.expand();
} else {
vhItem.collapse();
}
}
});
vhItem.mLinearLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(vhItem.txtB.getVisibility() == View.GONE){
vhItem.expand();
} else {
vhItem.collapse();
}
}
});
vhItem.txtExpandCollapse.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(vhItem.txtB.getVisibility() == View.GONE){
vhItem.expand();
} else {
vhItem.collapse();
}
}
});
}
}
// need to override this method
#Override
public int getItemViewType(int position) {
if(isPositionHeader(position))
return TYPE_HEADER;
return TYPE_ITEM;
}
private boolean isPositionHeader(int position)
{
return position == 0;
}
// increasing getItemcount to 1. This will be the row of header.
#Override
public int getItemCount() {
return listItems.size()+1;
}
class VHHeader extends RecyclerView.ViewHolder{
Button btnCollapseAll, btnExpandAll;
public VHHeader(View headerView) {
super(headerView);
this.btnCollapseAll = headerView.findViewById(R.id.btn_collapseall);
this.btnExpandAll = headerView.findViewById(R.id.btn_expandall);
}
}
public class VHItem extends RecyclerView.ViewHolder{
CardView cardView;
LinearLayout mLinearLayout;
RecyclerView mRecyclerView;
RelativeLayout mRelativeLayout;
TextView txtExpandCollapse, txtA, txtB;
public int textBHeight;
public VHItem(View itemView) {
super(itemView);
this.cardView = itemView.findViewById(R.id.cv);
this.mLinearLayout = itemView.findViewById(R.id.cardview_tconnections_titlerow);
this.mRelativeLayout = itemView.findViewById(R.id.my_relativelayout);
this.mRecyclerView = itemView.findViewById(R.id.my_recyclerview);
this.txtExpandCollapse = itemView.findViewById(R.id.tv_expandcollapse);
this.txtA = itemView.findViewById(R.id.tv_A);
this.txtB = itemView.findViewById(R.id.tv_B);
}
private void expand() {
// change visibility to 'VISIBLE'
txtB.setVisibility(View.VISIBLE);
// change direction of chevron to 'up'
txtExpandCollapse.setText(R.string.fa_icon_chevron_up);
// apply animation to the height of 'txtB'
mAnimator = slideAnimator(0, textBHeight);
// start the animation
mAnimator.start();
}
private void collapse() {
// change direction of chevron to 'down'
txtExpandCollapse.setText(R.string.fa_icon_chevron_down);
int finalHeight = txtB.getHeight();
ValueAnimator mAnimator = slideAnimator(finalHeight, 0);
mAnimator.addListener(new Animator.AnimatorListener() {
#Override
public void onAnimationEnd(Animator animator) {
txtB.setVisibility(View.GONE);
}
#Override
public void onAnimationStart(Animator animator) {
}
#Override
public void onAnimationCancel(Animator animator) {
}
#Override
public void onAnimationRepeat(Animator animator) {
}
});
mAnimator.start();
}
public ValueAnimator slideAnimator(int start, int end) {
ValueAnimator animator = ValueAnimator.ofInt(start, end);
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
#Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
// update height
int value = (Integer) valueAnimator.getAnimatedValue();
ViewGroup.LayoutParams layoutParams = txtB.getLayoutParams();
layoutParams.height = value;
txtB.setLayoutParams(layoutParams);
}
});
return animator;
}
}
}
Fragment class
public class MyFragment extends android.support.v4.app.Fragment {
private MyRecyclerAdapter adapter;
public MyFragment() {}
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_rv, container, false);
}
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
View v = getView();
assert v != null;
recyclerView = v.findViewById(R.id.my_recyclerview);
linearLayoutManager = new LinearLayoutManager(getActivity());
MyRecyclerAdapter adapter = new MyRecyclerAdapter(getContext(), getHeader(), getListItems());
recyclerView.setLayoutManager(linearLayoutManager);
recyclerView.setAdapter(adapter);
super.onActivityCreated(savedInstanceState);
}
RecyclerView recyclerView;
LinearLayoutManager linearLayoutManager;
public RecyclerViewHeader getHeader()
{
return new RecyclerViewHeader();
}
public List<RecyclerViewItem> getListItems()
{
List<RecyclerViewItem> rvItems = new ArrayList<>();
RecyclerViewItem itemA = new RecyclerViewItem();
itemA.setConnectionMode("Item A");
itemA.setConnectionName("Feature A1");
rvItems.add(itemA);
RecyclerViewItem itemB = new RecyclerViewItem();
itemB.setConnectionMode("Item B");
itemB.setConnectionName("Feature B1\nFeature B2");
rvItems.add(itemB);
RecyclerViewItem itemC = new RecyclerViewItem();
itemC.setConnectionMode("Item C");
itemC.setConnectionName("Feature C1\nFeature C2\nFeature C3");
rvItems.add(itemC);
return rvItems;
}
}

What you can do is, set a variable(boolean) that stores the state of the card (expanded/collapsed) in the RecyclerAdapter code.
Then, in your onBindViewHolder code block, write a piece of code to check if the card should be expanded or collapsed using the above-mentioned variable and the required display code.
Example:
if(isSuppossedToBeCollapsed){
textView.setVisibility = false;
}
else{
textView.setVisibility = true;
}
You can then call notifyDatasetChanged in your RecyclerAdapter code to update the recycler views when you click the button which will redraw the views and reflect the state of the cards(expanded/collapsed) accordingly.
NotifyDatasetChanged Documentation

How to use viewpager to get vertical scroll one item at a time

I want to get vertical scrolling (one item at a time) but can't find they way to implement viewpager on my code. can anyone help me in implementing view pager on my code. I tried using Fragment for getting vertical scroll but no luck. Any help will be appreciated. Thanks in advance.
Here is my code,
MainActivity -
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
seekBar = (SeekBar) findViewById(R.id.seekBar);
songAdapter = new SongAdapter(this, _songs);
recyclerView.setAdapter(songAdapter);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(),
linearLayoutManager.getOrientation());
recyclerView.setLayoutManager(linearLayoutManager);
recyclerView.addItemDecoration(dividerItemDecoration);
songAdapter.setOnItemClickListener(new SongAdapter.OnItemClickListener() {
#Override
public void onItemClick(final Button b, View view, final SongInfo obj, int position) {
if (b.getText().equals("Stop")) {
mediaPlayer.stop();
mediaPlayer.reset();
mediaPlayer.release();
mediaPlayer = null;
b.setText("Play");
} else {
Runnable runnable = new Runnable() {
#Override
public void run() {
try {
mediaPlayer = new MediaPlayer();
mediaPlayer.setDataSource(obj.getSongUrl());
mediaPlayer.prepareAsync();
mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
#Override
public void onPrepared(MediaPlayer mp) {
mp.start();
seekBar.setProgress(0);
seekBar.setMax(mediaPlayer.getDuration());
Log.d("Prog", "run: " + mediaPlayer.getDuration());
}
});
b.setText("Stop");
} catch (Exception e) {
}
}
};
myHandler.postDelayed(runnable, 100);
}
}
});
checkUserPermission();
Thread t = new runThread();
t.start();
}
public class runThread extends Thread {
#Override
public void run() {
while (true) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.d("Runwa", "run: " + 1);
if (mediaPlayer != null) {
seekBar.post(new Runnable() {
#Override
public void run() {
seekBar.setProgress(mediaPlayer.getCurrentPosition());
}
});
Log.d("Runwa", "run: " + mediaPlayer.getCurrentPosition());
}
}
}
}
private void checkUserPermission() {
if (Build.VERSION.SDK_INT >= 23) {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE)
!= PackageManager.PERMISSION_GRANTED) {
requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 123);
return;
}
}
//getMp3Songs();
loadSongs();
}
#Override
public void onRequestPermissionsResult(int requestCode, #NonNull String[] permissions, #NonNull int[] grantResults) {
switch (requestCode) {
case 123:
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
//getMp3Songs();
loadSongs();
} else {
Toast.makeText(this, "Permission Denied", Toast.LENGTH_SHORT).show();
checkUserPermission();
}
break;
default:
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
private void loadSongs() {
Uri uri = MediaStore.Audio.Media.INTERNAL_CONTENT_URI;
// Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
String selection = MediaStore.Audio.Media.IS_MUSIC + "!=0";
Cursor cursor = getContentResolver().query(uri, null, selection, null, null);
if (cursor != null) {
if (cursor.moveToFirst()) {
do {
String name = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DISPLAY_NAME));
String artist = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ARTIST));
String url = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DATA));
Log.i("DATA111", url);
mediaMetadataRetrieve = new MediaMetadataRetriever();
mediaMetadataRetrieve.setDataSource(url);
art = mediaMetadataRetrieve.getEmbeddedPicture();
if (art != null) {
songImage = BitmapFactory.decodeByteArray(art, 0, art.length);
}
SongInfo s = new SongInfo(name, artist, url, songImage);
_songs.add(s);
} while (cursor.moveToNext());
}
cursor.close();
songAdapter = new SongAdapter(MainActivity.this, _songs);
}
}
}
SongAdapter -
private ArrayList<SongInfo> _songs = new ArrayList<SongInfo>();
private Context context;
private OnItemClickListener mOnItemClickListener;
public SongAdapter(Context context, ArrayList<SongInfo> songs) {
this.context = context;
this._songs = songs;
}
public interface OnItemClickListener {
void onItemClick(Button b, View view, SongInfo obj, int position);
}
public void setOnItemClickListener(final OnItemClickListener mItemClickListener) {
this.mOnItemClickListener = mItemClickListener;
}
#Override
public SongHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View myView = LayoutInflater.from(context).inflate(R.layout.row_songs, viewGroup, false);
return new SongHolder(myView);
}
#Override
public void onBindViewHolder(final SongHolder songHolder, final int i) {
final SongInfo s = _songs.get(i);
songHolder.tvSongName.setText(_songs.get(i).getSongname());
songHolder.tvSongArtist.setText(_songs.get(i).getArtistname());
songHolder.tvAlbum_art.setImageBitmap(_songs.get(i).getThaImage());
songHolder.btnAction.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (mOnItemClickListener != null) {
mOnItemClickListener.onItemClick(songHolder.btnAction, v, s, i);
}
}
});
}
#Override
public int getItemCount() {
return _songs.size();
}
public class SongHolder extends RecyclerView.ViewHolder {
TextView tvSongName, tvSongArtist;
Button btnAction;
ImageView tvAlbum_art;
public SongHolder(View itemView) {
super(itemView);
tvSongName = (TextView) itemView.findViewById(R.id.tvSongName);
tvSongArtist = (TextView) itemView.findViewById(R.id.tvArtistName);
tvAlbum_art = (ImageView) itemView.findViewById(R.id.album_art);
btnAction = (Button) itemView.findViewById(R.id.button_action);
}
}
}
VerticalViewPager -
public class VerticalViewPager extends ViewPager {
public VerticalViewPager(Context context) {
this(context, null);
}
public VerticalViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
#Override
public boolean canScrollHorizontally(int direction) {
return false;
}
#Override
public boolean canScrollVertically(int direction) {
return super.canScrollHorizontally(direction);
}
private void init() {
setPageTransformer(true, new VerticalPageTransformer());
setOverScrollMode(View.OVER_SCROLL_NEVER);
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
final boolean toIntercept = super.onInterceptTouchEvent(flipXY(ev));
flipXY(ev);
return toIntercept;
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
final boolean toHandle = super.onTouchEvent(flipXY(ev));
flipXY(ev);
return toHandle;
}
private MotionEvent flipXY(MotionEvent ev) {
final float width = getWidth();
final float height = getHeight();
final float x = (ev.getY() / height) * width;
final float y = (ev.getX() / width) * height;
ev.setLocation(x, y);
return ev;
}
private static final class VerticalPageTransformer implements ViewPager.PageTransformer {
#Override
public void transformPage(View view, float position) {
final int pageWidth = view.getWidth();
final int pageHeight = view.getHeight();
if (position < -1) {
view.setAlpha(0);
} else if (position <= 1) {
view.setAlpha(1);
view.setTranslationX(pageWidth * -position);
float yPosition = position * pageHeight;
view.setTranslationY(yPosition);
} else {
view.setAlpha(0);
}
}
}
}

Start with this simple example:
1) MnnnnnActivity.class:----------
public class MnnnnnActivity extends AppCompatActivity {
private VerticalViewPager vp;
private MPagerAdapter mPagerAdapter;
private int lastPage = 0;
private List<String> songs = new ArrayList<String>();
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layout5);
vp = (VerticalViewPager) findViewById(R.id.vp);
for(int i = 0 ; i<10 ; i++){
songs.add(i , "song " + i);
}
mPagerAdapter = new MPagerAdapter(getApplicationContext(), songs);
vp.setAdapter(mPagerAdapter);
vp.setOffscreenPageLimit(1);
vp.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
if(lastPage > position){ //left
}else{ // right
}
lastPage = position;
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
}
}
2) MPagerAdapter.class:-----
public class MPagerAdapter extends PagerAdapter {
private Context mContext;
private List<String> songs = new ArrayList<String>();
public MPagerAdapter(Context context , List<String> songs) {
mContext = context;
this.songs = songs;
}
#Override
#NonNull
public Object instantiateItem(#NonNull final ViewGroup collection, final int position) {
LayoutInflater inflater = LayoutInflater.from(mContext);
View layout = (View) inflater.inflate(R.layout.layout_list, collection, false);
TextView tv = (TextView) layout.findViewById(R.id.tv_song);
tv.setText(songs.get(position));
Button b = (Button) layout.findViewById(R.id.b_song);
b.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(mContext , "Play " + songs.get(position) , Toast.LENGTH_LONG).show();
}
});
collection.addView(layout);
return layout;
}
#Override
public void destroyItem(ViewGroup collection, int position, Object view) {
collection.removeView((View) view);
}
#Override
public int getCount() {
return songs.size();
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
#Override
public CharSequence getPageTitle(int position) {
return songs.get(position);
}
}
3) VerticalViewPager.class:-------
//https://stackoverflow.com/questions/13477820/android-vertical-viewpager
public class VerticalViewPager extends ViewPager {
public VerticalViewPager(Context context) {
super(context);
init();
}
public VerticalViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
setPageTransformer(true, new VerticalPageTransformer());
setOverScrollMode(OVER_SCROLL_NEVER);
}
private MotionEvent swapXY(MotionEvent ev) {
float width = getWidth();
float height = getHeight();
float newX = (ev.getY() / height) * width;
float newY = (ev.getX() / width) * height;
ev.setLocation(newX, newY);
return ev;
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
boolean intercepted = super.onInterceptTouchEvent(swapXY(ev));
swapXY(ev);
//https://stackoverflow.com/questions/15365915/viewpager-nested-in-viewpager
int action = ev.getAction();
switch (action) {
case MotionEvent.ACTION_UP:
this.getParent().requestDisallowInterceptTouchEvent(true);
break;
case MotionEvent.ACTION_DOWN:
this.getParent().requestDisallowInterceptTouchEvent(true);
break;
case MotionEvent.ACTION_MOVE:
this.getParent().requestDisallowInterceptTouchEvent(true);
break;
}
return intercepted;
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
return super.onTouchEvent(swapXY(ev));
}
}
4) VerticalPageTransformer.class:-----------
//https://stackoverflow.com/questions/13477820/android-vertical-viewpager
public class VerticalPageTransformer implements ViewPager.PageTransformer {
#Override
public void transformPage(View view, float position) {
int pageWidth = view.getWidth();
int pageHeight = view.getHeight();
if (position < -1) { // [-Infinity,-1)
// This page is way off-screen to the left.
view.setAlpha(0);
} else if (position <= 1) { // [-1,1]
view.setAlpha(1);
// Counteract the default slide transition
view.setTranslationX(pageWidth * -position);
//set Y position to swipe in from top
float yPosition = position * view.getHeight();
view.setTranslationY(yPosition);
} else { // (1,+Infinity]
// This page is way off-screen to the right.
view.setAlpha(0);
}
}
}
5) layout5.xml:--------
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.example.admin.accessories.VerticalViewPager
android:id="#+id/vp"
android:layout_width="match_parent"
android:layout_height="match_parent">
</com.example.admin.accessories.VerticalViewPager>
</android.support.constraint.ConstraintLayout>
6) layout_list.xml:--------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:orientation="vertical"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="20dp"
android:text="SName"
android:layout_marginBottom="20dp"
android:id="#+id/tv_song"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Play"
android:id="#+id/b_song"/>
</LinearLayout>
7) Output:---------

Simple solution is try rotating viewpager and its child view
mViewPager.setRotation(90);
It will rotate view pager and it's child views as well. Now rotate child view again in opposite direction.
childView.setRotation(270);

FragmentStatePageAdapter Retaining interface attached to fragment

I'm using a FragmentStatePagerAdapter (for the ViewPager), The fragments which are attached to the ViewPager have fields which I wish to pass the data back to the Activity. My problem lies in that the interface objects which I pass to the fragments are lost once the device has been rotated.
My question is how do I retain the interface objects.
Now the obligatory code snippets:
The Activity:
public class TheActivity extends AppCompatActivity {
static final int PageCount = 2;
static final int PageA = 0;
static final int PageB = 1;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
viewPager.setAdapter(new FragmentStatePagerAdapter(getSupportFragmentManager()) {
#Override
public Fragment getItem(int position) {
switch (position) {
case PageA: {
PageAFragment fragment = PageAFragment.CreateFragment();
fragment.setDataListener(new PageAFragment.DataListener() {
#Override
public void OnPageADataChange(String value) {
PageAData = value;
}
});
return fragment;
}
case PageB: {
PageBFragment fragment = PageBFragment.CreateFragment(2);
fragment.setDataListener(new PageBFragment.DataListener() {
#Override
public void OnPageAOneDataChange(String value) {
PageBDataOne = value;
}
#Override
public void OnPageATwoDataChange(String value) {
PageBDataTwo = value;
}
});
return fragment;
}
}
return null;
}
#Override
public int getCount() {
return PageCount;
}
});
}
}
The Fragments:
public class PageAFragment extends Fragment {
private DataListener mListener;
public static PageAFragment CreateFragment() {
return new PageAFragment();
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.page_a, container, false);
EditText editText = (EditText) view.findViewById(R.id.edittext_data_a);
editText.setOnEditorActionListener(new TextView.OnEditorActionListener() {
#Override
public boolean onEditorAction(TextView v, int actionID, KeyEvent event) {
if (actionID == EditorInfo.IME_ACTION_DONE)
mListener.OnPageADataChange(editText.getText().toString());
return false;
}
});
return view;
}
public void setDataListener(DataListener dataListener) {
mListener = dataListener;
}
public interface DataListener {
void OnPageADataChange(String value);
}
}
public class PageBFragment extends Fragment {
private DataListener mListener;
public static PageBFragment CreateFragment(int data) {
PageBFragment fragment = new PageBFragment();
Bundle bundle = new Bundle();
bundle.putInt("Data", data);
fragment.setArguments(bundle);
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.page_b, container, false);
EditText editTextOne = (EditText) view.findViewById(R.id.edittext_data_b_one);
editTextOne.setOnEditorActionListener(new TextView.OnEditorActionListener() {
#Override
public boolean onEditorAction(TextView v, int actionID, KeyEvent event) {
if (actionID == EditorInfo.IME_ACTION_DONE)
mListener.OnPageAOneDataChange(editTextOne.getText().toString());
return false;
}
});
EditText editTextTwo = (EditText) view.findViewById(R.id.edittext_data_b_two);
editTextTwo.setOnEditorActionListener(new TextView.OnEditorActionListener() {
#Override
public boolean onEditorAction(TextView v, int actionID, KeyEvent event) {
if (actionID == EditorInfo.IME_ACTION_DONE)
mListener.OnPageATwoDataChange(editTextTwo.getText().toString());
return false;
}
});
return view;
}
public void setDataListener(DataListener dataListener) {
mListener = dataListener;
}
public interface DataListener {
void OnPageAOneDataChange(String value);
void OnPageATwoDataChange(String value);
}
}

I think you should re read this https://developer.android.com/training/basics/fragments/communicating.html.
Let the activity implement the interfaces and use the onAttach() onDetach() methods to reset the reference of the callback to the activity.
With your code if you try to retain the fragments' state (setRetainInstance(true), onsaveInstanceState()) which includes the interface objects you will probably have issues with memory leak or your code will become too complicated for no reason.

Overriding getContextMenuInfo() from custom Adapter

I am building a list that had to be able to reorder the item's position.
Fortunately for me, I've found an external library which has exactly what I needed.
Unfortunately, I could not implement a delete item action using onContextItemSelected() because menuInfo keeps always returning null, so I cannot read the position of selected item I wish to delete.
This user blog post gave a solution by overriding getContextMenuInfo().
If item.getMenuInfo() is null in onContextItemSelected(MenuItem item) method, I guess you are using custom ListView or GridView instead of android default ones. In such case, your custom View is not implementing getContextMenuInfo() method. Don’t worry we can fix that if you have its source. Open the view file and override the method getContextMenuInfo().
I have tried this in many ways, but it seems I am doing things wrong.
Is this the only solution or am I missing something?
Activity
public class SurveyAdd extends AppCompatActivity {
private ArrayList<Pair<Long, String>> mItemArray = new ArrayList<>();
private DragListView mDragListView;
ItemAdapter listAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_survey_add);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
mDragListView = (DragListView) findViewById(R.id.surveyadd_list);
mDragListView.getRecyclerView().setVerticalScrollBarEnabled(true);
mDragListView.setDragListListener(new DragListView.DragListListener() {
#Override
public void onItemDragStarted(int position) {
}
#Override
public void onItemDragEnded(int fromPosition, int toPosition) {
if (fromPosition != toPosition) {
setSurveyChange(true);
}
}
});
mDragListView.setCanDragHorizontally(false);
mDragListView.setCustomDragItem(new MyDragItem(context, R.layout.item_survey_add));
mDragListView.setLayoutManager(new LinearLayoutManager(context));
mDragListView.setLayoutManager(new LinearLayoutManager(context));
ItemAdapter listAdapter = new ItemAdapter(mItemArray, R.layout.item_survey_add, R.id.item_add_image_button, false);
mDragListView.setAdapter(listAdapter, true);
registerForContextMenu(mDragListView);
}
#Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_survey_add_item, menu);
}
#Override
public boolean onContextItemSelected(MenuItem item) {
AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
switch (item.getItemId()) {
case R.id.surveyadd_action_delete:
if (item.getMenuInfo() == null) {
Toast.makeText(SurveyAdd.this, "NULL", Toast.LENGTH_SHORT).show();
}
int position = info.position; // CAN'T USE THIS, ALWAYS THROWS NULLPOINTEREXCEPTION
Toast.makeText(SurveyAdd.this, "" + position, Toast.LENGTH_SHORT).show();
return true;
}
}
}
// The activity was simplified for posting
ItemAdapter
imported and edited class
public class ItemAdapter extends DragItemAdapter<Pair<Long, String>, ItemAdapter.ViewHolder> {
private int mLayoutId;
private int mGrabHandleId;
public ItemAdapter(ArrayList<Pair<Long, String>> list, int layoutId, int grabHandleId, boolean dragOnLongPress) {
super(dragOnLongPress);
mLayoutId = layoutId;
mGrabHandleId = grabHandleId;
setHasStableIds(true);
setItemList(list);
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(mLayoutId, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
super.onBindViewHolder(holder, position);
String text = mItemList.get(position).second;
String[] separated = text.split("::");
holder.mText.setText(separated[1]);
holder.itemView.setTag(text);
}
#Override
public long getItemId(int position) {
return mItemList.get(position).first;
}
public class ViewHolder extends DragItemAdapter<Pair<Long, String>, ItemAdapter.ViewHolder>.ViewHolder {
public TextView mText;
public ImageView mIcon;
public ViewHolder(final View itemView) {
super(itemView, mGrabHandleId);
mText = (TextView) itemView.findViewById(R.id.item_add_question);
mIcon = (ImageView) itemView.findViewById(mGrabHandleId);
}
#Override
public void onItemClicked(View view) {
}
#Override
public boolean onItemLongClicked(View view) {
return false;
}
}
}
DragListView
imported and locked class
public class DragListView extends FrameLayout {
public interface DragListListener {
void onItemDragStarted(int position);
void onItemDragEnded(int fromPosition, int toPosition);
}
private DragItemRecyclerView mRecyclerView;
private DragListListener mDragListListener;
private DragItem mDragItem;
private boolean mDragEnabled = true;
private float mTouchX;
private float mTouchY;
public DragListView(Context context) {
super(context);
}
public DragListView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public DragListView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
#Override
protected void onFinishInflate() {
super.onFinishInflate();
mDragItem = new DragItem(getContext());
mRecyclerView = createRecyclerView();
mRecyclerView.setDragItem(mDragItem);
addView(mRecyclerView);
addView(mDragItem.getDragItemView());
}
#Override
public boolean onInterceptTouchEvent(MotionEvent event) {
boolean retValue = handleTouchEvent(event);
return retValue || super.onInterceptTouchEvent(event);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
boolean retValue = handleTouchEvent(event);
return retValue || super.onTouchEvent(event);
}
private boolean handleTouchEvent(MotionEvent event) {
mTouchX = event.getX();
mTouchY = event.getY();
if (isDragging()) {
switch (event.getAction()) {
case MotionEvent.ACTION_MOVE:
mRecyclerView.onDragging(event.getX(), event.getY());
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
mRecyclerView.onDragEnded();
break;
}
return true;
}
return false;
}
private DragItemRecyclerView createRecyclerView() {
final DragItemRecyclerView recyclerView = (DragItemRecyclerView) LayoutInflater.from(getContext()).inflate(R.layout.drag_item_recycler_view, this, false);
recyclerView.setMotionEventSplittingEnabled(false);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setVerticalScrollBarEnabled(false);
recyclerView.setHorizontalScrollBarEnabled(false);
recyclerView.setDragItemListener(new DragItemRecyclerView.DragItemListener() {
private int mDragStartPosition;
#Override
public void onDragStarted(int itemPosition, float x, float y) {
getParent().requestDisallowInterceptTouchEvent(true);
mDragStartPosition = itemPosition;
if (mDragListListener != null) {
mDragListListener.onItemDragStarted(itemPosition);
}
}
#Override
public void onDragging(int itemPosition, float x, float y) {
}
#Override
public void onDragEnded(int newItemPosition) {
if (mDragListListener != null) {
mDragListListener.onItemDragEnded(mDragStartPosition, newItemPosition);
}
}
});
return recyclerView;
}
public RecyclerView getRecyclerView() {
return mRecyclerView;
}
public DragItemAdapter getAdapter() {
if (mRecyclerView != null) {
return (DragItemAdapter) mRecyclerView.getAdapter();
}
return null;
}
public void setAdapter(DragItemAdapter adapter, boolean hasFixedItemSize) {
mRecyclerView.setHasFixedSize(hasFixedItemSize);
mRecyclerView.setAdapter(adapter);
adapter.setDragEnabled(mDragEnabled);
adapter.setDragStartedListener(new DragItemAdapter.DragStartedListener() {
#Override
public void onDragStarted(View itemView, long itemId) {
mRecyclerView.onDragStarted(itemView, itemId, mTouchX, mTouchY);
}
});
}
public void setLayoutManager(RecyclerView.LayoutManager layout) {
mRecyclerView.setLayoutManager(layout);
}
public void setDragListListener(DragListListener listener) {
mDragListListener = listener;
}
public boolean isDragEnabled() {
return mDragEnabled;
}
public void setDragEnabled(boolean enabled) {
mDragEnabled = enabled;
if (mRecyclerView.getAdapter() != null) {
((DragItemAdapter) mRecyclerView.getAdapter()).setDragEnabled(mDragEnabled);
}
}
public void setCustomDragItem(DragItem dragItem) {
removeViewAt(1);
DragItem newDragItem;
if (dragItem != null) {
newDragItem = dragItem;
} else {
newDragItem = new DragItem(getContext());
}
newDragItem.setCanDragHorizontally(mDragItem.canDragHorizontally());
newDragItem.setSnapToTouch(mDragItem.isSnapToTouch());
mDragItem = newDragItem;
mRecyclerView.setDragItem(mDragItem);
addView(mDragItem.getDragItemView());
}
public boolean isDragging() {
return mRecyclerView.isDragging();
}
public void setCanDragHorizontally(boolean canDragHorizontally) {
mDragItem.setCanDragHorizontally(canDragHorizontally);
}
public void setSnapDragItemToTouch(boolean snapToTouch) {
mDragItem.setSnapToTouch(snapToTouch);
}
public void setCanNotDragAboveTopItem(boolean canNotDragAboveTop) {
mRecyclerView.setCanNotDragAboveTopItem(canNotDragAboveTop);
}
public void setScrollingEnabled(boolean scrollingEnabled) {
mRecyclerView.setScrollingEnabled(scrollingEnabled);
}
}

This is an old post but i figured it out using that same draglistview.
Im using Xamarin but it's close enough to the same. Just type the C# in Java as necessary:
protected override IContextMenuContextMenuInfo ContextMenuInfo
{
get
{
IContextMenuContextMenuInfo menuInfo = base.ContextMenuInfo;
if (menuInfo == null)
{
IListAdapter adapter = Adapter;
int pos = GetPositionForView(selectedView);
menuInfo = new AdapterContextMenuInfo(selectedView, pos, adapter.GetItemId(pos));
}
return menuInfo;
}
}
public void OnLongPress(MotionEvent e){
int position = PointToPosition(mDownX, mDownY);
int itemNum = position - FirstVisiblePosition;
selectedView = GetChildAt(itemNum); //class variable
...
}

Find out which item in ListView was swiped

I am trying to swipe a row in my ListView, identify its text and perform certain actions. I am able to detect left/right swipes but how to I go about identifying the text for that swiped row? I am not able to identify its location unlike using onItemClickListener where I could use the position variable.
MainActivity Class
ListView orderListView;
ArrayList<String> orders;
ArrayAdapter<String> adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_order_stock);
orderListView = (ListView)findViewById(R.id.orderListView);
orders = new ArrayList<>();
orders.add("order 1");
orders.add("order 2");
orders.add("order 3");
adapter = new ArrayAdapter<>(getApplicationContext(), android.R.layout.simple_list_item_1, orders);
orderListView.setAdapter(adapter);
OnSwipeTouchListener onSwipeTouchListener = new OnSwipeTouchListener(this, orderListView);
orderListView.setOnTouchListener(onSwipeTouchListener);
}
OnSwipeTouchListener Class
public class OnSwipeTouchListener implements View.OnTouchListener {
ListView list;
private GestureDetector gestureDetector;
private Context context;
public OnSwipeTouchListener(Context ctx, ListView list) {
gestureDetector = new GestureDetector(ctx, new GestureListener());
context = ctx;
this.list = list;
}
public OnSwipeTouchListener() {
super();
}
#Override
public boolean onTouch(View v, MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
public void onSwipeRight(int pos) {
Log.i("zxR", "right");
}
public void onSwipeLeft() {
Log.i("zxL", "left");
}
private final class GestureListener extends GestureDetector.SimpleOnGestureListener {
private static final int SWIPE_THRESHOLD = 100;
private static final int SWIPE_VELOCITY_THRESHOLD = 100;
#Override
public boolean onDown(MotionEvent e) {
return true;
}
private int getPostion(MotionEvent e1) {
return list.pointToPosition((int) e1.getX(), (int) e1.getY());
}
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
float distanceX = e2.getX() - e1.getX();
float distanceY = e2.getY() - e1.getY();
if (Math.abs(distanceX) > Math.abs(distanceY) && Math.abs(distanceX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
if (distanceX > 0)
onSwipeRight(getPostion(e1));
else
onSwipeLeft();
return true;
}
return false;
}
}
}

Try this, I think this might help:
Include ArrayAdapter in the argument of the constructor of OnSwipeTouchListener and pass the adapter of the ListView from the main activity
Then add this code to your onFling()
float distanceX = e2.getX() - e1.getX();
float distanceY = e2.getY() - e1.getY();
int id = list.pointToPosition((int) e1.getX(), (int) e1.getY());
String text=adapter.getItem(id);
Toast.makeText(context,"Text:"+text,Toast.LENGTH_SHORT).show();

Use the new RecyclerView instead of ListView as it have simple api for gestures and animations.
The same question for RecyclerView:
https://stackoverflow.com/a/30601554/2627680