Develop Reference

How can I have scrolling to last page working properly in a paginated scroll in android ListView

Attention! This question is not about dynamic loading of items into a very long ListView.
This is about adding PageUP and PageDown buttons to a ListView so that user can touch the button and scroll ListView page by page. Page means all fully and partially visible items on the screen.
I have partially implemented this in the following code, but my problem is that when I have lets say 10 items of approximately same height in the listview and 7 of them fit into the first page, then when I press PgDown button, user expects that item 8 to be on top of the screen (next page), but because there are only 10 items, ListView scrolls to the bottom of the list and because there is no extra scroll space I have item number 4 on top.
What is the best solution in this situation?
Should I add one item to the end of the list which will make the last page the height of the screen or there are any better options?
Here is my code:
public class cPaginatedListViewHelper {
Activity m_parentActivity;
private ListView mList;
//controls
private LinearLayout m_PagingLL;
//buttons
private ImageButton m_btnPrevPage;
private ImageButton m_btnNextPage;
private ImageButton m_btnExitPaginatedMode;
public cPaginatedListViewHelper(ListActivity mParent) {
this.m_parentActivity = mParent;
m_btnPrevPage=(ImageButton) mParent.findViewById(R.id.btnPrevPage);
m_btnNextPage=(ImageButton) mParent.findViewById(R.id.btnNextPage);
m_btnExitPaginatedMode =(ImageButton) mParent.findViewById(R.id.btnClosePage);
if(m_btnPrevPage!=null) {
m_btnPrevPage.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
showSiblingPage(-1);
}
});
m_btnPrevPage.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View v) {
mList.smoothScrollToPosition(0);
return true;
}
}
);
}
if(m_btnNextPage!=null) {
m_btnNextPage.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
showSiblingPage(1);
}
});
m_btnNextPage.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View v) {
mList.smoothScrollToPosition(mList.getCount());
return true;
}
}
);
}
m_btnExitPaginatedMode.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
setEnabled(false);
m_PagingLL.setVisibility(View.GONE);
}
});
mList=mParent.getListView();
m_PagingLL = (LinearLayout) mParent.findViewById(R.id.pageControls);
}
public void updateControlsVisibility()
{
ViewTreeObserver observer = mList.getViewTreeObserver();
observer.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
if (willMyListScroll()) {
boolean psm = isEnabled();
//enable or disable
m_PagingLL.setVisibility( psm ? View.VISIBLE : View.GONE);
((View)mList).setVerticalScrollbarPosition(psm ? View.SCROLLBAR_POSITION_LEFT: View.SCROLLBAR_POSITION_RIGHT);
}
else
{
m_PagingLL.setVisibility(View.GONE);
((View)mList).setVerticalScrollbarPosition(View.SCROLLBAR_POSITION_RIGHT);
}
}
});
}
private boolean willMyListScroll() {
try {
int pos = mList.getLastVisiblePosition();
if (mList.getChildAt(pos).getBottom() > mList.getHeight()) {
return true;
} else {
return false;
}
} catch (Exception e) {
e.printStackTrace();
}
return false;
}
private void showSiblingPage(int shift)
{
if(mList!=null) {
int iScrollPageHeight = mList.getHeight();
mList.scrollListBy(iScrollPageHeight * shift);
}
}
public void setEnabled(boolean psm) {
MyApp.Pref.edit().putBoolean("PSModeEnabled", psm).commit();
}
public boolean isEnabled(){
return MyApp.Pref.getBoolean("PSModeEnabled", false);
}
public void pagedScrollEnableDisable() {
boolean pagingEnabled = isEnabled();
pagingEnabled=!pagingEnabled;
setEnabled(pagingEnabled);
m_PagingLL.setVisibility( pagingEnabled ? View.VISIBLE : View.GONE);
updateControlsVisibility();
}
}

I finished up with using ListView's footer with variable height as shown in the following code:
LayoutInflater inflater = m_parentActivity.getLayoutInflater();
m_footerView = inflater.inflate(R.layout.listview_paged_overscroll, mList, false );
ViewGroup.LayoutParams lp =m_footerView.getLayoutParams();
if(m_tvPageNum!=null) recalcPagination();
if(lp!=null) lp.height = m_extraScrollFooterHeight;
int iFooters = mList.getFooterViewsCount();
if(iFooters==0) mList.addFooterView(m_footerView);

RecyclerView index not updating while removing item using FirebaseRecycleradapter

I have implemented FirebaseRecyclerAdapter for a dynamic recyclerView and while I am trying to delete an item from the list, initially items at wrong indexes are getting deleted and after more items deletion, i am getting IndexOutOfBoundsException. I have already tried all solutions I found which can be seen as commented inside populateViewHolder() method. Please, if you have to downvote, at least give a proper answer and downvote it as I have already tried all solutions possible. Below I am posting my code. Please have a look.
Check the delete.setOnClickListener():
adapter = new FirebaseRecyclerAdapter<Slc, viewHolder>(
Slc.class,
R.layout.single_slc_row,
viewHolder.class,
FirebaseDatabase.getInstance().getReference().child("DCU")) {
#Override
protected void populateViewHolder(final viewHolder viewHolder, final Slc model, final int position)
{
//expand collapse
viewHolder.vis.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v)
{
// ViewAnimationsUtils.expand(viewHolder.inv);
viewHolder.collapse.setVisibility(View.VISIBLE);
viewHolder.inv.setVisibility(View.VISIBLE);
}
});
viewHolder.collapse.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v)
{
// ViewAnimationsUtils.collapse(inv);
viewHolder.inv.setVisibility(View.GONE);
viewHolder.collapse.setVisibility(View.GONE);
}
});
String s=adapter.getRef(position).getKey();
viewHolder.name.setText(s);
//dimming get
viewHolder.dimming.setProgress(model.getPercentage());
//on off get
if(model.getON_OFF()==1)
{
viewHolder.onOff.setChecked(true);
}
else if(model.getON_OFF()==0)
{
viewHolder.onOff.setChecked(false);
}
//dimming set
//viewHolder.dimming.incrementProgressBy(10);
viewHolder.showProgress.setText( viewHolder.dimming.getProgress()+"%");
viewHolder.dimming.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
#Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser)
{
if(position!=RecyclerView.NO_POSITION)
{
if(seekBar.isShown() && fromUser)
{
progress= (progress/10)*10;
adapter.getRef(position).child("Percentage").setValue(progress);
viewHolder.showProgress.setText(progress+"%");
}
}
}
#Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
#Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
viewHolder.onOff.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView,
boolean isChecked) {
if(buttonView.isPressed() &&isChecked){
adapter.getRef(position).child("ON_OFF").setValue(1);
}else{
adapter.getRef(position).child("ON_OFF").setValue(0);
}
}
});
viewHolder.delete.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v)
{
final Dialog dialog = new Dialog(myContext);
dialog.setTitle("Delete Slc?");
dialog.setContentView(R.layout.delete_slc);
dialog.setCancelable(false);
Window window = dialog.getWindow();
if(window == null) return;
WindowManager.LayoutParams lp = new WindowManager.LayoutParams();
lp.copyFrom(dialog.getWindow().getAttributes());
lp.width = WindowManager.LayoutParams.MATCH_PARENT;
lp.height = WindowManager.LayoutParams.WRAP_CONTENT;
lp.gravity = Gravity.CENTER;
dialog.getWindow().setAttributes(lp);
TextView delete = (TextView)dialog.findViewById(R.id.deleteSlc);
final String key= adapter.getRef(position).getKey();
delete.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v)
{
// int pos = viewHolder.getAdapterPosition();
ref.child(key).setValue(null);
// int selectedItems = position;
// for (int i = selectedItems; i >= selectedItems; i--) {
// adapter.getRef(i).removeValue();
adapter.notifyItemRemoved(position);
// }
// adapter.getRef(position).removeValue();
//
// adapter.notifyItemRemoved(position);
// adapter.notifyDataSetChanged();
dialog.dismiss();
}
});
TextView dialogButton = (TextView) dialog.findViewById(R.id.canceld);
// if button is clicked, close the custom dialog
dialogButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v)
{
dialog.dismiss();
}
});
dialog.show();
}
});
}
};
slcList.setAdapter(adapter);
The exception I am getting after deleting some items:
java.lang.IndexOutOfBoundsException: Invalid index 2, size is 2
at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
at java.util.ArrayList.get(ArrayList.java:308)
at com.firebase.ui.database.FirebaseArray.getItem(FirebaseArray.java:52)
at com.firebase.ui.database.FirebaseRecyclerAdapter.getRef(FirebaseRecyclerAdapter.java:150)

The error is caused by usage of position object inside of function not directly under populateViewHolder. Like in this one: (but not limited to)
protected void populateViewHolder(final viewHolder viewHolder, final Slc model, final int position) {
// here position object is valid
...
viewHolder.dimming.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
#Override
public void onProgressChanged( ... ) {
// but here, position object is likely to be incorrect
// especially when you add/remove item of list
}
...
}
And the solution is simply to replace all the position objects that are not directly under populateViewHolder into viewHolder.getAdapterPosition().
Note: I copy it from my comment in case others seek for answer and miss the comment

ListView not getting updated after insertion of entries in SqliteDatabase

I have read a many posts on this topic but none is helping.I have a listview and I have a dialog.The dialog contains three Edittext fields one for name,description and date.I have two Buttons on the dialog save and cancel. On clicking the save button , insert the data in database but listview doesn't get updated.
This is the method where I specify the function of the save button :
save_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
selectedModel=new Model();
selectedModel.setTask_title(task_Title.getText().toString());
selectedModel.setTask_description(task_Description.getText().toString());
selectedModel.setTask_date(task_Date.getText().toString());
db.insertTask(selectedModel);
//Toast.makeText(getApplicationContext(),"model ="+selectedModel.getTask_title(),Toast.LENGTH_LONG).show();
dialog.dismiss();
//myAdapter.notifyDataSetChanged();
}
});
I have tried using .notifyDataSetChanged() but it didn't work.
This is my main code where I specify all the functions :
public class SecondScreen extends ListActivity implements AppCompatCallback,AdapterView.OnItemClickListener {
private Toolbar bar;
private AppCompatDelegate delegate;
List<Model> list;
ArrayAdapter<String> myAdapter;
final Context context=this;
Model selectedModel;
AGSQLiteHelper db;
private EditText task_Title,task_Description,task_Date;
#Override
protected void onCreate(Bundle savedInstanceState) {
delegate=AppCompatDelegate.create(this,this);
super.onCreate(savedInstanceState);
delegate.setContentView(R.layout.activity_second_screen);
bar=(Toolbar)findViewById(R.id.toolbarID);
delegate.setSupportActionBar(bar);
ActionBar ab=delegate.getSupportActionBar();
ab.setDisplayHomeAsUpEnabled(true);
db=new AGSQLiteHelper(this);
db.onUpgrade(db.getWritableDatabase(),1,2);
db.createTask(new Model("abcde","description abcde","19/11/12"));
db.createTask(new Model("bcdese","description bcdese","18/12/12"));
db.createTask(new Model("mnbv","description mnbv","2/11/10"));
db.createTask(new Model("poiuy","description poiuy","1/5/6"));
list=db.getAllTasks();
List<String> listTitle=new ArrayList<String>();
for(int i=0;i<list.size();i++){
listTitle.add(i,list.get(i).getTask_title());
}
myAdapter=new ArrayAdapter<String>(this,R.layout.row,R.id.tasktitleTextID,listTitle);
getListView().setOnItemClickListener(this);
setListAdapter(myAdapter);
}
#Override
public void onSupportActionModeStarted(ActionMode mode) {
}
#Override
public void onSupportActionModeFinished(ActionMode mode) {
}
#Nullable
#Override
public ActionMode onWindowStartingSupportActionMode(ActionMode.Callback callback) {
return null;
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) { }
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if(item.getItemId()==R.id.add){
Toast.makeText(getApplicationContext(),"Add was clicked",Toast.LENGTH_LONG).show();
final Dialog dialog=new Dialog(context);
dialog.setContentView(R.layout.custom_dialog);
dialog.setTitle("Dialog");
Button save_button=(Button)dialog.findViewById(R.id.saveButtonID);
Button cancel_button=(Button)dialog.findViewById(R.id.cancelButtonID);
task_Title=(EditText)dialog.findViewById(R.id.titleEditTextID);
task_Description=(EditText)dialog.findViewById(R.id.descriptionEditTextID);
task_Date=(EditText)dialog.findViewById(R.id.dateEditTextID);
dialog.show();
save_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
selectedModel=new Model();
selectedModel.setTask_title(task_Title.getText().toString());
selectedModel.setTask_description(task_Description.getText().toString());
selectedModel.setTask_date(task_Date.getText().toString());
db.insertTask(selectedModel);
//Toast.makeText(getApplicationContext(),"model ="+selectedModel.getTask_title(),Toast.LENGTH_LONG).show();
dialog.dismiss();
//myAdapter.notifyDataSetChanged();
}
});
cancel_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
dialog.dismiss();
}
});
}
if(item.getItemId()==R.id.done){
Toast.makeText(getApplicationContext(),"Done was clicked",Toast.LENGTH_LONG).show();
}
return true;
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu,menu);
return true;
}
}
Any suggestions?

you need to add the new entry into the listTitle used by the adapter
db.insertTask(selectedModel);
dialog.dismiss();
listTitle.add(selectedModel.getTask_title());
myAdapter.notifyDataSetChanged();
so make your listTitle global to the class so that you can use it inside other functions
public class SecondScreen extends ListActivity...{
private EditText task_Title;
private List<String> listTitle;
// declare list like this as global to class
... onCreate(..){
listTitle=new ArrayList<String>();
}
}

Changing a textview above viewpager depending on what page?

I have an activity that has 2 buttons (Previous, Next) and a text view in between the two. Below that is a viewpager.
I would like to change the textview to the title of whatever page they are on.
Here is the class where it all happens:
public class MyWorkout extends BaseActivity {
NonSwipeableViewPager vp;
TextView txtViewTitle;
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.my_workout);
mToolBar = activateToolbar();
setUpNavigationDrawer();
getSupportActionBar().setTitle("My Workout");
Intent intent = getIntent();
String workouttitle = intent.getStringExtra("workout");
switch(workouttitle) {
case "w29" : {
getSupportActionBar().setTitle("My Workout - Workout 29");
break;
}
case "w30" : {
getSupportActionBar().setTitle("My Workout - Workout 30");
break;
}
}
Button btnPrev = (Button) findViewById(R.id.btnPrevious);
Button btnNext = (Button) findViewById(R.id.btnNext);
vp = (NonSwipeableViewPager) findViewById(R.id.view_pager);
txtViewTitle = (TextView) findViewById(R.id.txtViewTitle);
this.addPages(vp);
//THIS IS WHAT I HAVE TRIED
if (vp.getCurrentItem() == 0) {
txtViewTitle.setText("Week One, Monday");
}
if (vp.getCurrentItem() == 1) {
txtViewTitle.setText("Week One, Wednesday");
}
btnNext.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
MoveNext();
}
});
btnPrev.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
MovePrevious();
}
});
}
public void MoveNext() {
//it doesn't matter if you're already in the last item
vp.setCurrentItem(vp.getCurrentItem() + 1);
}
public void MovePrevious() {
//it doesn't matter if you're already in the first item
vp.setCurrentItem(vp.getCurrentItem() - 1);
}
private void addPages(NonSwipeableViewPager pager) {
MyFragPagerAdapter adapter = new MyFragPagerAdapter(getSupportFragmentManager());
Intent intent = getIntent();
String workout = intent.getStringExtra("workout");
Bundle args = new Bundle();
args.putString("workout", workout);
Week1Mon week1MonFragment = new Week1Mon();
week1MonFragment.setArguments(args);
adapter.addPage(week1MonFragment);
Week1Wed week1WedFragment = new Week1Wed();
week1WedFragment.setArguments(args);
adapter.addPage(week1WedFragment);
Week1Fri week1Fri = new Week1Fri();
week1Fri.setArguments(args);
adapter.addPage(week1Fri);
Week2Mon week2MonFragment = new Week2Mon();
week2MonFragment.setArguments(args);
adapter.addPage(week2MonFragment);
Week2Wed week2WedFragment = new Week2Wed();
week2WedFragment.setArguments(args);
adapter.addPage(week2WedFragment);
Week2Fri week2Fri = new Week2Fri();
week2Fri.setArguments(args);
adapter.addPage(week2Fri);
pager.setAdapter(adapter);
}
}
The part I have tried:
if (vp.getCurrentItem() == 0) {
txtViewTitle.setText("Week One, Monday");
}
if (vp.getCurrentItem() == 1) {
txtViewTitle.setText("Week One, Wednesday");
}
This sets the textview to Week One, Monday. Unfortunately it doesn't change when the user hits the Next button. I'm also hoping theres a better way, as I don't want to "assume" that the current item is that day of the week, because every week is different. I also need to figure out how to set the current page when the app is opened, because it saves the position is shared pref and I have to load it in the class above, and somehow set the page to a current page (preferably by the title)
Here is MyFragPagerAdapter:
public class MyFragPagerAdapter extends FragmentPagerAdapter {
ArrayList<Fragment> pages = new ArrayList<>();
public MyFragPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return pages.get(position);
}
#Override
public int getCount() {
return pages.size();
}
public void addPage(Fragment f) {
pages.add(f);
}
#Override
public CharSequence getPageTitle(int position) {
return pages.get(position).toString();
}
}
Thanks for any help, let me know if you need to see more code!

You can use,
viewPager.addOnPageChangeListener(new OnPageChangeListener() {
public void onPageScrollStateChanged(int state) {}
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}
public void onPageSelected(int position) {
// Check if this is the page you want.
}});

Android Viewflow go to view with a button

I am trying to make a nice horizontal viewgroup with the ViewFlow class.
I want to combine it with buttons. For example, when I click button 2 I go to view 2 of the viewgroup. Is that possible? I currently got this:
public class HousingActivity extends BaseActivity implements OnClickListener {
ViewFlow viewFlow;
ListView listView;
HousingViewflowAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.housing_activity);
init();
}
private void init() {
viewFlow = (ViewFlow) findViewById(R.id.viewflow);
setOnClickListner(this, this, new int[] { R.id.housing_button1,
R.id.housing_button2, R.id.housing_button3,
R.id.housing_button4 });
adapter = new HousingViewflowAdapter(this);
viewFlow.setAdapter(adapter);
viewFlow.setOnViewSwitchListener(new ViewSwitchListener() {
#Override
public void onSwitched(View view, int position) {
}
});
listView = (ListView) findViewById(R.id.housing_view1_listview);
ArrayList<Community> communityList = new ArrayList<Community>();
// Some dummy data
for (int i = 0; i < 10; i++) {
communityList.add(new Community("Place " + new Random().nextInt(),
new Random().nextInt(), 000000000, ""));
}
listView.setAdapter(new MainListViewAdapter(this, 0, communityList));
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// viewFlow.onConfigurationChanged(newConfig);
}
#Override
public void onClick(View v) {
super.onClick(v);
switch (v.getId()) {
case R.id.housing_button1:
break;
case R.id.housing_button2:
break;
case R.id.housing_button3:
break;
case R.id.housing_button4:
break;
}
}
}
Thanks in advance.

You can look into:
viewFlow.setSelection(int position)

Ah ! I found it !
viewFlow.setAdapter(adapter,number);
The number being the page you want to show