Develop Reference

OnPageChangeListener in ViewPager adapter?

I have a regular ViewPager with an adapter:
public class MyDialogFragment extends DialogFragment {
private ViewPager viewPager;
private MyViewPagerAdapter myViewPagerAdapter;
private City city;
public static MyDialogFragment newInstance() {
MyDialogFragment fragment = new MyDialogFragment();
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_layout, container, false);
viewPager = (ViewPager) v.findViewById(R.id.viewPager);
city = Parcels.unwrap(getArguments().getParcelable("city"));
myViewPagerAdapter = new MyViewPagerAdapter(getContext());
viewPager.setAdapter(myViewPagerAdapter);
viewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
// Page changed
}
});
return v;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
public class MyViewPagerAdapter extends PagerAdapter {
private Context context;
private LayoutInflater layoutInflater;
public MyViewPagerAdapter(Context context) {
this.context = context;
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
layoutInflater = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = layoutInflater.inflate(R.layout.city_layout, container, false);
ImageView imageView = (ImageView) view.findViewById(R.id.cityImage);
Glide.with(context)
.load(city.getImage())
.into(imageView);
}
container.addView(view);
return view;
}
#Override
public int getCount() {
return city.size();
}
#Override
public boolean isViewFromObject(View view, Object obj) {
return view == ((View) obj);
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
}
}
As you can see, I have a page change listener set on my ViewPager. But I need to be able to notify the adapter when the page has changed so that I can modify the adapter's ImageView. How can I do this?

Add a method to your adapter class
public class MyViewPagerAdapter extends PagerAdapter {
...
public void pageChanged(int position) {
// Do something
}
...
}
After that in your OnPageChangeListener use that method
#Override
public void onPageSelected(int position) {
myViewPagerAdapter.pageChanged(position);
}

One approach is to create a data structure in your adapter to map the pager view to its position. A SparseArray is most efficient:
private SparseArray<View> pageMap = new SparseArray<>();
Then in the adapter's instantiateItem() method, add the view to the SparseArray:
public Object instantiateItem(ViewGroup container, int position) {
...
pageMap.put(position, view);
...
}
Now in your OnPageChangeListener you can do the following:
#Override
public void onPageSelected(int position) {
View view = adapter.getView(pos);
if (view != null) {
ImageView iv = (ImageView) view.findViewById(R.id.your_image_view);
// You now have the image view
}
}
Make sure you remove views from the SparseArray in the adapter's destroyItem() method:
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
pageMap.remove(position);
...
}

You can use the constructor with imagelist to pass and that automatically called on next page..In your code will be modified like :::
ArrayList imageList=new ArrayList<>();
imageList.add("ImagePath here");
myViewPagerAdapter = new MyViewPagerAdapter(getContext(),imageList);
viewPager.setAdapter(myViewPagerAdapter);
Then your adapter will be like ::
public class MyViewPagerAdapter extends PagerAdapter {
private Context context;
private ArrayList<String> imageList
private LayoutInflater layoutInflater;
public MyViewPagerAdapter(Context context,ArrayList<String> imageList) {
this.context = context;
this.imageList = imageList;
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
layoutInflater = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = layoutInflater.inflate(R.layout.city_layout, container, false);
ImageView imageView = (ImageView) view.findViewById(R.id.cityImage);
Glide.with(context)
.load(imageList.get(position)) // This will be changes like
.into(imageView);
}
container.addView(view);
return view;
}
#Override
public int getCount() {
return city.size();
}
#Override
public boolean isViewFromObject(View view, Object obj) {
return view == ((View) obj);
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
}
That done ..
After this, there are some suggestion that
- please use arraylist while using the viewpager ..
Now you just taking the parceble object from bundle..
you can do the same for the arraylist,
just receive the arraylist from the same bundle by passing the whole arraylist at once.
so you dont need to find the page change event..viewpager will automatically handle that..
Here's How to send & receiving the parceable arraylist
// while sending the list
Bundle bundle = new Bundle();
bundle.putParcelableArrayList("citylist", new ArrayList<City>());
// while receiving the list
ArrayList<City> citylist = getIntent().getParcelableArrayListExtra("citylist");
After this just get the all image and add in the imagelist array
for (int i = 0; i < citylist.size(); i++) {
imageList.add(citylist.get(i).getImage());
}
And pass this imageList in
myViewPagerAdapter = new MyViewPagerAdapter(getContext(),imageList);
viewPager.setAdapter(myViewPagerAdapter);
Tell me if needed more assitance.

ViewPager Is Not Scrolling Smoothly

i implemented a viewpager in my activity that on scroll, loads a set of data to an adapter and display them in a list view. everything is working fine, but i cant seem to find out how to make it more efficient because when scrolling, the view freezes but for example in the GMAIL app when scrolling between Emails the scrolling is so smooth.
Below is the code i am using:
Activity:
in oncreate
pageradapter adapter2 = new pageradapter(this, ArrayOfItems); //ArrayOfItems is an Array containing the data that will be displayed
ViewPager myPager = (ViewPager) findViewById(R.id.mypanelpager);
myPager.setAdapter(adapter2);
pagechangelistener pageListener = new pagechangelistener();
myPager.setOnPageChangeListener(pageListener);
pageradapter:
public pageradapter(Activity act, ArrayList <List<Item>>Arrayitems) {
this.Arrayitems = Arrayitems;
activity = act;
}
public int getCount() {
return Arrayitems.size();
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
List<Item> item = Arrayitems.get(position);
ListView view = new ListView(activity);
taskdetailsarrayadaptertest adapter = new taskdetailsarrayadaptertest(activity, item);
view.setAdapter(adapter);
view.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));
((ViewPager) container).addView(view, 0);
return view;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
((ViewPager) container).removeView((View) object);
}
#Override
public boolean isViewFromObject(View arg0, Object arg1) {
return arg0 == ((View) arg1);
}
#Override
public Parcelable saveState() {
return null;
}
pagechangelistener:
#Override
public void onPageSelected(int position)
{
currentPage = position;
int positionTemp = position + 1;
}
public final int getCurrentPage() {
return currentPage;
}

First you need to use holders like this.
in your ViewPager:
class Holder{
ListView listView;
Adapter adapter;
}
private ArrayList<Holder> mHolders;
//init holders
#Override
public Object instantiateItem(ViewGroup collection, int position) {
Holder holder = mHolders.get(position);
holder.listView.setAdapter(holder.adapter);
collection.addView(holder.listView);
return holder.listView;
}
Second try async loading data in listview

set myPager.setOffscreenPageLimit(1);

Pager adapter with private methods without fragments in android

Is it possible to user View pager without fragments. I google it, and all examples use fragments for view pager. I want to pager load only one item from my list, so I want to ask is it possible. Here is my code for main activity, and I want to use UpdateDisplay for viewpager. Any suggestions.
public class MainActivity extends Activity implements OnClickListener{
private Button prev, next;
private TextView tv;
private int number = 0;
private ArrayList<Integer> numbers;
private ViewPager pager;
private MyPagerAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
prev = (Button) findViewById(R.id.prevButton);
prev.setOnClickListener(this);
next = (Button) findViewById(R.id.nextButton);
next.setOnClickListener(this);
numbers = new ArrayList<Integer>();
for (int i=0;i<5;i++){
numbers.add(i);
Log.i("Sljedece elemente dodaje u listu", String.valueOf(i));
}
tv = (TextView) findViewById(R.id.rezultatTextView);
pager = (ViewPager) findViewById(R.id.pager);
adapter = new MyPagerAdapter();
pager.setAdapter(adapter);
updateDIsplay(number);
}
#Override
public void onClick(View v) {
switch(v.getId()){
case R.id.prevButton:
number--;
if (number==-1){
number = 4;
}
updateDIsplay(number);
break;
case R.id.nextButton:
number++;
if (number==5){
number = 0;
}
updateDIsplay(number);
break;
}
}
private void updateDIsplay(int z){
tv.setText(String.valueOf(numbers.get(z)));
}
private class MyPagerAdapter extends PagerAdapter{
#Override
public int getCount() {
return numbers.size();
}
#Override
public boolean isViewFromObject(View arg0, Object arg1) {
return false;
}
}
}

yes it possible. Use a PageAdapter. When instantiateItem is called, you can inflate/instantiate your view, and this to the container. E.g:
private class MyPagerAdapter extends PagerAdapter {
#Override
public Object instantiateItem(ViewGroup container, int position) {
TextView view = new TextView(PagerActivity.this);
view.setText("Item "+position);
view.setGravity(Gravity.CENTER);
view.setBackgroundColor(Color.argb(255, position * 50, position * 10, position * 50));
container.addView(view);
return view;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View)object);
}
#Override
public int getCount() {
return 5;
}
#Override
public boolean isViewFromObject(View view, Object object) {
return (view == object);
}
}

How to update currentview of viewPager?

I need to change the size of all views on toggle. I did it but the
textsize got changed only from 3rd view. The first and second got
unchanged. Please suggest to update all the views.
public class MainActivity extends Activity {
ViewPager viewPager;
public static ArrayList<NewsItem> newslist;
public static PagerAdapter adapter;
public static ProgressDialog progressDialog;
LayoutInflater inflater;
public static float fntSize=30;
private ToggleButton togButton1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
newslist = new ArrayList<NewsItem>();
adapter = new ViewPagerAdapter(getApplicationContext(), newslist);
viewPager = (ViewPager) findViewById(R.id.pager);
viewPager.setAdapter(adapter);
addMainButtonListener();
loadNews();
}
public void addMainButtonListener() {
togButton1 = (ToggleButton) findViewById(R.id.toggleButton1);
togButton1.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (isChecked) {
fntSize=50;
} else {
fntSize=30;
}
}
});
#Override
public boolean onCreateOptionsMenu(Menu menu) {
new MenuInflater(this).inflate(R.menu.activity_main, menu);
return (super.onCreateOptionsMenu(menu));
}
private void loadNews(){
progressDialog= ProgressDialog.show(this,"Progress Dialog Title Text","Process Description Text");
News news = new News(getApplicationContext());
news.execute();
viewPager.setCurrentItem(0);
}
}
And My ViewPager class is
public class ViewPagerAdapter extends PagerAdapter {
// Declare Variables
Context context;
ArrayList<NewsItem> newslist = new ArrayList<NewsItem>();
LayoutInflater inflater;
public TextView txtNewsDesc;
public ViewPagerAdapter(Context context, ArrayList<NewsItem> newslist) {
this.context = context;
this.newslist = newslist;
}
#Override
public int getCount() {
return this.newslist.size();
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == ((RelativeLayout) object);
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View itemView = inflater.inflate(R.layout.news_item, container,
false);
txtNewsDesc = (TextView) itemView.findViewById(R.id.news_desc);
NewsItem news = this.newslist.get(position);
txtNewsDesc.setTextSize(MainActivity.fntSize);
txtNewsDesc.setText(news.getDesc());
// Add viewpager_item.xml to ViewPager
Typeface typeFace = Typeface.createFromAsset(context.getAssets(), "fonts/preeti.ttf");
txtNewsDesc.setTypeface(typeFace);
((ViewPager) container).addView(itemView);
return itemView;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
// Remove viewpager_item.xml from ViewPager
((ViewPager) container).removeView((RelativeLayout) object);
}
}
I know the first is not changed since it is not reloaded but what about 2nd view? Please help to change the text size of all the views on toggle button click.

The ViewPager creates and retains another page beside the current one and that demonstrates why the second stay the same.
To achieve what you want you need to update the size manually when the toggle button clicked, you can keep a reference to the current view in the ViewPagerAdapter and create a method to return that view as follow
public TextView getCurrentView(){
return txtNewsDesc;
}
Then in addMainButtonListener method get the current view using the method you have created and update the text size
togButton1.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked)
{
if (isChecked) {
fntSize=50;
} else {
fntSize=30;
}
((ViewPagerAdapter)viewPager).getCurrentView().setTextSize(fntSize);
}

You should use
public int getItemPosition(Object object) {
return POSITION_NONE;
}
use setTag() in instantiateItem() and instead of called notifyDataSetChanged() use findViewWithTag() and update tour text size.
For see this and in this thread https://stackoverflow.com/a/8024557

i found solution
crerate interface RefreshFragment
public interface RefreshFragment{void refresh();}
in the fragment which is pager item implement RefreshFragment
and at the class where you create the pager adapter do the folowing
circlePageIndicator.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
((RefreshFragment) pagerAdapter.getItem(position)).refresh();
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
i hope this is your solution

How can i getCurrentView by position in a ViewPager?

I need getCurrentView by position in a ViewPager
This my ViewPagerAdapter
public class TutorialViewPagerAdapter extends ViewPagerAdapter {
private LayoutInflater mInflater;
private View view;
private List<Integer> views;
public TutorialViewPagerAdapter(Activity act, List<Integer> views) {
super(act, null);
this.views = views;
this.mInflater = LayoutInflater.from(this.activity);
}
#Override
public void destroyItem(View container, int arg1, Object view) {
((ViewPager) container).removeView((View) view);
}
#Override
public int getCount() {
return views.size();
}
#Override
public Object instantiateItem(ViewGroup collection, int position) {
int viewId = (Integer) views.get(position);
this.view = mInflater.inflate(viewId, null);
((ViewPager) collection).addView(view);
return view;
}
}
And this is my activity
public class Tutorial extends FragmentActivity implements
ViewPager.OnPageChangeListener {
private List<Integer> views;
private TutorialViewPagerAdapter viewPagerAdapter;
private ViewPager viewPager;
private CirclePageIndicator circlePageIndicator;
private int currentViewId;
private View currentView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.tutorial);
init();
}
private void init() {
views = new ArrayList<Integer>();
views.add(R.layout.tutorial_step_one);
views.add(R.layout.tutorial_step_two);
views.add(R.layout.tutorial_step_three);
views.add(R.layout.tutorial_step_four);
views.add(R.layout.tutorial_step_five);
viewPagerAdapter = new TutorialViewPagerAdapter(this, views);
viewPager = (ViewPager) findViewById(R.id.steps_view_pager);
circlePageIndicator = (CirclePageIndicator) findViewById(R.id.steps_indicator);
viewPager.setAdapter(viewPagerAdapter);
viewPager.setCurrentItem(0, false);
circlePageIndicator.setViewPager(viewPager);
circlePageIndicator.setCentered(true);
circlePageIndicator.setPadding(20, 20, 20, 20);
circlePageIndicator.notifyDataSetChanged();
circlePageIndicator.setCurrentItem(0);
viewPager.setOnPageChangeListener(this);
}
#Override
public void onPageScrollStateChanged(int state) {
int currentPosition = viewPager.getCurrentItem();
circlePageIndicator.setCurrentItem(currentPosition);
enableStep(currentPosition);
}
private void enableStep(int currentPosition) {
/*viewPagerAdapter.getItemPosition(object)
currentView = viewPager.getChildAt(viewPager.getRootView());
Log.d("DEBUG", currentView.toString() + " CURRENT VIEW");*/
}
#Override
public void onPageScrolled(int position, float positionOffset,
int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
}
}

You could add all your created views in instantiateItem to an ArrayList<View> and then make a public method for getting a view from the ArrayList with get(position). But be carefully, as soon the Activity is finished the views could be null

Instead of ViewPagerAdapter you can use FragmentPagerAdapter which will have getItem(int position) method by using which you can easily access view.
You can take a look at this post : Android Return back to same fragment after click on goto first fragment in view pager
Hope this help!!

It's moot point. What exactly You need? Current view or view by position. Imho it is different things.
Current view:
currentView = viewPager.getCurrentItem();
Or view by index (you pass wrong parameter - should be int):
currentView = viewPager.getChildAt(currentPosition);