Develop Reference

Tab Layout not showing fragments

I have a fragment named "Notification fragment" in which I want to show another fragment named "Watching Fragment" using Tab layout . When I run the app, the tab layout bar is visible but the fragments are not visible.
My Fragment inside which other fragments are to be shown (Notifications Fragment)
public class NotificationsFragment extends Fragment{
GridView listv;
FragmentAdapter fragmentAdapter;
private NotificationsViewModel notificationsViewModel;
private FragmentNotificationsBinding binding;
public View onCreateView(#NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
notificationsViewModel =
new ViewModelProvider(this).get(NotificationsViewModel.class);
binding = FragmentNotificationsBinding.inflate(inflater, container, false);
View root = binding.getRoot();
TabLayout tabLayout = root.findViewById(R.id.tabLayout);
ViewPager vp = root.findViewById(R.id.vp2);
fragmentAdapter = new FragmentAdapter(getChildFragmentManager() , tabLayout.getTabCount());
vp.setAdapter(fragmentAdapter);
tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
vp.setCurrentItem(tab.getPosition());
if(tab.getPosition() == 0 || tab.getPosition() == 1 || tab.getPosition() == 2)
fragmentAdapter.notifyDataSetChanged();
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
vp.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
return root; }
My First Fragment (Watching Fragment)
public class WatchingFragment extends Fragment {
ArrayList<String> list = new ArrayList<String>();
GridView gridv1;
private WatchingViewModel mViewModel;
public static WatchingFragment newInstance() {
return new WatchingFragment();
}
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container,
#Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.watching_fragment, container, false);
gridv1 = view.findViewById(R.id.gridv1);
Intent intent = getActivity().getIntent();
String animename = intent.getStringExtra("nameanime");
list.add(animename);
loadData2();
saveData2();
ListNewAdapter adapter = new ListNewAdapter(getContext(), R.layout.watch_list, list);
gridv1.setAdapter(adapter);
gridv1.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
#Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
list.remove(position);
adapter.notifyDataSetChanged();
saveData2();
return true;
}
});
return view;
}
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mViewModel = new ViewModelProvider(this).get(WatchingViewModel.class);
// TODO: Use the ViewModel
}
private void saveData2() {
SharedPreferences sp = getActivity().getSharedPreferences("shared preferences", MODE_PRIVATE);
SharedPreferences.Editor ed = sp.edit();
Gson gson = new Gson();
String json = gson.toJson(list);
ed.putString("anime list", json);
ed.apply();
}
private void loadData2() {
SharedPreferences sp = getActivity().getSharedPreferences("shared preferences", MODE_PRIVATE);
Gson gson = new Gson();
String json = sp.getString("anime list", "");
Type type = new TypeToken<ArrayList<String>>() {}.getType();
list = gson.fromJson(json , type);
if (list == null) {
list = new ArrayList<String>();
}
}
}
My View pager adapter
public class FragmentAdapter extends FragmentPagerAdapter {
int tabcount;
public FragmentAdapter(#NonNull #NotNull FragmentManager fm, int behavior) {
super(fm, behavior);
tabcount = behavior;
}
#NonNull
#NotNull
#Override
public Fragment getItem(int position) {
switch (position){
case 0: return new WatchingFragment();
case 1: return new CompletedFragment();
case 2: return new WantToWatchFragment();
default: return null;
}
}
#Override
public int getCount() {
return 0;
}
}
Notifications Fragment Layout
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.notifications.NotificationsFragment">
<com.google.android.material.tabs.TabLayout
android:id="#+id/tabLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Watching" />
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Completed" />
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Want To Watch" />
</com.google.android.material.tabs.TabLayout>
<androidx.viewpager.widget.ViewPager
android:id="#+id/vp2"
android:name="com.example.animeguide.ui.notifications.NotificationsFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/tabLayout" />
</androidx.constraintlayout.widget.ConstraintLayout>
Watching Fragment Layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".ui.notifications.FragmentsInsideList.watching.WatchingFragment">
<TextView
android:id="#+id/textView4"
android:layout_width="184dp"
android:layout_height="58dp"
android:text="hello world"
android:textSize="34sp" />
<GridView
android:id="#+id/gridv1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:numColumns="2" />
</LinearLayout>

In order for the Adapter to know how many pages it has, you need to override getCount method. You did override it, but used 0 as the number of pages, thus having no pages.
In your FragmentAdapter class, try changing this:
#Override
public int getCount() {
return 0;
}
To this:
#Override
public int getCount() {
return tabcount;
}

Replace fragmentA with fragmentB issue

I have a image in the main activity and when this image is clicked i want to show the fragmentA that has a list view.
When a item of this listView is clicked i want to replace the fragmentA by the fragmentB that has a textview, and I want to show in this textview the text associated to the clicked list item.
So in main activity I have this:
public class MainActivity extends AppCompatActivity implements Listener{
private ImageView img;
private String text;
FragmentManager fragmentManager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fragmentManager = getFragmentManager();
img = (ImageView) findViewById(R.id.imageView);
}
public void AddFragmentA(View view) {
FragmentA fragmentA = new FragmentA();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.add(R.id.containerFragmentA, new FragmentA(), "fragA");
transaction.commit();
}
public void AddFragmentB() {
FragmentB fragment = new FragmentB();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.add(R.id.containerFragmentB, new FragmentA(), "fragB");
transaction.commit();
}
#Override
public void addText(String text) {
this.text = text;
Toast.makeText(this, "Text received in Activity:" +text, Toast.LENGTH_SHORT).show();
sendDataToFragmentB();
}
public void sendDataToFragmentB(){
FragmentB fragmentB = (FragmentB) fragmentManager.findFragmentByTag("fragB");
fragmentB.addText(text);
}
}
Note: The toast in addText() appears with the correct text at this point, so the text of the list view is received in Activity with success.
Question: Now how to replace fragmentA with fragmentB and show the textview with the received text in the activity instead of showing the listview of the fragmentA?
Below is all the complete example.
FragmentA class:
public class FragmentA extends Fragment{
private ListView listItems;
private String[] items = {
"item1",
"item2",
"item3",
"item4"
};
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment, container, false);
return view;
}
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
listItems = (ListView) getView().findViewById(R.id.listviewInFragment);
ArrayAdapter<String> adapter =
new ArrayAdapter<String>(getActivity().getApplicationContext(),
android.R.layout.simple_list_item_1, android.R.id.text1, items);
listItems.setAdapter(adapter);
listItems.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
int positionCode = i;
String clickedValue = (String) adapterView.getItemAtPosition(i);
Listener listener = (Listener) getActivity();
listener.addText(clickedValue);
}
});
}
}
FramentB:
public class FragmentB extends Fragment {
private TextView tv;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_b, container, false);
tv = (TextView) getView().findViewById(R.id.textView);
return view;
}
public void addText(String text) {
String result = text;
tv.setText(result);
}
}
main activity xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="#+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="#drawable/image"
android:onClick="AddFragmentA"
tools:layout_editor_absoluteX="0dp"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginBottom="8dp" />
<FrameLayout
android:id="#+id/containerFragmentA"
android:layout_width="0dp"
android:layout_height="300dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintHorizontal_bias="0.0"
tools:layout_editor_absoluteY="1dp">
</FrameLayout>
<FrameLayout
android:id="#+id/containerFragmentB"
android:layout_width="0dp"
android:layout_height="300dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintHorizontal_bias="0.0"
tools:layout_editor_absoluteY="1dp">
</FrameLayout>
</android.support.constraint.ConstraintLayout>
fragment a 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"
android:background="#0ff">
<ListView
android:layout_width="368dp"
android:layout_height="495dp"
android:layout_marginLeft="8dp"
android:layout_marginStart="16dp"
android:id="#+id/listviewInFragment"/>
</android.support.constraint.ConstraintLayout>
fragment b 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"
android:background="#ff0">
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="300dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
/>
</android.support.constraint.ConstraintLayout>

This is how you will achieve the required task.
make chnages to your class accordingly below.
MainActivity.java
public class MainActivity extends AppCompatActivity implements FragmentA.ClickListener{
private Button button;
public static String EXTRA_STRING = "extraString";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button)findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
AddFragment(FragmentA.getInstance());
}
});
}
public void AddFragment(Fragment fragment) {
getSupportFragmentManager().beginTransaction().replace(R.id.containerFragmentA, fragment).commit();
}
#Override
public void onClick(String data) {
AddFragment(FragmentB.getInstance(data));
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:id="#+id/containerFragmentA"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
tools:layout_editor_absoluteY="1dp"/>
<Button
android:id="#+id/button"
style="#style/Widget.AppCompat.Button.Colored"
android:layout_margin="8dp"
android:layout_alignParentBottom="true"
android:text="Add Fragment B"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</RelativeLayout>
FragmentA.java
public class FragmentA extends Fragment {
private ListView listItems;
private String[] items = {"item1", "item2", "item3", "item4"};
private ClickListener clickListener;
public static FragmentA getInstance() {
return new FragmentA();
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
clickListener = (ClickListener)context;
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_a, container, false);
return view;
}
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
listItems = (ListView) getView().findViewById(R.id.listviewInFragment);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getContext(),android.R.layout.simple_list_item_1, items);
listItems.setAdapter(adapter);
listItems.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
String clickedValue = items[i];
clickListener.onClick(clickedValue);
}
});
}
public interface ClickListener{
void onClick(String data);
}
}
fragment_a.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">
<ListView
android:layout_width="368dp"
android:layout_height="495dp"
android:layout_marginLeft="8dp"
android:layout_marginStart="16dp"
android:id="#+id/listviewInFragment"/>
</android.support.constraint.ConstraintLayout>
FragmentB.java
public class FragmentB extends Fragment {
private TextView tv;
private String data;
public static FragmentB getInstance(String data){
Bundle bundle = new Bundle();
bundle.putString(MainActivity.EXTRA_STRING,data);
FragmentB fragmentB = new FragmentB();
fragmentB.setArguments(bundle);
return fragmentB;
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_b, container, false);
tv = view.findViewById(R.id.textView);
data = getArguments().getString(MainActivity.EXTRA_STRING);
addText(data);
return view;
}
public void addText(String text) {
String result = text;
tv.setText(result);
}
}
fragment_b.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_gravity="center"
android:gravity="center"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:gravity="center"
android:textSize="24dp"
android:textAppearance="#style/TextAppearance.AppCompat.Widget.PopupMenu.Header"
android:id="#+id/textView"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>

you are placing fragment A in below function instead of fragment B
public void AddFragmentB() {
FragmentB fragment = new FragmentB();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.add(R.id.containerFragmentB, new FragmentA(), "fragB");
transaction.commit();
}
it should be
public void AddFragmentB() {
FragmentB fragment = new FragmentB();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.replace(R.id.containerFragmentB, new FragmentB(), "fragB");
transaction.commit();
}
if you want to replace a fragment with another just use the same container
don't create separate (R.id.containerFragmentB, R.id.containerFragmentA) container.

You need to change your
public void AddFragmentA(View view) {
FragmentA fragmentA = new FragmentA();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.add(R.id.containerFragmentA, new FragmentA(), "fragA");
transaction.commit();
}
public void AddFragmentB() {
FragmentB fragment = new FragmentB();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.add(R.id.containerFragmentB, new FragmentA(), "fragB");
transaction.commit();
}
to
public void AddFragmentA(View view) {
FragmentA fragmentA = new FragmentA();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.add(R.id.container, fragmentA , "fragA");
transaction.commit();
}
public void AddFragmentB() {
FragmentB fragment = new FragmentB();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.add(R.id.container, fragment, "fragB");
transaction.commit();
}
and activity_main.xml should be
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="#+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="#drawable/image"
android:onClick="AddFragmentList"
tools:layout_editor_absoluteX="0dp"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginBottom="8dp" />
<FrameLayout
android:id="#+id/container"
android:layout_width="0dp"
android:layout_height="300dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintHorizontal_bias="0.0"
tools:layout_editor_absoluteY="1dp">
</FrameLayout>
</android.support.constraint.ConstraintLayout>
EDIT
listItems.setAdapter(adapter);
listItems.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
int positionCode = i;
String clickedValue = (String) adapterView.getItemAtPosition(i);
Listener listener = (Listener) getActivity();
listener.addText(clickedValue);
}
});
Listener
public interface IScanner {
void addText(String Text);
}
MainActivity
public class MainActivity extends AppCompatActivity implements Listener{
private ImageView img;
private String text;
FragmentManager fragmentManager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fragmentManager = getFragmentManager();
img = (ImageView) findViewById(R.id.imageView);
}
public void AddFragmentA(View view) {
FragmentA fragmentA = new FragmentA();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.add(R.id.containerFragmentA, new FragmentA(), "fragA");
transaction.commit();
}
#Override
public void addText(String text) {
this.text = text;
Toast.makeText(this, "Text received in Activity:" +text, Toast.LENGTH_SHORT).show();
sendDataToFragmentB(text);
}
public void sendDataToFragmentB(String clickedValue){
Bundle b = new Bundle();
b.putString("clickedValue", clickedValue);
FragmentB fragment = new FragmentB();
fragment.setArguments(b);
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.add(R.id.containerFragmentB, new FragmentA(), "fragB");
transaction.commit();
}
}
FragmentB
public class FragmentB extends Fragment {
private TextView tv;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_b, container, false);
tv = (TextView) getView().findViewById(R.id.textView);
return view;
}
Bundle bundle = this.getArguments();
if (bundle != null) {
String text = bundle.getString("clickedValue", "");
}
}
This will solve your problem

ViewPager not visible inside Activity Layout

I'm working on an Application which contains a PageViewer inside a Layout.
But if i start it, the PageViewer isn't visible. (looks leight layout_height=0)
I never used a PageViewer inside other layouts, so maybe it isn't designed to be part of something?
Layout file (shortened,activity_tricks.xml):
<linearLayout>
<TableRow>
....
</TableRow>
<TableRow
android:layout_width="match_parent"
android:layout_height="wrapt_content">
<android.support.v4.view.ViewPager
android:id="#+id/Activity_Trick_viewPager"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_margin="6dip" />
</TableRow>
<TableRow>
.
.
.
Trick_Fragment_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/trick_fragment_textView_1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Medium Text"
android:textAppearance="?android:attr/textAppearanceMedium" />
</RelativeLayout>
Activity:
public class TrickActivity extends FragmentActivity {
private ViewPager mViewPager;
private TrickActivityPageAdapter mPageAdapter;
public static final int FRAMES = 3;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tricks);
mPageAdapter= new TrickActivityPageAdapter(getSupportFragmentManager(),frames);
mViewPager=(ViewPager)findViewById(R.id.Activity_Trick_viewPager);
mViewPager.setAdapter(mPageAdapter);
//... do other stuff.. //
}
}
public class TrickActivityPageAdapter extends FragmentPagerAdapter {
private int frames;
public TrickActivityPageAdapter(FragmentManager fm, int frames) {
super(fm);
this.frames = frames;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return TrickFragment.init("F 1");
case 1:
return TrickFragment
.init("F 2");
case 2:
return TrickFragment.init("f3");
default:
return TrickFragment.init("default");
}
}
#Override
public int getCount() {
return frames;
}
}
public class TrickFragment extends Fragment {
public static final String EXTRA_MESSAGE = "EXTRA_MESSAGE";
public static Fragment init(String string) {
TrickFragment f = new TrickFragment();
Bundle bdl = new Bundle();
bdl.putString(EXTRA_MESSAGE, string);
f.setArguments(bdl);
return f;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
String message = getArguments().getString(EXTRA_MESSAGE);
View v = inflater.inflate(R.layout.trick_fragment_layout, container, false);
TextView tv = (TextView)v.findViewById(R.id.trick_fragment_textView_1);
tv.setText(message);
return v;
}

ViewPagers and PagerAdapters

I am new to Android and am trying a sample application for showing ViewPagers in a Master-Detail Flow using custom PagerAdapters and FragmentStatePagerAdapters. My application has a list of dummy items managed by a SQLiteDatabase which contain a title String, a description String, a Boolean like status, and a list of images (I plan to implement them as downloading from String urls but presently I'm just trying with a single image resource). I am having two problems in the Detail View.
My intention is to use a ViewPager with a FragmentStatePagerAdapter to show the detail view, which consists of a ViewPager with a custom PagerAdapter for showing the list of images, TextView for title and description, a ToggleButton for the like status and a delete button for deleting items from the list.
Issues:
The ViewPager with the custom PagerAdapter does not display the image. It occupies the expected space and swipes performed on it also behave as expected. Only the image is not visible.
[RESOLVED] On using the delete button, I am able to delete the item from the database, and also update the Master View accordingly, but I am not able to update the Detail View, and the app crashes.
Here is my code:
Code that calls ItemDetailActivity.java
#Override
public void onClick(View v) {
Intent detailIntent = new Intent(getContext(), ItemDetailActivity.class);
detailIntent.putExtra(ItemDetailFragment.ARG_LIST_POSITION, holder.position);
getContext().startActivity(detailIntent);
}
ItemDetailActivity.java
public class ItemDetailActivity extends FragmentActivity {
static ItemDetailPagerAdapter idpa;
static ViewPager detailPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_item_detail);
idpa = new ItemDetailPagerAdapter(getSupportFragmentManager());
// Show the Up button in the action bar.
getActionBar().setDisplayHomeAsUpEnabled(true);
detailPager = (ViewPager) findViewById(R.id.item_detail_container);
detailPager.setAdapter(idpa);
detailPager.setCurrentItem(getIntent().getIntExtra(ItemDetailFragment.ARG_LIST_POSITION, 0));
}
}
activity_item_detail.xml
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/item_detail_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.trial.piclist.ItemDetailActivity"
tools:ignore="MergeRootFrame" />
ItemDetailFragment.java
public class ItemDetailFragment extends Fragment {
public static final String ARG_ITEM_ID = "item_id";
public static final String ARG_LIST_POSITION = "list_index";
public static final String ARG_TWO_PANE = "is_two_pane";
int position = -1;
long id = -1;
boolean twoPane = false;
ViewPager pager;
private PicItem mItem;
public ItemDetailFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
twoPane = getArguments().getBoolean(ARG_TWO_PANE, false);
position = getArguments().getInt(ARG_LIST_POSITION, -1);
id = getArguments().getLong(ARG_ITEM_ID, -1);
if (id == -1)
id = ItemListFragment.getIdByPosition(position);
setmItem(id);
}
public void setmItem(long id) {
if (id >= 0) {
try {
ItemListActivity.lds.open();
mItem = ItemListActivity.lds.getById(id);
ItemListActivity.lds.close();
} catch (Exception e) {
System.out.println(e.getMessage());
}
if (mItem != null) {
List<String> pics = new ArrayList<String>();
pics.add("1");
pics.add("2");
pics.add("3");
pics.add("4");
pics.add("5");
mItem.setPics(pics);
}
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_item_detail,
container, false);
DetailViewHolder holder = new DetailViewHolder();
pager = (ViewPager) rootView.findViewById(R.id.pager);
ImagePagerAdapter adapter = new ImagePagerAdapter(mItem, getActivity(),
inflater, position);
pager.setAdapter(adapter);
holder.position = getArguments().getInt(ARG_LIST_POSITION);
holder.ttv = (TextView) rootView.findViewById(R.id.item_title);
holder.dtv = (TextView) rootView.findViewById(R.id.item_detail);
holder.likeButton = (ToggleButton) rootView
.findViewById(R.id.item_like);
holder.deleteButton = (Button) rootView.findViewById(R.id.item_delete);
rootView.setTag(holder);
if (mItem != null) {
holder.ttv.setText(mItem.getTitle());
holder.dtv.setText(mItem.getDescription());
holder.likeButton.setChecked(mItem.getIsLiked());
holder.likeButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
ItemListActivity.lds.open();
ItemListActivity.lds.toggleLike(mItem.getId());
mItem.toggleIsLiked();
ItemListActivity.lds.close();
ItemListFragment.listDisplayHelper.toggleLiked(position);
}
});
holder.deleteButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
ItemListActivity.lds.open();
ItemListActivity.lds.removeItem(mItem.getId());
ItemListActivity.lds.close();
ItemListFragment.listDisplayHelper.remove(position);
ItemListActivity.idpa.notifyDataSetChanged();
// What do I do so that the FragmentStatePagerAdapter is
// updated and the viewpager shows the next item.
}
});
}
return rootView;
}
static private class DetailViewHolder {
TextView ttv;
TextView dtv;
ToggleButton likeButton;
Button deleteButton;
int position;
}
}
fragment_item_detail.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="16dp"
tools:context="com.trial.piclist.ItemDetailFragment" >
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="200dip">
</android.support.v4.view.ViewPager>
<TableRow
android:id="#+id/tableRow1"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<TextView
android:id="#+id/item_title"
style="?android:attr/textAppearanceLarge"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello"
android:textIsSelectable="true" />
<Space
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_weight="1" />
<include
android:layout_width="wrap_content"
android:layout_height="wrap_content"
layout="#layout/controls_layout" />
</TableRow>
<ScrollView
android:id="#+id/descScrollView"
android:layout_width="match_parent"
android:layout_height="0dip"
android:layout_weight="1" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="#+id/item_detail"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello" />
</LinearLayout>
</ScrollView>
</LinearLayout>
controls_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<ToggleButton
android:id="#+id/item_like"
android:layout_width="30dip"
android:layout_height="30dip"
android:layout_gravity="right"
android:background="#android:drawable/btn_star"
android:gravity="center"
android:text="#string/like_list_item"
android:textOff="#string/empty_text"
android:textOn="#string/empty_text" />
<Button
android:id="#+id/item_delete"
style="?android:attr/buttonStyleSmall"
android:layout_width="30dip"
android:layout_height="30dip"
android:background="#android:drawable/ic_menu_delete"
android:text="#string/empty_text" />
</LinearLayout>
Custom PagerAdapter
ImagePagerAdapter.java
public class ImagePagerAdapter extends PagerAdapter {
LayoutInflater inflater;
List<View> layouts = new ArrayList<>(5);
// Constructors.
#Override
public Object instantiateItem(ViewGroup container, int position) {
if (layouts.get(position) != null) {
return layouts.get(position);
}
View layout = inflater.inflate(R.layout.detail_image,
((ViewPager) container), true);
try {
ImageView loadSpace = (ImageView) layout
.findViewById(R.id.detail_image_view);
loadSpace.setBackgroundColor(0x000000);
loadSpace.setImageResource(R.drawable.light_grey_background);
loadSpace.setAdjustViewBounds(true);
} catch (Exception e) {
System.out.println(e.getMessage());
}
layout.setTag(images.get(position));
layouts.set(position, layout);
return layout;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
}
#Override
public int getCount() {
return 5;
}
#Override
public boolean isViewFromObject(View view, Object object) {
return (((View) object).findViewById((view.getId())) != null);
}
}
FragmentPagerAdapter
ItemDetailPagerAdapter.java
public class ItemDetailPagerAdapter extends FragmentStatePagerAdapter {
public ItemDetailPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
Fragment fragment = new ItemDetailFragment();
Bundle args = new Bundle();
args.putLong(ItemDetailFragment.ARG_ITEM_ID, ItemListFragment.getIdByPosition(position));
args.putInt(ItemDetailFragment.ARG_LIST_POSITION, position);
args.putBoolean(ItemDetailFragment.ARG_TWO_PANE, ItemListActivity.mTwoPane);
fragment.setArguments(args);
return fragment;
}
#Override
public int getCount() {
openDatabase();
int c = database.getCount();
closeDatabase();
return c;
}
#Override
public int getItemPosition(Object object) {
long mId = ((ItemDetailFragment) object).getmId();
int pos = POSITION_NONE;
openDatabase();
if (database.contains(mId)) {
pos = database.getPositionById(mId);
}
closeDatabase();
return pos;
}
}
Any help is much appreciated. Thanks :)

In your ItemDetailFragment, remove the viewpager from the holder, it should be directly into the returned view, something like this:
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_item_detail,
container, false);
pager = (ViewPager) rootView.findViewById(R.id.pager);
ImagePagerAdapter adapter = new ImagePagerAdapter(mItem, getActivity(),inflater, position);
pager.setAdapter(adapter);
return rootView;
}
and the ViewHolder pattern should be applied inside your PagerAdapter.

In ImagePagerAdapter.java, correct the isViewFromObject method -
#Override
public boolean isViewFromObject(View view, Object object) {
return (view == (View) object);
}
This will correct the issue of the ImageView.
In ItemDetailPagerAdapter.java, override the getItemPosition method -
#Override
public int getItemPosition(Object object) {
int ret = POSITION_NONE;
long id = ((ItemDetailFragment) object).getId();
openDatabase();
if (databaseContains(id)) {
ret = positionInDatabase(id);
}
closeDatabase();
return ret;
}
On deleting call the FragmentStatePagerAdapter.NotifyDataSetChanged() method. This will make the Adapter update itself on deleting.
Although, the FragmentStatePagerAdapter uses a list of Fragments and of stored states to implement the adapter. That is also causing trouble. To remove that, implement your own list of Fragments.

Get view for button click on the Fragment of the ViewPager

I have successfully set up the a FragmentActivity with FragementPagerAdapter associated with ViewPager to implement two tabbed application .
One of the Tabs namely "Wave" has a text view and a button . All I want is call textview.setText method via the onClick method of button described by its xml attribute .
I do not know where should I initialize my TextView or Button , how can I get the context of Wave tab and where should I write onclick method-
public class InformationShow extends FragmentActivity {
XMLdata dataObject;
ViewPager viewPager;
PagerAdapter adpt;
Fragment temp;
TextView tv;
Button bt;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_main);
viewPager=(ViewPager)findViewById(R.id.pager);
adpt = new PagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(adpt);
// temp=adpt.fg.findFragmentById((int)adpt.getItemId(1));
tv=(TextView)findViewById(R.id.graphWaveTextView);
bt = (Button)findViewById(R.id.button1);
}
public void changeText(View v){
tv.setText("It worked ");
}
Adapter Class
public class PagerAdapter extends FragmentPagerAdapter {
int count = 2;
CharSequence namme[] = {"Temperature","Wave"};
XMLdata data;
FragmentManager fg;
public PagerAdapter(FragmentManager fragmentManager ){
super(fragmentManager);
this.fg = fragmentManager;
}
Context context;
#Override
public Fragment getItem(int arg0) {
switch (arg0){
case 0:{
TemperatureGraphFrag temp = new TemperatureGraphFrag();
return temp;
}
case 1:{WaveHeightGraphFrag wave = new WaveHeightGraphFrag();
return wave;
}
}
return null;
}
#Override
public int getCount() {
return 2;
}
#Override
public CharSequence getPageTitle(int position) {
return namme[position];
}
}
Fragments Class
public class TemperatureGraphFrag extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.graph_t, container, false);
return view;
}
}
public class WaveHeightGraphFrag extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.graph_sig_wave_height, container, false);
return view;
}
}
fragment_main XML implemented by FragmentActicity
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<android.support.v4.view.PagerTabStrip
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="top"
android:paddingBottom="10dp"
android:paddingTop="10dp"
android:textColor="#65C2C9"
android:scrollbarSize="5dp"/>
</android.support.v4.view.ViewPager>
Tab 2 Fragment XML graph_sig_wave_height
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
>
<TextView
android:id="#+id/graphWaveTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Small Text"
android:textAppearance="?android:attr/textAppearanceSmall"
android:layout_gravity="center"
/>
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
android:layout_gravity="center"
android:onClick="changeText"/>
</LinearLayout>
Tab 1 fragment layout XML graph_t
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:id="#+id/linearTemp"
>
<TextView
android:id="#+id/graphTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Medium Text"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_gravity="center"
/>
</LinearLayout>

Add the following method to your WaveHeightGraphFrag class:
#Override
public void onViewCreated(View view, Bundle savedInstanceState){
final TextView t = (TextView) view.findViewById(R.id.graphWaveTextView);
Button b = (Button) view.findViewById(R.id.button1);
b.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View v){
t.setText("It worked ");
}
});
}
This is what you want.