Develop Reference

Error sending data from one fragment to another fragment. ( Both fragments are hosted by one activity)

I am having troubling sending data from one fragment to another fragment. I was following the android guideline which tells me to create an interface to communicate with activity and fragments. I'm using the bottom navigation to switch over fragments.
Anyway, here's the error from android studio:
java.lang.NullPointerException: Attempt to invoke virtual method 'void com.example.makkhay.cameratranslate.Favorite.displayReceivedData(java.lang.String)' on a null object reference
at com.example.makkhay.cameratranslate.HomeActivity.sendData(HomeActivity.java:143)
at com.example.makkhay.cameratranslate.HomeFragment$2.onClick(HomeFragment.java:162)
at android.view.View.performClick(View.java:6256)
at android.view.View$PerformClick.run(View.java:24697)
at android.os.Handler.handleCallback(Handler.java:789)
For some reason, my fragments are always null even after initializing it. I tried initializing it both ways, onCreate method, and the sendData method, the instance always seems to be null. I think the main culprit might be the DrawerLayout. Since it is the parent xml and there is another xml called "app_bar_home.xml"; which is hosting the two fragments using bottom navigation, the newly created instances are always null
Here's my main activity which is holding two fragments
HomeActivity.java
public class HomeActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener,HomeFragment.SendMessage {
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
Fragment selectedFragment = null;
switch (item.getItemId()) {
case R.id.navigation_home:
selectedFragment = new HomeFragment();
break;
case R.id.navigation_favorite:
selectedFragment = new Favorite();
break;
}
getSupportFragmentManager().beginTransaction().replace(R.id.app_bar,
selectedFragment).commit();
return true;
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
//I added this if statement to keep the selected fragment when rotating the device
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction().replace(R.id.app_bar,
new HomeFragment()).commit();
}
}
#Override
public void sendData(String message) {
Favorite f = (Favorite) getSupportFragmentManager().findFragmentById(R.id.favFragment);
f.displayReceivedData(message);
}
}
Here's my xml for my activity
activity_home.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout 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:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
android:id="#+id/app_bar"
layout="#layout/app_bar_home"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.NavigationView
android:id="#+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="#layout/nav_header_home"
app:menu="#menu/activity_home_drawer" />
</android.support.v4.widget.DrawerLayout>
Here's the app_bar_home.xml which is also part of the activity
<?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:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".HomeActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"
>
<android.support.v7.widget.Toolbar
android:layout_width="match_parent"
android:layout_height="?actionBarSize"
app:layout_collapseMode="pin"
android:id="#+id/toolbar"
/>
</android.support.design.widget.AppBarLayout>
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigation"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="0dp"
android:layout_marginStart="0dp"
app:layout_constraintBottom_toBottomOf="parent"
android:background="#000"
app:itemIconTint="#color/color_selector"
app:itemTextColor="#color/color_selector"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="#menu/navigation" />
</android.support.constraint.ConstraintLayout>
Here's the fragment 1 from which I want to send the data to another fragment.
HomeFragment.java
public class HomeFragment extends Fragment implements View.OnClickListener{
SendMessage SM;
private Button clearButton, favButton, shareButton;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_home, container, false);
return v;
}
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
favButton = view.findViewById(R.id.favButton);
favButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
SM.sendData(" test");
}
});
}
interface SendMessage {
void sendData(String message);
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
try {
SM = (SendMessage) getActivity();
} catch (ClassCastException e) {
throw new ClassCastException("Error in retrieving data. Please try again");
}
}
}
HomeFragment.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:id="#+id/homeFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".HomeFragment"
>
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?actionBarSize"
app:layout_collapseMode="pin" />
</android.support.design.widget.AppBarLayout>
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="6dp"
android:layout_marginEnd="6dp"
android:layout_marginLeft="6dp"
android:layout_marginRight="6dp"
android:layout_marginStart="6dp"
android:layout_marginTop="56dp"
android:background="#drawable/card_shadow"
android:divider="?android:dividerHorizontal"
android:paddingTop="6dp"
android:paddingBottom="6dp"
android:showDividers="middle">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:paddingBottom="16dp"
android:gravity="right"
android:orientation="vertical">
<Button
android:id="#+id/favButton"
android:layout_width="48dp"
android:layout_height="48dp"
android:layout_marginTop="4dp"
android:background="#drawable/ic_favorite_black_12dp"
/>
</LinearLayout>
</LinearLayout>
</android.support.constraint.ConstraintLayout>
</android.support.constraint.ConstraintLayout>
Finally here's the 2nd fragment where I want to recieve the data
Favorite.java
public class Favorite extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_favorite, container, false);
favText = v.findViewById(R.id.tv_recycler_item_1);
return v;
}
protected void displayReceivedData(String message)
{
Toast.makeText(getContext(),"rec:" + message,Toast.LENGTH_SHORT).show();
}
}
fragment_favorite.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
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:id="#+id/favFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".Favorite">
<android.support.design.widget.AppBarLayout
android:id="#+id/app_bar_scrolling"
android:layout_width="match_parent"
android:layout_height="180dp"
android:fitsSystemWindows="true"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.design.widget.CollapsingToolbarLayout
android:id="#+id/collapsing_toolbar_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
app:contentScrim="?attr/colorPrimary"
app:layout_scrollFlags="scroll|exitUntilCollapsed">
<ImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:scaleType="centerCrop"
android:src="#drawable/bg_red" />
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="#style/Widget.AppCompat.PopupMenu.Overflow" />
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
>
<TextView
android:id="#+id/txtData"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="548dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#+id/recycler_view_recycler_view"
app:layout_constraintStart_toStartOf="parent" />
<android.support.v7.widget.RecyclerView
android:id="#+id/recycler_view_recycler_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="382dp"
android:layout_marginEnd="344dp"
android:layout_marginRight="344dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
</android.support.v7.widget.RecyclerView>
</android.support.constraint.ConstraintLayout>
</android.support.design.widget.CoordinatorLayout>
Let me know if you need more info. thanks in advance :)

you can pass data between fragment by putting as argument in bundle like following:
Fragment fragment = new Fragment();
Bundle bundle = new Bundle();
bundle.putInt(key, value);
fragment.setArguments(bundle);
For retrieving you can do following
Bundle bundle = this.getArguments();
if (bundle != null) {
int myInt = bundle.getInt(key);
}

On my view best way of communication is by using EventBus between Activity-fragment, fragment-fragment, Activity-Activty, very easy and less complicated
Here is an Example
Create a model of what you want to share, so here is model for sending string declare the string variable use constructor and getter for setting and getting message
public MessageEvent(String Message)
{
this.msg=msg;
}
public String getMsg() {
return msg;}
Now in your fragment 1 post the message before that register eventbus on OnAttach and deregister it in OnDettach
EventBus.getDefault().post(new MessageEvent("My Message));
In Fragment 2 get the message in OnEvent Method(even in this fragment don't forget to register and deregister Event Bus)
#Subscribe
public void onEvent(MessageEvent event) {
this.msg=event.getMsg();
callTheMethodToDoYourOperation(msg);
}
This a basic example, but check about event bus before using this and moreover in both fragment you require to Register, deregister and subscribe onevent, and if this is one way communication let onEvent be empty
Hope this helps

The NullPointerException occurred because your Fragment is not initialized yet, so before interacting with is make sure you check is it initialized and visible or not.
if (f!= null && f.isVisible()) {
f.displayReceivedData(message);
}
You can also use Bundle to pass data between Fragment too.
Note: Before posting question understand the error and try to debug the root cause of the error. You'll definitely solve it on your own.
Happy coding :)

You are getting Null pointer on method where you receive data, that fragment instance is null. Favorite f is null.
Create one instance if that fragment and then call .replace

Bottomnavigationview hides when switching from a tab with collapsing toolbar

I have a MainActivity XML that contains a bottomNavigationView (bar) with 5 tabs. Each tab calls a different fragment. Switching from a fragment with a collapsing toolbar in its XML (labelled A in picture) to a fragment with a plain fragment (labelled B in picture) causes the bottomNavigationView (bar) to hide partially off the screen.
Is there a way of preventing this?
Screen with fragment containing collapsing toolbar.
Screen of another tab with a plain fragment.
Fragment Class containing code for collapsing toolbar
public class Profile extends Fragment {
public Profile() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
//setHasOptionsMenu(true);
View rootView = inflater.inflate(R.layout.fragment_profile, container, false);
Toolbar toolbar = rootView.findViewById(R.id.toolbar);
AppCompatActivity activity = (AppCompatActivity) getActivity();
activity.setSupportActionBar(toolbar);
activity.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
CollapsingToolbarLayout collapsingToolbar = rootView.findViewById(R.id.collapsing_toolbar);
collapsingToolbar.setTitle("test");
return rootView;
}
Corresponding xml containing collapsing toolbar code
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<android.support.v7.widget.RecyclerView
android:id="#+id/recycler"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="180dp"
android:theme="#style/ThemeOverlay.AppCompat.Dark">
<android.support.design.widget.CollapsingToolbarLayout
android:id="#+id/collapsing_toolbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
app:contentScrim="?attr/colorPrimary"
app:layout_scrollFlags="scroll|exitUntilCollapsed">
<ImageView
android:id="#+id/header"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/ani_dog_one"
android:contentDescription="whut"
android:fitsSystemWindows="true"
android:scaleType="centerCrop"
app:layout_collapseMode="parallax" />
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin" />
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
</android.support.design.widget.CoordinatorLayout>
Plain fragment class
public class Review extends Fragment {
public Review() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_review, container, false);
//setHasOptionsMenu(true);
return rootView;
}
#Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.search_bar_menu, menu);
super.onCreateOptionsMenu(menu, inflater);
}
XML for plain fragment class contains just a plain FrameLayout
MainActivity
public class MainActivity extends AppCompatActivity {
private Intent intent;
private android.support.v4.app.FragmentManager manager;
private android.support.v4.app.FragmentTransaction transaction;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
manager = getSupportFragmentManager();
transaction = manager.beginTransaction();
Discover discoverFragment = new Discover();
transaction.replace(R.id.container, discoverFragment, discoverFragment.getTag()).commit();
setupBottomNavigationView();
}
private void setupBottomNavigationView() {
BottomNavigationViewEx bottomNavigationViewEx = (BottomNavigationViewEx) findViewById(R.id.bottom_navigation);
BottomNavigationViewHelper.setupBottomNavigationView(bottomNavigationViewEx);
BottomNavigationViewHelper.enableNavigation(this, bottomNavigationViewEx);
}
public void goToOptions(MenuItem menu) {
intent = new Intent(this, Options.class);
overridePendingTransition(R.anim.left_in, R.anim.right_out);
startActivity(intent);
}
}
XML for MainActivity
<LinearLayout 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"
android:orientation="vertical"
tools:context="com.example.android.project_qwer.MainActivity">
<!-- main fragments goes here -->
<FrameLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1">
</FrameLayout>
<!-- bottom navigation view -->
<com.ittianyu.bottomnavigationviewex.BottomNavigationViewEx
android:id="#+id/bottom_navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:background="?android:attr/windowBackground"
app:menu="#menu/bottom_navigation_menu" >
</com.ittianyu.bottomnavigationviewex.BottomNavigationViewEx>
</LinearLayout>

Try to remove
android:fitsSystemWindows="true"
on your CollapsingToolbarLayout.

try
getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
when you switch to tab with collapsing toolbar and
getWindow().clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
when switch to another

Try to put
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
</android.support.design.widget.CoordinatorLayout>
as the root of all the other fragments you are loading from the BottomNavigationView.

If you use a custom toolbar in the profile fragment,you put this code to onCreateView method:
((AppCompatActivity)getActivity()).setSupportActionBar(toolbar);
I had the same problem and this was solved.

Remove android:fitsSystemWindows="true"
from root CoordinatorLayout.

Fragment not loading when selected from MaterialDrawer

I have an activity which has a MaterialDrawer created. The material Drawer code is as follows
SecondaryDrawerItem item1 = new SecondaryDrawerItem().withIdentifier(1).withName(R.string.drawer_item_home)
.withIcon(new IconicsDrawable(this)
.icon(GoogleMaterial.Icon.gmd_home)
.sizeRes(R.dimen.activity_horizontal_margin));
SecondaryDrawerItem item2 = new SecondaryDrawerItem().withIdentifier(2).withName(R.string.drawer_item_graph)
.withIcon(new IconicsDrawable(this)
.icon(GoogleMaterial.Icon.gmd_trending_up)
.sizeRes(R.dimen.activity_horizontal_margin));
SecondaryDrawerItem item3 = new SecondaryDrawerItem().withIdentifier(3).withName(R.string.drawer_item_map)
.withIcon(new IconicsDrawable(this)
.icon(GoogleMaterial.Icon.gmd_map)
.sizeRes(R.dimen.activity_horizontal_margin));
SecondaryDrawerItem item4 = new SecondaryDrawerItem().withIdentifier(4).withName(R.string.drawer_item_settings)
.withIcon(new IconicsDrawable(this)
.icon(GoogleMaterial.Icon.gmd_settings)
.sizeRes(R.dimen.activity_horizontal_margin))
.withSelectable(false);
new DrawerBuilder()
.withActivity(this)
.withToolbar(getToolbar())
.withSelectedItem(1)
.withAccountHeader(headerResult)
.withActionBarDrawerToggleAnimated(true)
.addDrawerItems(
item1,
item2,
item3,
new DividerDrawerItem(),
item4
)
.withOnDrawerItemClickListener(new Drawer.OnDrawerItemClickListener() {
#Override
public boolean onItemClick(View view, int position, IDrawerItem drawerItem) {
// do something with the clicked item :D
if (drawerItem != null) {
if (drawerItem.getIdentifier() == 1) {
getSupportFragmentManager().beginTransaction()
.replace(R.id.fragment, new WeatherFragment())
.commit();
}
else if (drawerItem.getIdentifier() == 2) {
getSupportFragmentManager().beginTransaction()
.replace(R.id.fragment, new GraphsFragment())
.commit();
}
else if (drawerItem.getIdentifier() == 3) {
getSupportFragmentManager().beginTransaction()
.replace(R.id.fragment, new MapsFragment())
.commit();
}
else if (drawerItem.getIdentifier() == 4) {
startActivity(new Intent(WeatherActivity.this, AboutActivity.class));
}
}
return false;
}
})
.build();
When my app starts, the default option selected is 1, ie. the activity automatically loads WeatherFragment when the App is started. The problem occurs when I click on the Second item in the list : Graphs Fragment. According to the code, it should have worked, but what it does is it retains the old fragment in view, and does not load the layout of the new Fragment.
Here is the Activity XML Layout:
<android.support.design.widget.CoordinatorLayout 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"
android:background="#color/colorPrimary"
tools:context="com.a5corp.weather.activity.WeatherActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.NoActionBar.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="#style/AppTheme.NoActionBar.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<include layout="#layout/content_weather" />
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
app:srcCompat="#drawable/ic_search_white_24dp" />
</android.support.design.widget.CoordinatorLayout>
content_weather.xml :
<fragment 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:id="#+id/fragment"
android:name="com.a5corp.weather.fragment.WeatherFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:layout="#layout/fragment_weather" />
Until now, what is clear is that WeatherActivity will always load fragment_weather (WeatherFragment) as such. But when I click on the GraphsFragment (second item), it does not load that layout
Here is my GraphsFragment code:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
Log.i("Loaded" , "Fragment"); //This Log info shows up in the Android Logger
rootView = inflater.inflate(R.layout.fragment_graphs, container, false);
return rootView;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MaterialDialog.Builder builder = new MaterialDialog.Builder(this.getActivity())
.title("Please Wait")
.content("Loading")
.progress(true , 0);
builder.build().show();
}
fragment_graphs.xml :
<android.support.v4.widget.SwipeRefreshLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="#+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="111dp"
android:text="Button"/>
<Switch
android:id="#+id/switch1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignStart="#+id/button2"
android:layout_below="#+id/button2"
android:layout_marginTop="40dp"
android:text="Switch"/>
</RelativeLayout>
</android.support.v4.widget.SwipeRefreshLayout>
The progress dialog shows as such, but the layout items like the button and the switch from GraphsFragment XML do not load.
How will I load the GraphsFragment when clicked from the Drawer, along with the layout inflated and the progress dialog shown

Turns out I only needed to add a FrameLayout instead of includeing the layout.
Here is the modified main XML file
<android.support.design.widget.CoordinatorLayout 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"
android:background="#color/colorPrimary"
tools:context="com.a5corp.weather.activity.WeatherActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/appBar"
android:theme="#style/AppTheme.NoActionBar.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="#style/AppTheme.NoActionBar.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/fragment"
android:paddingTop="?attr/actionBarSize"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.a5corp.weather.WeatherActivity"
tools:ignore="MergeRootFrame"
android:background="#color/colorPrimary" />
</android.support.design.widget.CoordinatorLayout>

Replacing NestedScrollView in Master/Detail Flow with a ListView

I am new to android and have little time to do an assignment, so I figured out I will use "Templates" like Master/Detail Flow to speed up my work. Maybe it wasn't the best decision, since I needed ages to understand given code and even now I still don't understand everything... But now it's too late to start from a scratch.
I have a list of recipes, when a recipe is clicked I can see details (done with the Master/Detail-Template). A recipe has a list of ingredients and a string with description how to prepare it. I wrote a custom adapter to show the list of ingredients in the details fragment and it didn't work at first. The reason was that the ListView I used was placed in the NestedScrollView in the "recipe_detail_activity.xml". This, as I found out, can not work, because both of them have scrolling mechanisms. I tried to replace NestedScrollView with a LinearLayout, as I thought it's only a simple container, but then the ingredients list is rendered at the top of the screen (instead of where the NestedScrollView once was) and the description is not rendered at all.
The way it works now: RecipeDetailActivity.java registers a fragment with recipe_detail_activity.xml as container and RecipeDetailFragment inflates recipe_detail.xml, which contains a ListView for ingredients and a TextView for the description.
I know, I'm obviously lacking of knowladge and should start with easy things, but my professor is pretty demanding... I would be very glad if someone could give me a hint.
recipe_activity_detail.xml:
<android.support.design.widget.CoordinatorLayout 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"
android:fitsSystemWindows="true"
tools:context="com.kalina.kochapp.RecipeDetailActivity"
tools:ignore="MergeRootFrame">
<android.support.design.widget.AppBarLayout
android:id="#+id/app_bar"
android:layout_width="match_parent"
android:layout_height="#dimen/app_bar_height"
android:fitsSystemWindows="true"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.design.widget.CollapsingToolbarLayout
android:id="#+id/toolbar_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
app:contentScrim="?attr/colorPrimary"
app:layout_scrollFlags="scroll|exitUntilCollapsed"
app:toolbarId="#+id/toolbar">
<android.support.v7.widget.Toolbar
android:id="#+id/detail_toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light" />
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v4.widget.NestedScrollView
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior" >
</android.support.v4.widget.NestedScrollView>
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical|start"
android:layout_margin="#dimen/fab_margin"
app:layout_anchor="#+id/recipe_detail_container"
app:layout_anchorGravity="top|end"
app:srcCompat="#android:drawable/stat_notify_chat" />
</android.support.design.widget.CoordinatorLayout>
recipe_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">
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/lv_recipe_ingredients"
style="?android:attr/textAppearanceLarge"
android:padding="16dp"
tools:context="com.kalina.kochapp.RecipeDetailFragment"/>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/recipe_instructions"
style="?android:attr/textAppearanceLarge"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp"
android:textIsSelectable="true"
tools:context="com.kalina.kochapp.RecipeDetailFragment" />
</LinearLayout>
RecipeDetailActivity.java:
protected void onCreate(Bundle savedInstanceState) {
[...]
if (savedInstanceState == null) {
// Create the detail fragment and add it to the activity
// using a fragment transaction.
Bundle arguments = new Bundle();
arguments.putString(RecipeDetailFragment.ARG_ITEM_ID,
getIntent().getStringExtra(RecipeDetailFragment.ARG_ITEM_ID));
RecipeDetailFragment fragment = new RecipeDetailFragment();
fragment.setArguments(arguments);
getSupportFragmentManager().beginTransaction()
.add(R.id.recipe_detail_container, fragment)
.commit();
}
}
RecipeDetailFragment.java:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.recipe_detail, container, false);
// Show the dummy content as text in a TextView.
if (mItem != null) {
((TextView) rootView.findViewById(R.id.recipe_instructions)).setText(mItem.instructions);
}
return rootView;
}
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
ingredients = (ListView)getView().findViewById(R.id.lv_recipe_ingredients);
IngredientsListAdapter ila = new IngredientsListAdapter(this.getContext(), mItem.ingredients);
ingredients.setAdapter(ila);
}

Ok, I fixed it by adding "android:fillViewport="true"" to my NestedScrollView. This way I can use a regular ListView inside of it. I don't know whether this solution is fancy, but it works.

Cannot scroll RecyclerView inside a Fragment?

I am having troubles integrating a RecyclerView (using cardviews for the rows) inside a fragment. For some reason I cannot scroll the card view? Please, any suggestions?
This is my app design:
This is my fragment code:
public class PageFragment2 extends Fragment {
public static final String ARG_PAGE2 = "ARG_PAGE";
private int mPage2;
public static PageFragment2 newInstance(int page) {
Bundle args = new Bundle();
args.putInt(ARG_PAGE2, page);
PageFragment2 fragment = new PageFragment2();
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mPage2 = getArguments().getInt(ARG_PAGE2);
Log.d("MainActivity", "onCreate" + mPage2);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_page2,container,false);
RecyclerView recList = (RecyclerView) view;
recList.setHasFixedSize(true);
LinearLayoutManager llm = new LinearLayoutManager(getActivity());
recList.setLayoutManager(llm);
ArrayList<String> names = new ArrayList<>();
names.add("Georgi Koemdzhiev");
names.add("Mariya Menova");
names.add("Simeon Simeonov");
names.add("Ivan Dqkov");
names.add("Dymityr Vasilev");
names.add("Petar Dimov");
CardAdapter adapter = new CardAdapter(names);
recList.setAdapter(adapter);
Log.d("MainActivity","onCreateView" + mPage2);
return view;
}
}
This is my fragment XML code:
<android.support.v7.widget.RecyclerView
android:id="#+id/cardList"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipToPadding="true"
xmlns:android="http://schemas.android.com/apk/res/android"/>
My activity_main layout:
<android.support.design.widget.CoordinatorLayout
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"
android:fitsSystemWindows="true"
tools:context="koemdzhiev.com.newtablayouttest.MainActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="#style/AppTheme.PopupOverlay"/>
<android.support.design.widget.TabLayout
android:id="#+id/sliding_tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<android.support.v4.view.ViewPager
android:id="#+id/viewpager"
android:layout_width="match_parent"
android:layout_height="0px"
android:layout_weight="1"
android:background="#android:color/white" />
</android.support.design.widget.AppBarLayout>
<include layout="#layout/content_main"/>

The Activity from the "Tabbed Activity" template, which contains the ViewPager which is containing your Fragment, uses an AppBarLayout.
This AppBarLayout is stealing the vertical movement, since it doesn't know there's a scrollable nested view (the RecyclerView) inside the ViewPager. Remove the AppBarLayout from the XML file of your Activity (you can take the TabLayout and ToolBar to the upper level).