Develop Reference

Go from activity to fragment and to another fragment

I am new at android and I can't seem to understand one thing.
I am trying to jump from MainActivity to MainFragment. In it there is a button. When onClickListener is triggered, it should jump to another ResultFragment. But I can't seem to understand how to do it.
<?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:id="#+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.something.MainActivity">
<fragment
android:id="#+id/container"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
tools:layout="#layout/fragment_main" />
</RelativeLayout>
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Fragment fragment = new MainFragment();
getSupportFragmentManager().beginTransaction().replace(R.id.container, fragment, null).commit();
}
}
public class MainFragment extends Fragment {
public MainFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
Button button = (Button) rootView.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(getContext(), "iskviesta", Toast.LENGTH_SHORT).show();
getFragmentManager().beginTransaction().replace(R.id.container, new ResultFragment()).commit();
}
});
return rootView;
}
}
public class ResultFragment extends Fragment {
public ResultFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_result, container, false);
return rootView;
}
}
What am I doing wrong? The app doesn't even start.
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.something, PID: 14245
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.something/com.something.MainActivity}: android.view.InflateException: Binary XML file line #13: Binary XML file line #13: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: android.view.InflateException: Binary XML file line #13: Binary XML file line #13: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #13: Error inflating class fragment
Caused by: java.lang.NullPointerException
at java.lang.VMClassLoader.findLoadedClass(Native Method)
at java.lang.ClassLoader.findLoadedClass(ClassLoader.java:742)
at java.lang.ClassLoader.loadClass(ClassLoader.java:362)
at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
at android.support.v4.app.Fragment.isSupportFragmentClass(Fragment.java:459)
at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:3321)
at android.support.v4.app.FragmentController.onCreateView(FragmentController.java:120)
at android.support.v4.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:378)
at android.support.v4.app.BaseFragmentActivityHoneycomb.onCreateView(BaseFragmentActivityHoneycomb.java:33)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:79)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:777)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:858)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:821)
at android.view.LayoutInflater.inflate(LayoutInflater.java:518)
at android.view.LayoutInflater.inflate(LayoutInflater.java:426)
at android.view.LayoutInflater.inflate(LayoutInflater.java:377)
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:288)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:143)
at com.something.MainActivity.onCreate(MainActivity.java:12)
at android.app.Activity.performCreate(Activity.java:6679)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

In your xml use a FrameLayout instead of Fragment:
<FrameLayout
android:id="#+id/container"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
Using a fragment tag will not allow you to do fragment transactions on the view.

You should use getSupportFragmentManager() instead of getFragmentManager in your listener :
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(getContext(), "iskviesta", Toast.LENGTH_SHORT).show();
getSupportFragmentManager().beginTransaction().replace(R.id.container, new ResultFragment()).commit();
}
});
And remplace your fragment layout with a FrameLayout in your xml code.
Hope this helps.
Sorry for my english.

Null TextView object in a fragment

I'm working on dynamically setting a text of TextView in a fragment called 'ChallengeFragment' by creating a method that sets the text. Then, I call the method in FragmentActivity class to update the TextView. However, I am getting error that TextView object is null when the method is called. I am not sure why TextView is null.
Here's the logcat message:
16:36:02.437 4072-4072/eie.android.crunch E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: eie.android.crunch, PID: 4072
java.lang.RuntimeException: Unable to start activity ComponentInfo{eie.android.crunch/eie.android.crunch.ChallengePage}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at eie.android.crunch.ChallengeFragment.setNameText(ChallengeFragment.java:76)
at eie.android.crunch.ChallengePage.onCreate(ChallengePage.java:50)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
            at android.app.ActivityThread.access$800(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5257)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Here is the Fragment class (ChallengeFragment.java):
public class ChallengeFragment extends Fragment {
private Activity mActivity;
private TextView nameText;
private Handler handler =new Handler();
public ChallengeFragment() {
}
public void onAttach(Activity activity) {
super.onAttach(activity);
mActivity = activity;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
LayoutInflater lf = getActivity().getLayoutInflater();
View v = lf.inflate(R.layout.fragment_challenge, null);
nameText = (TextView) v.findViewById(R.id.user_name_text_view);
....
return v;
}
public void setNameText(String s) {
nameText.setText(s);
}
public TextView getNameText() {
return nameText;
}
}
And this is the code for FragmentActivity that updates the text of TextView (ChallengePage.java):
public class ChallengePage extends FragmentActivity {
private FriendChallengeFragment initialFriendHabit;
private ChallengeFragment friendHabit;
private ChallengeFragment myHabit;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_challenge);
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fm.beginTransaction();
myHabit = new ChallengeFragment();
initialFriendHabit = new FriendChallengeFragment();
myHabit.onAttach(ChallengePage.this);
initialFriendHabit.onAttach(ChallengePage.this);
fragmentTransaction
.replace(R.id.my_habit, myHabit ,"fragment_top")
.replace(R.id.friend_habit, initialFriendHabit, "fragment_bottom")
.commit();
Intent intent = getIntent();
String challengedUsername = intent.getStringExtra("username");
if(challengedUsername != null) {
friendHabit = new ChallengeFragment();
friendHabit.onAttach(ChallengePage.this);
fragmentTransaction.replace(R.id.friend_habit, friendHabit, "fragment_bottom");
friendHabit.setNameText(challengedUsername);
}
}
}
And this is the layout file that contains the fragment (fragment_challenge.xml):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#color/white"
android:id="#+id/user_name_text_view"
android:layout_gravity="center_horizontal"
android:text="User Name"
android:textSize="30dp"
android:layout_marginTop="30dp"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#color/white"
android:id="#+id/habit_name_text"
android:layout_gravity="center_horizontal"
android:text="Habit Name"
android:textSize="40dp"
android:layout_marginTop="20dp"/>
<ProgressBar
android:layout_height="wrap_content"
android:layout_width="312dp"
style="#android:style/Widget.ProgressBar.Horizontal"
android:id="#+id/progressBar"
android:layout_marginTop="50dp"
android:layout_gravity="center_horizontal"/>
</LinearLayout>
I've looked at other stackoverflow questions relating to this but could not find answers.

The problem is your fragment's setNameText() method is called before onCreateView() has run, so your TextView has not been initialized yet. You have to wait until later to set the name text.
If you always have the name text when you are creating and adding the fragment, then it's better to pass that as an argument to the fragment and have it set the text of the TextView at the appropriate time. Something like this:
public class ChallengeFragment extends Fragment {
public static ChallengeFragment newInstance(String name) {
ChallengeFragment fragment = new ChallengeFragment();
Bundle args = new Bundle();
args.putString("username", name);
fragment.setArguments(args);
return fragment;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
Bundle args = getArguments();
if (args != null) {
String name = args.getString("username");
nameText.setText(name);
}
}
// everything else
}
A few things to note:
Do not create a constructor. Fragments need to have a default (no argument) constructor so that Android can instantiate them. This newInstance pattern is typically regarded as the best practice.
Use onActivityCreated because at that time you know the Activity is created and that the fragment's view hierarchy has been created.
Fragment arguments persist across configuration changes, so you shouldn't need to do anything special for that.
Also, you should not be calling onAttach() yourself, that's a lifecycle method that the OS calls on your fragment.

Unable to attach Fragment to activity through XML

I created a new activity by right clicking on my project and selecting new > fragment > blank fragment.
Here is the auto generated fragment. The only thing I added was the lines under the onCreateView() method. I also implemented onFragmentInteractionListener on the activity that I want to attatch this fragment to. I made sure to implement the onFragmentInteraction(...) method on that Activity, but left it blank.
Whats the problem here?
import android.app.Activity;
import android.net.Uri;
import android.os.Bundle;
import android.text.Html;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.support.v4.app.Fragment;
public class FragmentHowToPlay extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* #param param1 Parameter 1.
* #param param2 Parameter 2.
* #return A new instance of fragment FragmentHowToPlay.
*/
// TODO: Rename and change types and number of parameters
public static FragmentHowToPlay newInstance(String param1, String param2) {
FragmentHowToPlay fragment = new FragmentHowToPlay();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
public FragmentHowToPlay() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v = inflater.inflate(R.layout.fragment_fragment_how_to_play, container, false);
TextView text1 = (TextView) v.findViewById(R.id.text1);
text1.setText(Html.fromHtml(getString(R.string.my_text)));
return v;
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mListener = (OnFragmentInteractionListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnFragmentInteractionListener");
}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p/>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onFragmentInteraction(Uri uri);
}
}
Here is the logcat error:
Process: mjj.fling, PID: 8965
java.lang.RuntimeException: Unable to start activity ComponentInfo{mjj.fling/mjj.fling.HowToPlayActivity}: android.view.InflateException: Binary XML file line #19: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2441)
at android.app.ActivityThread.access$800(ActivityThread.java:162)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1349)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5431)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:913)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:706)
Caused by: android.view.InflateException: Binary XML file line #19: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:763)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:809)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:402)
at android.app.Activity.setContentView(Activity.java:2214)
at mjj.fling.HowToPlayActivity.onCreate(HowToPlayActivity.java:16)
at android.app.Activity.performCreate(Activity.java:6093)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
Caused by: android.app.Fragment$InstantiationException: Trying to instantiate a class mjj.fling.FragmentHowToPlay that is not a Fragment
at android.app.Fragment.instantiate(Fragment.java:606)
at android.app.Fragment.instantiate(Fragment.java:582)
at android.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2108)
at android.app.Activity.onCreateView(Activity.java:5431)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:733)
Caused by: java.lang.ClassCastException
XML LAYOUT for Activity that Fragment is being attached to
<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:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin"
tools:context="mjj.fling.HowToPlayActivity"
android:background="#01051D">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/scrollView"
android:layout_alignParentTop="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_marginTop="42dp" >
<fragment
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:name="mjj.fling.FragmentHowToPlay"
android:id="#+id/fragment"
tools:layout="#layout/fragment_fragment_how_to_play" />
</ScrollView>

You fragment extends android.support.v4.app.Fragment instead of android.app.Fragment -- see the import declaration. The former is meant to be used by FragmentActivity (or better yet the new AppCompatActivity) from the support library, not with regular android.app.Activity. You need to change one or the other and in general be consistent about what you are using throughout the app.

multiple swipeable tabs in navigation drawer

i am trying to implement multiple siwpeable tabs per section from the navigation drawer however whenever i click on my section which contains tabs it fc's displaying the following error
02-13 17:32:02.181 2275-2275/com.riara.university E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.riara.university, PID: 2275
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.riara.university/com.riara.university.SchoolsTab}: android.view.InflateException: Binary XML file line #81: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: android.view.InflateException: Binary XML file line #81: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:763)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:377)
at android.app.Activity.setContentView(Activity.java:2144)
at com.riara.university.SchoolsTab.onCreate(SchoolsTab.java:28)
at android.app.Activity.performCreate(Activity.java:5933)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.ClassCastException: Activity must implement NavigationDrawerCallbacks.
at com.riara.university.NavigationDrawerFragment.onAttach(NavigationDrawerFragment.java:212)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:903)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
at android.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1206)
at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2159)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:297)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
            at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:377)
            at android.app.Activity.setContentView(Activity.java:2144)
            at com.riara.university.SchoolsTab.onCreate(SchoolsTab.java:28)
            at android.app.Activity.performCreate(Activity.java:5933)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
java main activity
package com.riara.university;
import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.support.v4.app.FragmentActivity;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.widget.DrawerLayout;
import android.widget.Button;
public class MainActivity extends ActionBarActivity
implements NavigationDrawerFragment.NavigationDrawerCallbacks {
/**
* Fragment managing the beqhaviors, interactions and presentation of the navigation drawer.
*/
private NavigationDrawerFragment mNavigationDrawerFragment;
/**
* Used to store the last screen title. For use in {#link #restoreActionBar()}.
*/
private CharSequence mTitle;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mNavigationDrawerFragment = (NavigationDrawerFragment)
getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();
// Set up the drawer.
mNavigationDrawerFragment.setUp(
R.id.navigation_drawer,
(DrawerLayout) findViewById(R.id.drawer_layout));
}
public void onSectionAttached(int number) {
switch (number) {
case 1:
mTitle = getString(R.string.title_section1);
break;
case 2:
mTitle = getString(R.string.title_section2);
break;
case 3:
mTitle = getString(R.string.title_section3);
break;
case 4:
mTitle = getString(R.string.title_section4);
break;
case 5:
mTitle = getString(R.string.title_section5);
break;
}
}
public void restoreActionBar() {
ActionBar actionBar = getSupportActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setTitle(mTitle);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
if (!mNavigationDrawerFragment.isDrawerOpen()) {
// Only show items in the action bar relevant to this screen
// if the drawer is not showing. Otherwise, let the drawer
// decide what to show in the action bar.
getMenuInflater().inflate(R.menu.main, menu);
restoreActionBar();
return true;
}
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_website) {
Intent intent = new Intent();
intent.setAction(Intent.ACTION_VIEW);
intent.addCategory(Intent.CATEGORY_BROWSABLE);
intent.setData(Uri.parse("http://www.riarauniversity.ac.ke"));
startActivity(intent);
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public MenuInflater getMenuInflater() {
return super.getMenuInflater();
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((MainActivity) activity).onSectionAttached(
getArguments().getInt(ARG_SECTION_NUMBER));
}
}
#Override
public void onNavigationDrawerItemSelected(int position) {
FragmentManager fragmentManager = getSupportFragmentManager();
switch (position) {
case 1:
Intent intent = new Intent(this, SchoolsTab.class);
startActivity(intent);
break;
case 2:
intent = new Intent(this, PlacesDetailActivity.class);
startActivity(intent);
break;
case 3:
intent = new Intent(this, iCentreDetailActivity.class);
startActivity(intent);
break;
case 4 :
intent = new Intent(this, AboutDetailActivity.class);
startActivity(intent);
break;
}
}
}
xml activity_main
<!-- A DrawerLayout is intended to be used as the top-level content view using match_parent for both width and height to consume the full space available. -->
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:id="#+id/drawer_layout"
android:layout_width="match_parent" android:layout_height="match_parent"
tools:context="MainActivity">
<!-- As the main content view, the view below consumes the entire
space available using match_parent in both dimensions. -->
<FrameLayout android:id="#+id/container" android:layout_width="match_parent"
android:layout_height="match_parent" >
<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:background="#drawable/bg"
tools:context=".MainActivity"
android:layout_gravity="center">
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TableLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:stretchColumns="1"
>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
android:weightSum="1">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="WELCOME TO RIARA"
android:id="#+id/textView"
android:typeface="serif"
android:textColor="#472f91"
android:textSize="40px"
android:textAlignment="center"
android:clickable="false"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:gravity="center"
android:layout_gravity="center_horizontal" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="UNIVERSITY"
android:id="#+id/textView0"
android:typeface="serif"
android:textColor="#472f91"
android:textSize="38px"
android:textAlignment="center"
android:clickable="false"
android:layout_below="#+id/textView"
android:layout_centerHorizontal="true"
android:layout_gravity="center_horizontal" />
<TextView
android:layout_width="match_parent"
android:layout_height="0dp"
android:text=" University."
android:id="#+id/textView2"
android:typeface="serif"
android:textColor="#472f91"
android:scrollbarSize="20dp"
android:textStyle="bold"
android:paddingStart="0dp"
android:paddingEnd="0dp"
android:textAlignment="center"
android:layout_marginTop="69dp"
android:layout_weight="2"
android:visibility="visible"
android:gravity="center"
android:layout_marginLeft="0dp"
android:layout_marginRight="0dp"
android:layout_margin="0dp"
tools:ignore="NewApi,RtlCompat" />
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
</FrameLayout>
</LinearLayout>
</TableLayout>
</ScrollView>
</RelativeLayout>
</FrameLayout>
<fragment android:id="#+id/navigation_drawer"
android:layout_width="#dimen/navigation_drawer_width" android:layout_height="match_parent"
android:layout_gravity="start" android:name="com.riara.university.NavigationDrawerFragment"
tools:layout="#layout/fragment_navigation_drawer" />
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/ViewPager"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v4.view.ViewPager>
</android.support.v4.widget.DrawerLayout>
please help as i have been stuck at this for several hours

Fragment crashes on orientation change

Every time orientation changes Fragment crashes with error:
01-26 12:46:43.215 2895-2895/com.cbsystematic.mobile.itvdn
E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.cbsystematic.mobile.itvdn, PID: 2895
java.lang.RuntimeException: Unable to destroy activity {com.cbsystematic.mobile.itvdn/com.cbsystematic.mobile.itvdn.NavigationActivity}: java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState
at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3671)
at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3689)
at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3889)
at android.app.ActivityThread.access$900(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1284)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState
at android.support.v4.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1365)
at android.support.v4.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:516)
at com.cbsystematic.mobile.itvdn.LessonsFragment.replaceFragment(LessonsFragment.java:126)
at com.cbsystematic.mobile.itvdn.LessonsFragment.onDetach(LessonsFragment.java:119)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1080)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1108)
at android.support.v4.app.FragmentManagerImpl.dispatchDestroy(FragmentManager.java:1954)
at android.support.v4.app.FragmentActivity.onDestroy(FragmentActivity.java:313)
at android.support.v7.app.ActionBarActivity.onDestroy(ActionBarActivity.java:169)
at android.app.Activity.performDestroy(Activity.java:6112)
at android.app.Instrumentation.callActivityOnDestroy(Instrumentation.java:1140)
at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3658)
            at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3689)
            at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3889)
            at android.app.ActivityThread.access$900(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1284)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
I need to save state of current Fragment.
Fragment class code:
public class LessonsFragment extends Fragment implements AbsListView.OnItemClickListener {
private OnFragmentInteractionListener mListener;
/**
* The fragment's ListView.
*/
private AbsListView mListView;
/**
* The Adapter which will be used to populate the ListView/GridView with
* Views.
*/
private ListAdapter mAdapter;
private static String courseUrl;
private ParserJson parserJson = new ParserJson();
private TextView descriptionTextView;
private DescriptionData descriptionData;
// TODO: Rename and change types of parameters
public static LessonsFragment newInstance(String url) {
LessonsFragment fragment = new LessonsFragment();
courseUrl = url;
return fragment;
}
/**
* Mandatory empty constructor for the fragment manager to instantiate the
* fragment (e.g. upon screen orientation changes).
*/
public LessonsFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// TODO: Change Adapter to display your content
mAdapter = new LessonsItemAdapter(getActivity(),
R.layout.lessons_list_item, parserJson.getLessons(courseUrl).getLessonsArray());
descriptionData = parserJson.getLessons(courseUrl).getDescriptionData();
}
// #Override
// public void onSaveInstanceState(Bundle outState) {
// //No call for super(). Bug on API Level > 11.
// }
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_lessons_list, container, false);
descriptionTextView = (TextView) view.findViewById(R.id.lessons_description);
descriptionTextView.setText("Описание курса:\n" +
descriptionData.getShortDescription());
// Set the adapter
mListView = (AbsListView) view.findViewById(android.R.id.list);
((AdapterView<ListAdapter>) mListView).setAdapter(mAdapter);
// Set OnItemClickListener so we can be notified on item clicks
mListView.setOnItemClickListener(this);
return view;
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mListener = (OnFragmentInteractionListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnFragmentInteractionListener");
}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
//this occurs when we move out of this Fragment
replaceFragment(CatalogFragment.newInstance(1));
}
private void replaceFragment (Fragment fragment){
String backStateName = fragment.getClass().getName();
String fragmentTag = backStateName;
boolean fragmentPopped = getFragmentManager().popBackStackImmediate (backStateName, 0);
if (!fragmentPopped && getFragmentManager().findFragmentByTag(fragmentTag) == null){ //fragment not in back stack, create it.
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.container, fragment, fragmentTag);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
ft.addToBackStack(backStateName);
ft.commit();
}
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
if (null != mListener) {
mListener.onLessonFragmentInteraction(parserJson.getLessons(courseUrl).getLessonsArray().get(position).getId());
}
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p/>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onLessonFragmentInteraction(String id);
}
}
Manifest:
<?xml version="1.0" encoding="utf-8"?>
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".AuthorizationActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".NavigationActivity"
android:parentActivityName="com.cbsystematic.mobile.itvdn.AuthorizationActivity" >
<!-- The meta-data element is needed for versions lower than 4.1 -->
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.cbsystematic.mobile.itvdn.AuthorizationActivity" />
>
</activity>
</application>
Fragment's layout:
<?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:id="#+id/fragment_lessons"
android:background="#FAF9F9"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.cbsystematic.mobile.itvdn.LessonsFragment">
<TextView
android:id="#+id/lessons_description"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textColor="#acacac" />
<ListView android:id="#android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#id/lessons_description"/>
I know that such problems are like pain in the neck. But please give your assumptions.
Will appreciate any help.

It crashes because the fragment gets recreated everytime you change the orientation.
Add this line to your activity in the manifest:
android:configChanges="keyboardHidden|orientation|screenSize"