Develop Reference

Android - Show fragment on resume

I currently have a navigation drawer, which has a few fragments (Home, Help, About) in my activity. On startup it opens up Home. The issue i'm having is that when i go to another fragment such as Help and then proceed to put the phone to sleep and subsequently turn on the phone back on it'll always return to Home instead of help.
I'm quite new to lifecycles but was hoping to get some feedback on how to resume from a different fragment.
EDIT: Provided relevant code
Update: Realised that this happens because i reinit the views on resume.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initializeUI();
}
private void initializeUI() {
fragAbout = new About();
fragHelp = new Help();
fragHome = new MyViewPager();
// Adding fragments to activity
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.add(R.id.main_activity_fraglayout, fragHome);
transaction.commit();
...
}
private void addDrawerItems() {
...
DrawerItemAdapter drawerAdapter = new DrawerItemAdapter(this, R.layout.nav_list_row, drawerItems);
mDrawerList.setAdapter(drawerAdapter);
mDrawerList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
switch (position) {
case 0:
...
newFragOnClick(fragHome, "Home");
break;
case 1:
...
newFragOnClick(fragSettings, "Help");
break;
case 2:
...
newFragOnClick(fragAbout, "About");
break;
default:
break;
}
}
});
}
private void newFragOnClick(Fragment frag, String actionBarTitle){
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.replace(R.id.main_activity_fraglayout, frag);
transaction.commit();
}

Use sharedpreferences to save the current tab position and in onResume() use it to move to the saved position.

Fragment disappears using SlidingTabLayout

I am using a SlidingTabLayout to implement the sliding tabs. The problem is, when backing from a fragment to the tab fragment, it disappears.
I am going to show the application flow to make things more clear.
First, I call an Activity whithin a Fragment:
public class ScreenSlidePageFragment extends Fragment{
...
public View onCreateView(args...){
...
gridView.setOnItemClickListener(new OnItemClickListener(){
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id){
switch(position){
case 0:
Intent intent = new Intent(getActivity(), FrequencyActivity.class);
startActivity(intent);
break;
}
}
}
...
}
}
The code of the FrequencyActivity is below:
public class FrequencyActivity extends AppCompatActivity{
...
protected void onCreate(Bundle savedInstance){
...
toolbar.setNavigationOnClickListener(new OnClickListener(){
#Override
public void onClick(View view){
onBackPressed();
}
});
}
final FragmentManager fm = getSupportFragmentManager();
Fragment fragment = Fragment.instantiate(getBaseContext(), "com.example.Fragment.FragmentFrequency");
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.home, fragment, "FragFrequency");
fragmentTransaction.addToBackStack("frequency");
fragmentTransaction.commit();
fm.addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
#Override
public void onBackStackChanged() {
if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
finish(); //When there is no back stack, finish the activity
} else {
//Testing purpose
int top = fm.getBackStackEntryCount();
Log.d("BACKSTACK", "Backstack count: " + String.valueOf(top));
Log.d("BACKSTACK", "Backstack name: " + fm.getBackStackEntryAt(top - 1).getName());
}
}
});
}
The FragmentFrequency is the one which contains the SlidingTabLayout, the code can be seen below:
public class FragmentFrequency extends Fragment{
...
//Creates ViewPager adapter
adapter = new ViewPagerAdapter(activity.getSupportFragmentManager(), titles, numOfTabs);
//ViewPager
viewPager = (ViewPager) layout.findViewById(R.id.pager);
viewPager.setAdapter(adapter);
//SlidingTabLayout code
...
}
And finally, the ViewPagerAdapter which loads the Fragments of the tabs
public class ViewPagerAdapter extends FragmentStatePagerAdapter{
...
#Override
public Fragment getItem(int position){
if(position == 0)
return new FragmentTab1();
else
return new FragmentTab2();
}
...
}
For example when the first tab is selected, the FragmentTab1 is loaded, which contains:
Fragment f = Fragment.instantiate(getActivity(), "com.example.Fragment.FragmentLaunchingFrequency");
FragmentTransaction tx = getActivity().getSupportFragmentManager().beginTransaction();
tx.replace(R.id.home, f, "FragLaunchingFrequency");
tx.addToBackStack("launchingfrequency");
tx.commit();
The problem is, when the back action is done, the FrequencyActivity loses the reference of the Fragment and it shows a blank. Also, the sliding tabs stop working properly.
Does anyone know how to fix this? I am really out of alternatives.
Thanks

I think you have 2 major questions in your post. Perhaps make another post for the other question.
For now, I can address your question "The problem is, when the back action is done, the FrequencyActivity loses the reference of the Fragment and it shows a blank".
Your code:
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.home, fragment, "FragFrequency");
fragmentTransaction.addToBackStack("frequency");
fragmentTransaction.commit();
fm.addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
#Override
public void onBackStackChanged() {
...
Notes:
You cannot call addToBackStack() and use OnBackStackChangedListener() in the same FragmentManager. This seems complicated.
Code suggestions:
Remove the use of addOnBackStackChangedListener() and see what happens.
Specific code suggestion:
fm.addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
#Override
public void onBackStackChanged() {
if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
finish(); //When there is no back stack, finish the activity
} else {
// Call FragmentManager.findFragmentByTag(String tag)
// Call FragmentTransaction.show() after getting the Fragment.
}
}
});
Note: Notice the else block manages the Fragment instead of depending on the BackStack (addToBackStack method).

Handling fragment back stack with Navigation Drawer

I am implementing navigation drawer and works well. So i am calling fragment on navigation drawer click and it is also working and further more i am calling another fragment from Home page fragment and maintain the back stack for every fragment but the problem is back press from the child fragment i can't go to Home page fragment and just exited from application. I don't want this. What i want Click on
Navigation Drawer->HomePageFragment->AnotherChild Fragment(On List Item click of HomePageFragment)
but on back pressed without going to Homepage fragment its directly exit with application. Here is my code: (In Fragment Activity with Navigation Drawer)
class SlideitemListener implements ListView.OnItemClickListener {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
updateDisplay(position);
}
}
private void updateDisplay(int position) {
Fragment fragment = null;
switch (position) {
case 0:
fragment = new ScheduleFragment();
break;
case 1:
fragment = new Result_Fragment();
break;
case 2:
fragment = new Live_Match_Fragment();
break;
case 3:
// fragment = new Live_Match_Fragment();
break;
case 4:
fragment = new Team_Fragment();
break;
default:
break;
}
if (fragment != null) {
fragmentManager = getFragmentManager();
fragmentManager.popBackStackImmediate("0", 0);
int count = fragmentManager.getBackStackEntryCount();
FragmentTransaction fragmentTransaction = fragmentManager
.beginTransaction();
fragmentTransaction.replace(R.id.frame_container, fragment)
.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
.addToBackStack(String.valueOf(count)).commit();
Log.e("Count in Activiy", ""+count);
// update selected item and title, then close the drawer
setTitle(menutitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
} else {
// error in creating fragment
Log.e("MainActivity", "Error in creating fragment");
}
}
Now in BackPressed() in FragmentActivity.
#Override
public void onBackPressed() {
if (fragmentManager.getBackStackEntryCount() <= 1) {
finish();
return;
}
super.onBackPressed();
}
Now calling another child fragment from HomePage fragment on Listview item click.
team_lv.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
TeamDetailFragment myDetailFragment = new TeamDetailFragment();
FragmentManager fragmentManager = getFragmentManager();
int count = fragmentManager.getBackStackEntryCount();
Log.e("Count in Fragment", "" + count);
FragmentTransaction fragmentTransaction = fragmentManager
.beginTransaction();
fragmentTransaction
.replace(R.id.frame_container, myDetailFragment)
.setTransition(
FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
.addToBackStack(String.valueOf(count)).commit();
}
});
So anybody knows then help me. Help will be appreciate.

There is an issue with nested fragments in android
https://code.google.com/p/android/issues/detail?id=40323
Android doesn't handle back press well if transactions were in nested fragments.
To surpass this i am using the following fix inside My Activity
#Override
public void onBackPressed() {
// If the fragment exists and has some back-stack entry
if (myFragment != null && myFragment.getChildFragmentManager().getBackStackEntryCount() > 0) {
// Get the fragment fragment manager - and pop the backstack
myFragment.getChildFragmentManager().popBackStack();
}
// Else, nothing in the direct fragment back stack
else {
// Let super handle the back press
super.onBackPressed();
}
}

I've solved in the following way:
1st solution
#Override
public void onBackPressed() {
FragmentManager fragmentManager = getFragmentManager();
int backCount = fragmentManager.getBackStackEntryCount();
if(backCount > 1) {
super.onBackPressed();
} else {
finish();
}
}
2nd solution
#Override
public void onBackStackChanged() {
FragmentManager fragmentManager = getFragmentManager();
int backCount = fragmentManager.getBackStackEntryCount();
if(backCount == 0) {
finish();
}
}
These allow you to exploit the Android stack when you replace your fragment:
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.content_frame, yourFragment)
.addToBackStack(null).commit();

When you press back button inside your fragment onBackPressed() method of your activity will be called if you have declared that..So handling back button for fragments within navigation drawer can be one in this way..
MainActvity
public static boolean isMainActivityShown ;
public static boolean isFragment1Shown=false ;
public static boolean isFragment2Shown=false ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
isMainActivityShown=true //inside onCreate method put isMainActivityShown true
.
.
.
{
Fragment currentFragment = new Fragment1();
isMainActivityShown=false; //when moving to fragment1
isFragment1Shown=true;
frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
.commit();
}
.
.
}
#Override
public void onBackPressed() {
if(isMainActivityShown)
{
finish();
}
else if(isFragment1Shown)
{
//write the code to handle back button when you are in Fragment1
}
else if(isFragment2Shown)
{ //When you are in Fragment 2 pressing back button will move to fragment1
Fragment currentFragment = new Fragment1();
isFragment2Shown=false;
isFragment1Shown=true;
FragmentManager frgManager;
frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
.commit();
}
}
Fragment1
Fragment currentFragment = new Fragment2();
MainActivity.isFragment1Shown=false;
MainActivity.isFragment2Shown=true;
frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
.commit();

Now you can replace finish() for fragmentManager.popBackStack(), method of android.support.v4.app.FragmentManager

How to include the activity in fragment tabs ?

I am developing an app in which there are two fragmenttabs.when pressing the tabs corresponding fragments will appear.that works fine.but what I want an activity inside the fragmenttabs. I am using ABS library for this.
ActionBar bar = getSupportActionBar();
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
ActionBar.Tab tab1 = bar.newTab();
ActionBar.Tab tab2 = bar.newTab();
tab1.setText("Fragment A");
tab2.setText("Fragment B");
tab1.setTabListener(new MyTabListener<FragmentA>(this, "tab1",
FragmentA.class, null));
tab2.setTabListener(new MyTabListener<FragmentB>(this, "tab1",
FragmentB.class, null));
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
// app icon in action bar clicked; go Location selection
Intent intent = new Intent(FragmentDemoActivity.this,
TestActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("tab", getSupportActionBar()
.getSelectedNavigationIndex());
}
listnerclass is
public class MyTabListener<T extends Fragment> implements ActionBar.TabListener {
private final FragmentActivity mActivity;
private final String mTag;
private final Class<T> mClass;
private final Bundle mArgs;
private Fragment mFragment;
public MyTabListener(FragmentActivity activity, String tag, Class<T> clz,
Bundle args) {
mActivity = activity;
mTag = tag;
mClass = clz;
mArgs = args;
FragmentTransaction ft = mActivity.getSupportFragmentManager()
.beginTransaction();
mFragment = mActivity.getSupportFragmentManager().findFragmentByTag(
mTag);
if (mFragment != null && !mFragment.isDetached()) {
ft.detach(mFragment);
}
}
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
ft = mActivity.getSupportFragmentManager().beginTransaction();
if (mFragment == null) {
mFragment = Fragment
.instantiate(mActivity, mClass.getName(), mArgs);
ft.add(android.R.id.content, mFragment, mTag);
ft.commit();
} else {
ft.attach(mFragment);
ft.commit();
}
}
#Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
ft = mActivity.getSupportFragmentManager().beginTransaction();
if (mFragment != null) {
ft.detach(mFragment);
ft.commitAllowingStateLoss();
}
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
}
Fragmentclass
public class FragmentB extends Fragment {
Button button;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup group, Bundle saved)
{
return inflater.inflate(R.layout.frag_b, group, false);
}
#Override
public void onActivityCreated (Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
button = (Button) getActivity().findViewById(R.id.button2);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle("Fragment B");
builder.setMessage("What would you like to do?");
builder.setPositiveButton("Nothing", null);
builder.setNegativeButton("Leave me alone!", null);
builder.show();
}
});
}
}
i wnt to include the following activity in the fragmentB
public class TestActivity extends Activity {
Button b1, b2;
TextView tv;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.testactivity);
b1 = (Button) findViewById(R.id.button1);
b2 = (Button) findViewById(R.id.button2);
tv = (TextView) findViewById(R.id.textView1);
b1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
tv.setText("You Clicked on Button 1");
}
});
b2.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
tv.setText("You Clicked on Button 2");
}
});
}
}
I have lot of created activites to include in the fragment..its un imaginable to recreate in onActivityCreated of fragment class. according to this I have to modify my main application.

A Fragment can't host an activity. Instead of activity, you can use Nested Fragment.
A simple tutorial: http://xperiment-andro.blogspot.com/2013/02/nested-fragments.html

You cannot run an activity inside of a fragment. At best, you can have a fragment inside of a fragment.
so the best thing you can do in this situation is instead of creating an Activity you can create a Fragment and add it inside your FragmentB.

Like Faheem Said "
A Fragment can't host an activity. Instead of activity, you can use Nested Fragment"
Fragments are just like Activities if you read the Docs.Changing your activity to Fragment is easy
This is what developer.android says
To create a fragment, you must create a subclass of Fragment (or an existing subclass of it). The Fragment class has code that looks a lot like an Activity. It contains callback methods similar to an activity, such as onCreate(), onStart(), onPause(), and onStop(). In fact, if you're converting an existing Android application to use fragments, you might simply move code from your activity's callback methods into the respective callback methods of your fragment.
Usually, you should implement at least the following lifecycle methods:
onCreate()
The system calls this when creating the fragment. Within your implementation, you should initialize essential components of the fragment that you want to retain when the fragment is paused or stopped, then resumed.
onCreateView()
The system calls this when it's time for the fragment to draw its user interface for the first time. To draw a UI for your fragment, you must return a View from this method that is the root of your fragment's layout. You can return null if the fragment does not provide a UI.
onPause()
The system calls this method as the first indication that the user is leaving the fragment (though it does not always mean the fragment is being destroyed). This is usually where you should commit any changes that should be persisted beyond the current user session (because the user might not come back).

This is the code activity inside Fragment.
YourActivityName.getSupportFragmentManager();

android: How to change views inside fragment on Click of a button

i have an action bar tab, it has two tabs, the first tabs has a fragment with a layout containing a button, wat i want to do is is when i click the button it will kinda switch the layout of the current fragment where that button belongs.. and is there any way to this stuff?.. i have an idea but it produces an nullexception on the other tab, anyway lets just concentrate on the 1st tab wherein i want to switch views when a button is clicked, here is my sample code:
MainActivity:
ActionBar acBar = getActionBar();
acBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
ActionBar.Tab tab1 = acBar.newTab().setText("Patient");
ActionBar.Tab tab2 = acBar.newTab().setText("Contact");
Fragment frag_a = new PatientFragment();
Fragment frag_b = new ContactFragment();
tab1.setTabListener(new MyTabListener(this, frag_a));
tab2.setTabListener(new MyTabListener(this, frag_b));
acBar.addTab(tab1);
acBar.addTab(tab2);
TabListener:
class MyTabListener implements ActionBar.TabListener{
private Fragment gFrag;
private Activity gAct;
public MyTabListener(Activity act, Fragment frag){
this.gFrag = frag;
this.gAct = act;
}
public void onTabReselected(Tab tab, FragmentTransaction ft) {
Toast.makeText(gAct, "Reselected!", Toast.LENGTH_LONG).show();
}
public void onTabSelected(Tab tab, FragmentTransaction ft) {
ft.replace(R.id.fragment_container, gFrag);
}
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
ft.remove(gFrag);
}
}
Fragment A:
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View view = inflater.inflate(R.layout.frag_a, container, false);
;
Button next = (Button) view.findViewById(R.id.prompt);
next.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Toast.makeText(getActivity(), "Next!",Toast.LENGTH_LONG).show();
}
});
return view;
}
Mainly i just want to switch views in the fragment, and if there is any other way that u guys know please do share tnx!

I suggest you to switch the whole Fragment. This API was designed for such purpoises.