Develop Reference

How to Load Fragment if it is not Null - Android?

I need some help as I am a bit new in android, in my android app that I am working on, I am navigating between Fragments all the time. I use the code to navigate between Fragments.
private void displaySelectedScreen(int id){
Fragment fragment=null;
String fragment_tag="";
switch(id)
{
case R.id.nav_listen:
fragment=new ListenFragment();
fragment_tag="LISTENTAG";
break;
case R.id.nav_programs:
break;
case R.id.nav_stories:
break;
case R.id.nav_about:
break;
case R.id.nav_feedback:
break;
case R.id.nav_share:
shareTextUrl();
break;
}
if(fragment!=null){
FragmentTransaction ft=getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame,fragment,fragment_tag);
ft.commit();
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
}
I just need to check that if the fragment exists(loaded) before, containter should show the previously loaded fragment. However, if the Fragment was not loaded before the Fragment should be loaded for the first time.
Could anyone help me about making this happen?
Thank you very much.
Code inside my fragment:(ListenFragment.java)
public class ListenFragment extends Fragment
{
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState)
{
super.onViewCreated(view, savedInstanceState);
getActivity().setTitle("Listen Live");
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
final View InputFragmentView=inflater.inflate(R.layout.listen_layout,container,false);
return InputFragmentView;
}

You don't need to declare the variables reference to Fragment's instance. Instead, save your fragment by tag then get it. Like that:
Fragment fragment = getSupportFragmentManager().findFragmentByTag("fragment_tag");
if(fragment == null) {
fragment=new ListenFragment();
}
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame, fragment, fragment_tag);
ft.commit();

use below methods to get the Fragment:
getFragmentManager().findFragmentById(R.is.xyz)
getFragmentManager().findFragmentByTAG("XYZ")
then use to start Fragment :
supportFragmentManager.beginTransaction()
there is a similar question here it might help:
Check if a fragment exists and reuse it

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.

Navigation Drawer Fragments

So I have my navigation drawer with 5 different options. They all open a new fragment that I have created. The first one is Home, and I am trying to find a way to bring it back to the first screen that shows up under the navigation drawer. It has the id of "container", in the main_activity.xml. I do not want to use and intent to call the entire class again to load up. Also I do not want to be able to use the back button from another intent. I am confused on how to make this happen.
#Override
public void onNavigationDrawerItemSelected(int position) {
FragmentHowItWorks fragmentHow;
FragmentSettings fragmentSettings;
FragmentTransaction transaction = getFragmentManager().beginTransaction();
switch(position){
case 0:
// should I call the layout?
// this is the "Home" option
break;
case 1:
fragmentHow = new FragmentHowItWorks();
transaction.replace(R.id.container, fragmentHow);
transaction.addToBackStack(null);
transaction.commit();
break;
case 2:
fragmentSettings = new FragmentSettings();
transaction.replace(R.id.container, fragmentSettings);
transaction.addToBackStack(null);
transaction.commit();
break
case 3:
fragment = new FragmentHowItWorks();
transaction.replace(R.id.container, fragment);
transaction.addToBackStack(null);
transaction.commit();
break;
case 4:
fragment = new FragmentHowItWorks();
transaction.replace(R.id.container, fragment);
transaction.addToBackStack(null);
transaction.commit();
break;
}
}

Use methods add,hide and show,
Step1 Prepare all your fragments
Fragment fragment1 = new FragmentOne();
Fragment fragment2 = new FragmentTwo();
Fragment fragment3 = new FragmentThree();
Fragment mCurrentFragment = null;
Step2 Show/hide your fragments
#Override
public void onNavigationDrawerItemSelected(int position) {
Fragment fragment;
switch (position) {
case 1:
fragment = fragment1;
break;
case 2:
fragment = fragment2;
break;
case 3:
fragment = fragment3;
break;
}
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
if(mCurrentFragment == null) {
ft.add(R.id.container, fragment).commit();
mCurrentFragment = fragment;
} else if(fragment.isAdded()) {
ft.hide(mCurrentFragment).show(fragment).commit();
} else {
ft.hide(mCurrentFragment).add(R.id.container, fragment).commit();
}
mCurrentFragment = fragment;
}

You can do this ,
You can get the name of current fragment which is in the container . This will return name including the package + fragment name
String name = getFragmentManager().findFragmentById(container id ).getClass().getName();
When you click on the home index of drawer, check weather the current name id equal to the home.
If it is home, you don't need to perform any action.

I know that this was asked and answered long time ago but, I would like to show my approach on this problem, maybe it will help anyone else:
I added a Fragment Name over each Fragment that I use like:
public class MainFragment extends BaseFragment {
public static final String FRAGMENT_TAG = "main";
// ... all your fragment
}
And on the Drawer Layout:
public void methodThatSetsTheUi() {
mDrawerView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
getFragmentManager().findFragmentByTag("main");
String tag = getFragmentTag(position);
replaceFragment(getOrCreateFragment(tag), tag);
mDrawerLayout.closeDrawer(mDrawerView);
}
});
}
#NonNull
private String getFragmentTag(int position) {
String tag;
switch (position) {
case MAIN_FRAGMENT_DRAWER_POSITION:
tag = MainFragment.FRAGMENT_TAG;
break;
case FAVORITE_FRAGMENT_DRAWER_POSITION:
tag = FavoriteFragment.FRAGMENT_TAG;
break;
default:
throw new AssertionError("That selection is wrong");
}
return tag;
}
private BaseFragment getOrCreateFragment(String fragmentName) {
BaseFragment fragment = (BaseFragment) getFragmentManager().findFragmentByTag(fragmentName);
if(fragment == null) {
fragment = FragmentFactory.createFragment(fragmentName);
}
return fragment;
}
and well, the FragmentFactory is just a simple Factory:
public final class FragmentFactory {
public static BaseFragment createFragment(String fragmentName) {
switch(fragmentName) {
case MainFragment.FRAGMENT_TAG:
return MainFragment.newInstance();
case FavoriteFragment.FRAGMENT_TAG:
return FavoriteFragment.newInstance();
// ... all fragments here.
default:
return null;
}
}
Hope to help someone.

Backstack android fragment navigation

This is how I used navigation drawer to display Fragments:
private void displayView(int position) {
// update the main content by replacing fragments
Fragment fragment = null;
switch (position) {
case 0:
fragment = new Fragment0();
break;
case 1:
fragment = new Fragment1();
break;
case 2:
fragment = new Fragment2();
break;
case 3:
fragment = new Fragment3();
break;
case 4:
fragment = new Fragment4();
break;
case 5:
fragment = new Fragment5();
}
default:
break;
}
if (fragment != null) {
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.frame_container, fragment)
.addToBackStack(null)
.commit();
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
mDrawerList.setSelection(position);
setTitle(navMenuTitles[position]);
mDrawerLayout.closeDrawer(drawerll);
} else {
// error in creating fragment
Log.e("MainActivity", "Error in creating fragment");
}
}
Suppose if the user navigates to Fragment 2-> Fragment 5-> Fragment3.
If the user clicks the back button I need to have the descending order and on each fragment I am displaying the name of the Fragment when he goes to that particular fragment ie:
Fragment 3-> Fragment 5-> Fragment2.
This is what I have tried:
First Method:
FragmentManager fm = getSupportFragmentManager();
int count = fm.getBackStackEntryCount();
for(int i = 0; i < count; ++i) {
fm.popBackStackImmediate();
}
Second Method:
fragmentManager.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
I'm unable to get this working**(ie.. I'm unable to move it back to the fragment where I have come from**) and unable to display the name of the fragment based on the backstack
Any help is greatly appreciated.

Your navigation is working fine I guess and the issue you are facing is the tittle for which you can use
public class SampleFragment extends Fragment{
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Creating view correspoding to the fragment
View v = inflater.inflate(R.layout.fragment_layout, container, false);
// Updating the action bar title
getActivity().getActionBar().setTitle("Screen name");
return v;
}
}
in every fragment. And whenever you backpress the onCreateView method of fragmemt(the one which is poping from the backstack) gets called and the tittle will again set replacing the old tittle.

1. Handle back
You can use getSupportFragmentManager().popBackStack() method in onBackPressed:
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack();
getSupportFragmentManager().beginTransaction().commit();
}
else {
super.onBackPressed();
}
}
Don't forget to add the fragment in BackStack like :
transaction.addToBackStack(null);
2. Display Name
To show the current fragment name in actionbar, you can get it on onResume of your Fragment :
#Override
protected void onResume() {
super.onResume();
((FrgmentActivtiyName)getActivity).changeTitle("title");
}
Define a method which set the title in the actionbar in your FrgmentActivity:
public void changeTitle(String titleToSet) {
// set title as titleToSet
}
Hope it helps ツ

Please try this:
In the activity which holds the fragments, override the onbackPressed() method by,
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack();
getSupportFragmentManager().beginTransaction().commit();
}
else {
super.onBackPressed();
}
}

if (fragment != null) {
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.frame_container, fragment).commit();
menuList.setItemChecked(position, true);
menuList.setSelection(position);
}

Add different fragment to an activity based on Intent-given identifier

I'm working on an application where in layout layout-small-portrait I want to launch different fragments contained in a single "container activity", named SingleActivity. I will handle this differnetly in layouts layout-land, layout-large etc. but that is unrelated to my problem.
I have an activity MainActivity which is, as the name indicates, the main activity (launcher) of my application. This will initially contain a ListFragment with different items for the user to press.
Based on the item that the user presses the SingleActivity will launch and its content will correspond to a specific Fragment related to this item. My problem starts here. When the user presses an item I have a reference to the corresponding fragment I want to be displayed in SingleFragment. Illustrated below:
String tag = myFragmentReference.getTag();
Intent i = new Intent(this, SingleActivity.class);
i.putExtra(SingleActivity.CONST_TAG, tag);
startActivity(i);
The activity launches successfully. In SingleActivity I have the following onCreate() method:
...
// Retrieve the fragment tag from the intent
String tag = getIntent().getStringExtra(CONST_TAG);
Fragment fragment = getSupportFragmentManager().findFragmentByTag(tag);
if(fragment == null) {
// always end up here, this is my problem.
}
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.add(R.id.fragmentContainer, fragment);
ft.commit();
...
I suspect that the fact that fragment is always null is because the fragment has not been inflated yet. If I am right what I need to do is define a fragment's tag before it is inflated, so that it can be found by findFragmentByTag(). Is that possible?
If anything is unclear please let me know.
I look forward to hearing some good ideas! If there are better or more clever ways to implement this I would love to hear your thoughts! Thanks :)

Since you are jumping to another activity, it will have its own Fragment BackStack and that fragment will not exist.
You will have to inflate the fragment in the new activity something along these lines:
String tag = intent.getStringExtra(CONST_TAG);
if (getSupportFragmentManager().findFragmentByTag(tag) == null) {
Fragment fragment = Fragment.instantiate(this, tag, extras);
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.add(R.id.fragmentContainer, fragment, tag);
ft.commit();
}
The tag string will need to have the package location of the fragment such as "com.android.myprojectname.myfragment"

First use SlidingMenu library: https://github.com/jfeinstein10/SlidingMenu
This will help you, and your app will be more cool, that´s the only way that I can help you make what you need so, here is the code:
Here is your MainActivity:
I´ll try to explain this sample code and you use for your need.
This is the ListFragment of your BehindContent (SlidingMenu):
public class ColorMenuFragment extends ListFragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.list, null);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
String[] colors = getResources().getStringArray(R.array.color_names);
ArrayAdapter<String> colorAdapter = new ArrayAdapter<String>(getActivity(),
android.R.layout.simple_list_item_1, android.R.id.text1, colors);
setListAdapter(colorAdapter);
//This array is only to fill SlidingMenu with a Simple String Color.
//I used MergeAdapter from Commonsware to create a very nice SlidingMenu.
}
#Override
public void onListItemClick(ListView lv, View v, int position, long id) {
//This switch case is a listener to select wish item user have been selected, so it Call
//ColorFragment, you can change to Task1Fragment, Task2Fragment, Task3Fragment.
Fragment newContent = null;
switch (position) {
case 0:
newContent = new ColorFragment(R.color.red);
break;
case 1:
newContent = new ColorFragment(R.color.green);
break;
case 2:
newContent = new ColorFragment(R.color.blue);
break;
case 3:
newContent = new ColorFragment(android.R.color.white);
break;
case 4:
newContent = new ColorFragment(android.R.color.black);
break;
}
if (newContent != null)
switchFragment(newContent);
}
// the meat of switching the above fragment
private void switchFragment(Fragment fragment) {
if (getActivity() == null)
return;
if (getActivity() instanceof FragmentChangeActivity) {
FragmentChangeActivity fca = (FragmentChangeActivity) getActivity();
fca.switchContent(fragment);
} else if (getActivity() instanceof ResponsiveUIActivity) {
ResponsiveUIActivity ra = (ResponsiveUIActivity) getActivity();
ra.switchContent(fragment);
}
}
}
Here is your BaseActivity Class:
It dont have swipe, as I could understand, you don't need this.
public class FragmentChangeActivity extends BaseActivity {
private Fragment mContent;
public FragmentChangeActivity() {
super(R.string.changing_fragments);
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// set the Above View
if (savedInstanceState != null)
mContent = getSupportFragmentManager().getFragment(savedInstanceState, "mContent");
if (mContent == null)
mContent = new ColorFragment(R.color.red);
// set the Above View
//This will be the first AboveView
setContentView(R.layout.content_frame);
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.content_frame, mContent)
.commit();
// set the Behind View
//This is the SlidingMenu
setBehindContentView(R.layout.menu_frame);
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.menu_frame, new ColorMenuFragment())
.commit();
// customize the SlidingMenu
//This is opcional
getSlidingMenu().setTouchModeAbove(SlidingMenu.TOUCHMODE_FULLSCREEN);
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
getSupportFragmentManager().putFragment(outState, "mContent", mContent);
}
public void switchContent(Fragment fragment) {
// the meat of switching fragment
mContent = fragment;
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.content_frame, fragment)
.commit();
getSlidingMenu().showContent();
}
}
Ok, So If you want to change the ColorFragment to anything else, do this:
First, choice the item that you want to use:
case 0:
newContent = new ColorFragment(R.color.red);
break;
to:
case 0:
newContent = new ArrayListFragment();
break;
I have made just a arraylist, it is just a simple example, you can do a lot of thing, then you can read about Fragment to learn how to do different things.
public class ArrayListFragment extends ListFragment {
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
setListAdapter(new ArrayAdapter<String>(getActivity(),
android.R.layout.simple_list_item_1, Listnames.TITLES));
//Listnames is a class with String[] TITLES;
}
#Override
public void onListItemClick(ListView l, View v, int position, long id) {
Log.i("FragmentList2", "Item clicked: " + id);
String item = (String) getListAdapter().getItem(position);
Toast.makeText(getActivity(), item, Toast.LENGTH_LONG).show();
}
}
As you see, it can display a different fragment based on which item in the ListFragment (MainActivity) the user presses.
Well, if you misunderstood something, just tell me.