Develop Reference

How to transfer data from one activity to a fragment with Firebase?

Hey I was wondering how I could transfer data from one activity to a fragment using fire base. I have edit text in the activity class and a list view in the Fragment.
I would like to display the information throughout the app database so that other users can see and edit the information too.

I dont know if the IDE matters but passing information to a fragment is usually done with fragment arguments. You need to create a static "newInstance" method in your fragment that you can call from the activity and pass whatever info to the fragment through it. Something like this:
public static mListFragment newInstance(String fromActivity) {
mListFragment fragment = new mListFragment ();
Bundle args = new Bundle();
args.putString("STIRNG_FROM_ACTIVITY", fromActivity);
fragment.setArguments(args);
return fragment;
}
You can then call the method from the activity like this:
FragmentManager fm = getFragmentManager().beginTransaction();
mListFragment fragment = new mListFragment();
fragment = mListFragment.newInstance("info_to_send");
fragmentTransaction.add(R.id.fragments_frame, fragment);
From here you can even persist the info across device screen orientation changes..

Just use firebaseRef to setValue() and set the value from the edittext.
Add ValueListener on the fragment to get the same value from dataSnapshot.
:D
https://github.com/firebase/quickstart-java/tree/master/database/src/main/java/com/google/firebase/quickstart

Detecting when a fragment is on top again (has focus)

In my app, my activity has a container with a fragment. When a button in that fragment is clicked, I add a new fragment to the container and add the previous fragment to the backstack.
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.add(R.id.primary_fragment_container, homeFragmentHandler);
fragmentTransaction.addToBackStack(folderId.toString());
fragmentTransaction.commit();
The result is that pressing back closes the top fragment and returns me to the previous fragment, which is exactly how I want it. HOWEVER there are certain elements on the fragment that should be refreshed at this point. When the user clicks back and is returned to the previous fragment, how do I know to refresh the data within that fragment? is there a method such as onResume() for this scenario?

You have to proper add fragments to backstack:
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
MyFragment fragment = new MyFragment ();
transaction.replace(R.id.primary_fragment_container, fragment).addToBackStack(null).commit();

Fragment homeFragmentHandler= new Fragment();
Bundle bundle = new Bundle();
//replace this line below wth something convinient
bundle.putInt("key", value);
fragment.setArguments(bundle);
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.add(R.id.primary_fragment_container, homeFragmentHandler);
fragmentTransaction.addToBackStack(folderId.toString());
fragmentTransaction.commit();
This will send data regarding which fragment/ activity caused the previous fragment to load. Now in its onCreate add this code to check the data in the bundle
//In the onCreate of the original fragment
Bundle bundle = this.getArguments();
if(bundle.getInt(key, defaultValue)!=null{
int myInt = bundle.getInt(key, defaultValue);
// Load the data that needs to be refreshed when original fragment is loaded from the second one
}
No else statement is needed. If the fragment is made from any other activity/ fragment then the bundle.getInt will return null and hence that code inside the statement wont be executed.

How to update the content of a TextView in a fragment in navagation drawer in Android

I'am new to Android application developpement. I'am trying to create an application using navigation drawer. I created an apllication with the navigation drawer template with android studio. Then i changed it to redirect the user to a new fragment_layout each time he chooses a new item in the navigation menu. Now, my first fragment contains a listview, and onclick on one item of the list i am redirected to a detailfragment which contains a TextView.
When i tried to populate this TextView with details of the selected item i had a null pointer exception.After two days of research and trying to find out what is the problem i discovered that my visible fragment returns false when i call fragment.isInLayout().
Thanks for your help.
My code :
Creation of a new fragment :
VideoDetailFragment fragment = new VideoDetailFragment();
Bundle bundle = new Bundle();
bundle.putString("title", title)
fragment.setArguments(bundle);
FragmentTransaction transaction = getFragmentManager().beginTransaction();
transaction.replace(R.id.container, fragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();
getFragmentManager().executePendingTransactions();
if (fragment.isInLayout()) {
fragment.replaceText("Lalala");}
And the method replaceText code is :
public void replaceText(String text){
textView.setText(text);
}
The problem is that the methode replaceText is not reached And when i remove the if statement a null pointer exception is raised saying that i can not write in the textView
EDIT: I think the problem is with transaction.replace(R.id.container,fragment);, maybe there is another alternative to replace a fragment_layout content. Because, i have the VideoDetailFragment displayed in the simulator and i can't change it's content, Also when i tired VideoDetailFragment fragment1 = (VideoDetailFragment)getFragmentManager().findFragmentById(R.id.container);
it gave me a cast exception.
Thanks a lot for your help, really need it :)

Try to do something like this:
Fragment fragment = new Fragment();
Bundle bundle = new Bundle();
bundle.putString(key, value);
fragment.setArguments(bundle);
Then in your second Fragment, retrieve the data (you could do it for example in onCreate()) with:
Bundle bundle = this.getArguments();
int myString = bundle.getString(key, ""); //the second parameter is a default value
Or show your code to see where do you get NullPointerException

YourFragment fragment = getSupportFragmentManager().findFragmentById(R.id.your_fragment);
if (fragment != null) {
fragment.yourUpdateDataMethod(youData);
}

How to get Data from current fragment to other fragment?

I am using Fragment for my current application. Here I have one Fragment FA and I am navigating to the other Fragment FB and I have added FA to the backstack as I want to come to FA fragment on some event to be done in FB fragment. I have a done button in the fragment FB. On Click of that button I need to do two things in the fragment FB which are as follows :-
(a). I need to finish the current fragment FB.
(b). Secondly, I need to pass some data from FB to already existing Fragment FA as I have added it to backstack.
I have just started using Fragments and don't know much about them and I want to sort out this problem.Can anyone suggest something for this, any Help would be appreciable.
Thanks in Advance.

You can pass data from one fragment to another something like below.
Fragment fragment;
fragment = new SingleImage();
Bundle bundle = new Bundle();
bundle.putString("img",actorsList.get(position).getImage());
bundle.putString("desc",actorsList.get(position).getDesc());
fragment.setArguments(bundle);
getActivity().getFragmentManager().beginTransaction().replace(R.id.content_frame, fragment).addToBackStack( "tag" ).commit();
means you can add arguments with fragment to pass to another.
and you can get that data in another fragment using below code
Bundle bundle = this.getArguments();
if(bundle != null)
{
tvdesc.setText(bundle.getString("desc"));
img_url= bundle.getString("img");
}
Since you want only one back stack entry per Fragment, make the back state name the Fragment's class name (via getClass().getName()). Then when replacing a Fragment, use the popBackStackImmediate() method. If it returns true, it means there is an instance of the Fragment in the back stack. If not, actually execute the Fragment replacement logic.
private void replaceFragment (Fragment fragment){
String backStateName = fragment.getClass().getName();
FragmentManager manager = getSupportFragmentManager();
boolean fragmentPopped = manager.popBackStackImmediate (backStateName, 0);
if (!fragmentPopped){ //fragment not in back stack, create it.
FragmentTransaction ft = manager.beginTransaction();
ft.replace(R.id.content_frame, fragment);
ft.addToBackStack(backStateName);
ft.commit();
}
}

How to send data from one Fragment to another Fragment?

Hi I know there are answers of this question. I have tried all of them but it is not working in my app.
I am developing an app that has 3 Fragment activity. First fragment shows a website, second fragment has listview and third Fragment has another listview. Now I want to send URL from third fragment to first fragment when user clicks on listitem..This is what I have done.
I am sending string url from this Fragment to first fragment.
list.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapter, View view, int position,
long id) {
FragmentC fragment = new FragmentC();
final Bundle bundle = new Bundle();
bundle.putString("position", "http://www.facebook.com"); fragment.setArguments(bundle);}
});
This is first fragment where I need the url and Want to show in the webview.
String url="http://www.hotelsearcher.net/";
Bundle args = getArguments();
if (args != null){
url = args.getString("position");
}
WebView webView= (WebView) V.findViewById(R.id.webView1);
WebSettings webViewSettings = webView.getSettings();
webViewSettings.setJavaScriptCanOpenWindowsAutomatically(true);
webViewSettings.setJavaScriptEnabled(true);
webViewSettings.setPluginState(PluginState.ON);
webView.loadUrl(url);
When I click on list item I don't see anything . It does not redirect me to the first fragment.Please help me..

Use Bundle to send String:
//Put the value
YourNewFragment ldf = new YourNewFragment ();
Bundle args = new Bundle();
args.putString("YourKey", "YourValue");
ldf.setArguments(args);
//Inflate the fragment
getFragmentManager().beginTransaction().add(R.id.container, ldf).commit();
In onCreateView of the new Fragment:
//Retrieve the value
String value = getArguments().getString("YourKey");

1.If fragments are hosted by same activity- You cannot cast an intent to Fragment. Fragment acts as a part of Activity, it is not an activity by itself. So to share a string between fragments you can declare a static String in Activity. Access that string from Fragment A to set the value and Get the string value in fragment B.
2.Both fragments are hosted by different Activities- Then you can use putExtra to pass a string from Fragment A of Activity A to Activity B. Store that string in Activity B and use it in Fragment B.

You have to attach your bundle to your fragment.
fragment.setArguments(bundle);
and after that change or replace the new fragment.
You have to be sure that the String is in the new Fragment. Debugging!!

You can send data by two ways
First when you want to start that fragment while sending data
SecondFragment ldf = new SecondFragment ();
Bundle args = new Bundle();
args.putString("YourKey", "YourValue");
ldf.setArguments(args);
//Inflate the fragment
getFragmentManager().beginTransaction().add(R.id.container, ldf).commit();
Second, when you want to send data without open your fragment
FragmentTransaction ft = mFragmentManager.beginTransaction();
ft.add(R.id.fragContainer1, new ModelListFragment(), FRAG_MODEL_LIST);
ft.add(R.id.fragContainer2, new TrimListFragment(), FRAG_TRIM_LIST);
ft.commit();
Fragment fragment = mFragmentManager.findFragmentByTag(MainActivity.FRAG_MODEL_LIST);
Log.d("MY", "found fragment: " + (fragment != null));