Develop Reference

Communication between two fragments - which is right way?

I have read this manual and also i'm reading this book. developer.android.com says i should implement communication through activity. But the book says i can use setTargetFragment() and call onActivityResult() by hand for target fragment from other fragment. Each approach works but which is right? What is setTargetFrament() for, if i can't use it for communication with other fragment?

setTargetFrament() and getTargetFrament() can be used in the context of one fragment that starts another fragment. The first fragment can pass its self as a reference to the second fragment:
MyFragment newFrag = new MyFragment();
newFrag.setTargetFragment(this, 0);
getFragmentManager().beginTransaction().replace(R.id.frag_one, newFrag).commit();
Now newFrag can use getTargetFrament() to retrieve the oldFrag and access methods from oldFrag directly.
This is not however something that is recommanded to be used on an usual basis.
The recommanded way of communication between fragments is to be done through the parent activity, as the docs mention:
Often you will want one Fragment to communicate with another,
for example to change the content based on a user event.
All Fragment-to-Fragment communication is done through the associated Activity.
Two Fragments should never communicate directly.
Here is a example of that:
the layout for the main activity:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<FrameLayout
android:id="#+id/frag_one"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"/>
<FrameLayout
android:id="#+id/frag_two"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"/>
</LinearLayout>
the Activity:
public class MainActivity extends Activity
{
private MyFragment f1;
private MyFragment f2;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Bundle b1 = new Bundle();
b1.putString("name", "Fragment One");
f1 = MyFragment.createNew(b1);//we create a new fragment instance
f1.setOnReceiveListener(new MyFragment.ReceiveListener()//we create a new ReceiveListener and pass it to the fragment
{
#Override
public void recv(String str)
{
//f1 has sent data to the activity, the activity passes forward to f2
f2.send(str);
}
});
//we attach the fragment to the activity
getFragmentManager().beginTransaction().add(R.id.frag_one, f1, "frag_one").commit();
//we repeat the above process for the second fragment
Bundle b2 = new Bundle();
b2.putString("name", "Fragment Two");
f2 = MyFragment.createNew(b2);
f2.setOnReceiveListener(new MyFragment.ReceiveListener()
{
#Override
public void recv(String str)
{
f1.send(str);
}
});
getFragmentManager().beginTransaction().add(R.id.frag_two, f2, "frag_two").commit();
}
}
The fragment layout:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<Button
android:id="#+id/frag_btn"
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:layout_alignParentTop="true"/>
<TextView
android:id="#+id/frag_txt"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_below="#+id/frag_btn"
android:textSize="10sp"/>
</RelativeLayout>
The fragment class:
public class MyFragment extends Fragment
{
private ReceiveListener recv_list;
private Button btn;
private TextView txt;
//static factory function that creates new fragments
public static MyFragment createNew(Bundle b)
{
MyFragment f = new MyFragment();
f.setArguments(b);
return f;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
return inflater.inflate(R.layout.fragment, container, false);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState)
{
super.onViewCreated(view, savedInstanceState);
btn = (Button) view.findViewById(R.id.frag_btn);
txt = (TextView) view.findViewById(R.id.frag_txt);
//we retrieve the passed arguments (in this case the name)
Bundle b = getArguments();
final String name = b.getString("name");
btn.setText(name);
btn.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
if(null != recv_list)
{
//now we pass the data to the parent activity
recv_list.recv(name + " says hello!");
}
}
});
}
//the activity passes data to the fragment using this method
public void send(String s)
{
txt.append(s + "\n");
}
//helper method that will set the listener
public void setOnReceiveListener(ReceiveListener l)
{
recv_list = l;
}
//the declaration of the listener
public interface ReceiveListener
{
public void recv(String str);
}
}

Get edittext value from fragment

I am using fragments,I have an edittext in fragment and I want to get value in main activity.
This is my fragment layout
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#878787" >
<TextView android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="dfgdfgdf"
android:textSize="20dp"
android:layout_centerInParent="true"
android:id="#+id/user_name"/>
<EditText
android:id="#+id/message"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<Button
android:text="Gönder"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:onClick="getFromUser"
android:layout_marginTop="40dp"
/>
</RelativeLayout>
I am loading fragment with this function:
public void startChat(JsonObject user) {
FrameLayout layout = (FrameLayout)findViewById(R.id.container);
layout.setVisibility(View.VISIBLE);
Bundle bundle = new Bundle();
bundle.putString("name", user.get("name").getAsString());
sendTo=user.get("username").getAsString();
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
ConversationFragment conv = new ConversationFragment();
conv.setArguments(bundle);
fragmentTransaction.add(R.id.container, conv);
fragmentTransaction.commit();
viewPager.setVisibility(View.GONE);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setDisplayHomeAsUpEnabled(true);
}
And this is my fragment class
public class ConversationFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
String name = getArguments().getString("name");
View rootView = inflater.inflate(R.layout.fragment_conversation, container, false);
TextView username=(TextView)rootView.findViewById(R.id.user_name);
username.setText(name);
return rootView;
}
}
As you can see when press the button main activity runs "getFromUser" function.I want to get edittext value in this function.How can I do this ?

It's always the same procedure for these things. You can't access a fragment's views just like that. You need a callback method.
Add this code to ConversationFragment:
private OnGetFromUserClickListener mListener;
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mListener = (OnGetFromUserClickListener ) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString() + " must implement OnGetFromUserClickListener");
}
}
public void getFromUser(View v) {
if (mListener != null) {
EditText edit = (EditText)findViewById(R.id.message);
mListener.getFromUser(edit.getText().toString());
}
}
public interface OnGetFromUserClickListener {
void getFromUser(String message);
}
Make your MainActivity implement this interface. Replace getFromUser() inside MainActivity with:
public void getFromUser(String message) {
sendMessage(message);
}
Done.
Edit:
Actually, using the XML-onClick attribute is currently bugged (see onClick inside fragment called on Activity): It links to the activity instead of the fragment. You have to set the click listener programmatically to make sure the code won't break at some point in the future. So give the button an ID inside the XML (e.g. get_from_user) and add this code to onCreateView inside ConversationFragment:
v.findViewById(R.id.get_from_user).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (v.getId() == R.id.get_from_user) {
getFromUser(v);
}
}
});
Using this code vastly decouples the activity and the fragment from each other.

I resolved this problem.
public void getFromUser(View view) {
ConversationFragment fragment1 = (ConversationFragment)getSupportFragmentManager().findFragmentById(R.id.container);
View frag=fragment1.getView();
EditText editText1 =(EditText) frag.findViewById(R.id.message);
String message=editText1.getText().toString();
sendMessage(message);
}
Now I can get edittext value from fragment.

Accessing Views inside fragment

I'm having troubles accessing the Views that within my Fragment. In the example below, I can't access the 2nd button that is within the Fragment (e.g., findViewById appears to return NULL and the app crashes when I try b2.setText("test") ), but when I directly add it in the activity_main.xml, it does work.
Here is the code:
MainActivity.java
public class MainActivity extends Activity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button fragmentButton = (Button)findViewById(R.id.iMainButton);
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.add(R.id.iMainInnerLLContainer, new TestFragment());
ft.commit();
final Button b2 = (Button)findViewById(R.id.iTestFragmentInnerButton);
if(b2 == null) { Log.d("MainActivity.java:", "b2 is null"); }
else { Log.d("MainActivity.java:", "b2 is NOT null"); }
fragmentButton.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
// do stuff here
}
});
}
}
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/iMainRootLinearLayoutContainer"
android:orientation="vertical"
>
<Button
android:id="#+id/iMainButton"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:text="Add fragment..."
/>
<LinearLayout
android:id="#+id/iMainInnerLLContainer"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:orientation="vertical"
>
<!-- Fragment goes here, can reference button if it is added here manually -->
</LinearLayout>
</LinearLayout>
TestFragment.java
public class TestFragment extends Fragment
{
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
return inflater.inflate(R.layout.ltestfragment, container, false);
}
}
ltestfragment.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:id="#+id/iTestFragmentOuterLinearLayout"
>
<Button
android:id="#+id/iTestFragmentInnerButton"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:text="This is my test fragment button."
/>
</LinearLayout>
I think I'm missing something very basic here and I would appreciate some insight on what that might be.
Thank you in advance!

I think you need to set up a textchangelistener in your fragment.
public class FragmentA extends Fragment {
TextChangeListener listener;
public interface TextChangeListener {
public void onTextChange(CharSequence newText);
}
public void setTextChangeListener(TextChangeListener listener) {
this.listener = listener;
}
Then, in your activity, set up the listener :
public class ActivityAB extends FragmentActivity {
FragmentA fragmentA;
FragmentB fragmentB;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_ab);
FragmentManager manager = getSupportFragmentManager();
fragmentA = (FragmentA) manager.findFragmentById(R.id.fragmentA);
fragmentB = (FragmentB) manager.findFragmentById(R.id.fragmentB);
fragmentA.setTextChangeListener(new TextChangeListener() {
#Override
public void onTextChange(CharSequence newText) {
fragmentB.updateTextValue(newText);
}
});
}
}

Implement an interface to listen to the events of a fragment from its activity.
Code in Fragment:-
public class TestFragment extends Fragment
{
public interface OnClickListener
{
public void onButtonClicked(<data type><data>);
}
b2.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
listener.onButtonClicked(<<pass some values here>>);
}
});
}
Code in Main:-
MainActivity extends FragmentActivity implements TestFragment.OnClickListener,
{
#Override
public void onButtonClicked(<<receive the pased data here>>) {
//do some stuff here with the received data after the button is clicked
}
}

Updating ui in a fragment

I can't seem to update the ui in one of my fragments, I'm not sure why. I have a main activity which should send some json to the fragment and update the UI with the data from the JSON object. I'm sending the json over successfully and I can log the data in the Fragment which I have sent over. I am just not able to update the textbox value in the UI.
In my mainactivity
MainPageFragment myFragment = new MainPageFragment();
SectionsPagerAdapter mSectionsPagerAdapter;
ViewPager mViewPager;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//Create adapter that will return a fragment for each section of app
mSectionsPagerAdapter = new SectionsPagerAdapter(getFragmentManager());
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
}
#Override
public void onSuccess(JSONObject user) {
//This seems to be all I need
myFragment.grabJSON(user);
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return 2;
}
#Override
public CharSequence getPageTitle (int position) {
return titles[position];
}
#Override
public Fragment getItem(int position) {
if (position == 1) {
return new PreferenceFragment() {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.layout.settings_preferances);
}
};
}
else {
return myFragment;
}
}
}
In my MainFragment.java
public void grabJSON(JSONObject object){
getActivity().runOnUiThread(new Runnable() {
#Override
public void run() {
TextView usernameTextView = (TextView) getView().findViewById(R.id.usernameview);
CharSequence val = usernameTextView.getText();
Log.d("value", val.toString());
usernameTextView.setText("NEW TEXT");//Set the Text
val = usernameTextView.getText();
Log.d("value", val.toString());
}
});
}
The fact that it sends the json is irrelevant, according to the log, my value of the textbox is changing but the actual UI is not changing.
I'm adding here the xml for the mainactivity
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<android.support.v4.view.PagerTabStrip
android:id="#+id/pager_header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="top"
android:textColor="#fff"/>
<FrameLayout
android:id="#+id/fragment_placeholder"
android:layout_width="fill_parent"
android:layout_height="fill_parent" ></FrameLayout>
</android.support.v4.view.ViewPager>
This has been updated with correct code, turns out I was defining the fragment twice
Thank you all,
Tom

Your fragment is getting added twice.
It's added via the layout XML file, and then you do a fragment transaction to add it aw well. Adding fragments via layout doesn't work as well as it should, so you should put in a placeholder view and then add the fragment via the fragment manager. That should clear everything up.

I'm guessing you dont add the fragment in the activity?
FragmentManager fragmentManager = getFragmentManager()
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
MainPageFragment fragment = new MainPageFragment ();
fragmentTransaction.add(R.id.fragment_container, fragment);
fragmentTransaction.commit();

How do I add a Fragment to an Activity with a programmatically created content view

I want to add a Fragment to an Activity that implements its layout programmatically. I looked over the Fragment documentation but there aren't many examples describing what I need. Here is the type of code I tried to write:
public class DebugExampleTwo extends Activity {
private ExampleTwoFragment mFragment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FrameLayout frame = new FrameLayout(this);
if (savedInstanceState == null) {
mFragment = new ExampleTwoFragment();
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.add(frame.getId(), mFragment).commit();
}
setContentView(frame);
}
}
...
public class ExampleTwoFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
Button button = new Button(getActivity());
button.setText("Hello There");
return button;
}
}
This code compiles but crashes at start, probably because my FragmentTransaction.add() is incorrect. What is the correct way to do this?

It turns out there's more than one problem with that code. A fragment cannot be declared that way, inside the same java file as the activity but not as a public inner class. The framework expects the fragment's constructor (with no parameters) to be public and visible. Moving the fragment into the Activity as an inner class, or creating a new java file for the fragment fixes that.
The second issue is that when you're adding a fragment this way, you must pass a reference to the fragment's containing view, and that view must have a custom id. Using the default id will crash the app. Here's the updated code:
public class DebugExampleTwo extends Activity {
private static final int CONTENT_VIEW_ID = 10101010;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FrameLayout frame = new FrameLayout(this);
frame.setId(CONTENT_VIEW_ID);
setContentView(frame, new LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
if (savedInstanceState == null) {
Fragment newFragment = new DebugExampleTwoFragment();
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.add(CONTENT_VIEW_ID, newFragment).commit();
}
}
public static class DebugExampleTwoFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
EditText v = new EditText(getActivity());
v.setText("Hello Fragment!");
return v;
}
}
}

Here is what I came up with after reading Tony Wong's comment:
public class DebugExampleTwo extends BaseActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addFragment(android.R.id.content,
new DebugExampleTwoFragment(),
DebugExampleTwoFragment.FRAGMENT_TAG);
}
}
...
public abstract class BaseActivity extends Activity {
protected void addFragment(#IdRes int containerViewId,
#NonNull Fragment fragment,
#NonNull String fragmentTag) {
getSupportFragmentManager()
.beginTransaction()
.add(containerViewId, fragment, fragmentTag)
.disallowAddToBackStack()
.commit();
}
protected void replaceFragment(#IdRes int containerViewId,
#NonNull Fragment fragment,
#NonNull String fragmentTag,
#Nullable String backStackStateName) {
getSupportFragmentManager()
.beginTransaction()
.replace(containerViewId, fragment, fragmentTag)
.addToBackStack(backStackStateName)
.commit();
}
}
...
public class DebugExampleTwoFragment extends Fragment {
public static final String FRAGMENT_TAG =
BuildConfig.APPLICATION_ID + ".DEBUG_EXAMPLE_TWO_FRAGMENT_TAG";
// ...
}
Kotlin
If you are using Kotlin make sure to take a look at what the Kotlin extensions by Google provide or just write your own.

public class Example1 extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
DemoFragment fragmentDemo = (DemoFragment)
getSupportFragmentManager().findFragmentById(R.id.frame_container);
//above part is to determine which fragment is in your frame_container
setFragment(fragmentDemo);
(OR)
setFragment(new TestFragment1());
}
// This could be moved into an abstract BaseActivity
// class for being re-used by several instances
protected void setFragment(Fragment fragment) {
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction =
fragmentManager.beginTransaction();
fragmentTransaction.replace(android.R.id.content, fragment);
fragmentTransaction.commit();
}
}
To add a fragment into a Activity or FramentActivity it requires a
Container. That container should be a "Framelayout", which can be
included in xml or else you can use the default container for that
like "android.R.id.content" to remove or replace a fragment in
Activity.
main.xml
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent" >
<!-- Framelayout to display Fragments -->
<FrameLayout
android:id="#+id/frame_container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<ImageView
android:id="#+id/imagenext"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_margin="16dp"
android:src="#drawable/next" />
</RelativeLayout>

After read all Answers I came up with elegant way:
public class MyActivity extends ActionBarActivity {
Fragment fragment ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FragmentManager fm = getSupportFragmentManager();
fragment = fm.findFragmentByTag("myFragmentTag");
if (fragment == null) {
FragmentTransaction ft = fm.beginTransaction();
fragment =new MyFragment();
ft.add(android.R.id.content,fragment,"myFragmentTag");
ft.commit();
}
}
basically you don't need to add a frameLayout as container of your fragment instead you can add straight the fragment into the android root View container
IMPORTANT: don't use replace fragment as most of the approach shown here, unless you don't mind to lose fragment variable instance state during onrecreation process.

For attaching fragment to an activity programmatically in Kotlin, you can look at the following code:
MainActivity.kt
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// create fragment instance
val fragment : FragmentName = FragmentName.newInstance()
// for passing data to fragment
val bundle = Bundle()
bundle.putString("data_to_be_passed", DATA)
fragment.arguments = bundle
// check is important to prevent activity from attaching the fragment if already its attached
if (savedInstanceState == null) {
supportFragmentManager
.beginTransaction()
.add(R.id.fragment_container, fragment, "fragment_name")
.commit()
}
}
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.MainActivity">
<FrameLayout
android:id="#+id/fragment_container"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
FragmentName.kt
class FragmentName : Fragment() {
companion object {
fun newInstance() = FragmentName()
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
// receiving the data passed from activity here
val data = arguments!!.getString("data_to_be_passed")
return view
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
}
}
If you are familiar with Extensions in Kotlin then you can even better this code by following this article.

public abstract class SingleFragmentActivity extends Activity {
public static final String FRAGMENT_TAG = "single";
private Fragment fragment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState == null) {
fragment = onCreateFragment();
getFragmentManager().beginTransaction()
.add(android.R.id.content, fragment, FRAGMENT_TAG)
.commit();
} else {
fragment = getFragmentManager().findFragmentByTag(FRAGMENT_TAG);
}
}
public abstract Fragment onCreateFragment();
public Fragment getFragment() {
return fragment;
}
}
use
public class ViewCatalogItemActivity extends SingleFragmentActivity {
#Override
public Fragment onCreateFragment() {
return new FragmentWorkShops();
}
}

For API level 17 or higher, View.generateViewId() will solve this problem. The utility method provides a unique id that is not used in build time.

This may help you
Defining a Fragment
create xml file for fragment view fragment_abc.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView" />
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
</LinearLayout>
create fragment ABCFragment.java
import androidx.fragment.app.Fragment;
public class FooFragment extends Fragment {
// The onCreateView method is called when Fragment should create its View object hierarchy,
// either dynamically or via XML layout inflation.
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle
savedInstanceState) {
// Defines the xml file for the fragment
return inflater.inflate(R.layout.fragment_abc, parent, false);
}
// This event is triggered soon after onCreateView().
// Any view setup should occur here. E.g., view lookups and attaching view listeners.
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
// Setup any handles to view objects here
// EditText etFoo = (EditText) view.findViewById(R.id.etFoo);
}
}
Add frameLayout in your activity
<FrameLayout
android:id="#+id/your_placeholder"
android:layout_width="match_parent"
android:layout_height="match_parent">
now in activity, add following method
protected void setFragment() {
// Begin the transaction
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
// Replace the contents of the container with the new fragment
ft.replace(R.id.fragment_container, new ABCFragment());
// or ft.add(R.id.your_placeholder, new ABCFragment());
// Complete the changes added above
ft.commit();
}
reference : https://guides.codepath.com/android/creating-and-using-fragments#defining-a-fragment