Android crashes on calling FragmentTransaction Replace method? - java

What I am trying to do is to use only one Activity as a host for many fragments such as the activity will host only one fragment at a time and the fragments should attached to the activity in a certain order.
My Fragment code:
public class FirstFragment extends Fragment{
//some code here to instantiate FirstFragment here.
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.main, container, false);
Button button = (Button) view.findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
((MainActivity) getActivity()).onFirstFragmentFinished(position);
}
});
return view;
}
// Container Activity must implement this interface
public interface FirstFragmentListener {
public void onFirstFragmentFinished(int position);
}
}
Simply, in each fragment I have a button when pressed it will get the host activity and call the implemented method of FirstFragmentListener interface.
public class MainActivity extends AppCompatActivity implements FirstFragmentListener {
#Override
public void onCreateView(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTra = fragmentManager.beginTransaction();
fragmentTra .replace(R.id.main_layout, new FirstFragment());
fragmentTra.commit();
}
#Override
public void onFirstFragmentFinished(int position)
{
if(position == 1)
{
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTra = fragmentManager.beginTransaction();
fragmentTra .replace(R.id.main_layout, new SecondFragment());
fragmentTra.commit();
}
}
}
When the activity is created, always replace whatever inside this activity with FirstFragment layout.
When the FirstFragment finishes its work and the button on that fragment is pressed, it will call the implemented method of FirstFragment interface on this activity and then check the position for some value, if the condition is correct then go and replace FirstFragment with The SecondFragment instance.
The app is crashing when commit() method is called.

Use of your onFirstFragmentFinished is wrong. Look at official doc:
android-comunication-activity-ffragment
It is prefer to Override onAttach() method.

In Fragment you need View to bind with fragment like this :
public class FirstFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.main, container, false);
Button button = (Button) view.findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(position == 1){
SecondFragment secondFrag= new SecondFragment();
getActivity().getFragmentManager().beginTransaction()
.replace(R.id.main_layout, secondFrag)
.addToBackStack(null)
.commit();
}
}
});
return view;
}
}

I look at my stack trace and I found this exception:
com.example.exchange.msbexchange E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.exchange.msbexchange, PID: 17975
java.lang.RuntimeException: com.example.exchange.msbexchange.MainActivity#1e7d93b must implement OnFragmentInteractionListener
at com.example.exchange.msbexchange.CurrencyFragment.onAttach(CurrencyFragment.java:83)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1030)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1259)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1624)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6117)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
It is obviousely because my MainActivity does not implement the interface of the SecondFragment Class. I did not know this is mandatory for the fragments to work. I just need to implement the interface and now it is working.

you need implement your interface FirstFragmentListener in onAttach in fragment
FirstFragmentListener mCallback;
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
// This makes sure that the container activity has implemented
// the callback interface. If not, it throws an exception
try {
mCallback = (FirstFragmentListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnHeadlineSelectedListener");
}
}
then use it as you do on click or what ever you want

Where do you get position variable from? It seems that this variable does not have value...
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.main, container, false);
Button button = (Button) view.findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
((MainActivity) getActivity()).onFirstFragmentFinished(position);
}
});
return view;
}

Related

How to setOnclick Listener to image in fragment

I have image in my fragment. I want click on the picture and... for example change the fragment. I have found the same topic How to setOnclick Listener to button in fragment but ClickListner does not work.
I have tried make the same code in Activity and onClickListner is work, but in the frame it does not work.
Below my code in the Fragment.
public class Fragment2 extends Fragment {
ImageView imageView;
MyListner listner;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View getview = inflater.inflate(R.layout.fragment_2, container, false);
imageView = (ImageView) getview.findViewById(R.id.imageView1);
imageView.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
listner.callback();
}
});
return inflater.inflate(R.layout.fragment_2, container, false);
}
Below my interface
public interface MyListner {
public void callback();}
Below my MainActivity
public class MainActivity extends AppCompatActivity implements MyListner {
Fragment2 fragment2;
Fragment1 fragment1;
ImageView imageViewMain;
ImageView imageViewFragment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
fragment2 = new Fragment2();
setContentView(R.layout.activity_main);
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();//начало транзакции объекта
ft.replace(R.id.container, fragment2);
ft.addToBackStack(null);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
ft.commit();
}
#Override
public void callback() {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();//начало транзакции объекта
ft.replace(R.id.container, fragment1);
ft.addToBackStack(null);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
ft.commit();
}}
Please, let me know where is the problem?
It seems you are inflating your fragment's view twice. Instead of this you need to return the view which you have already inflated as a result of your onCreateView inside Fragment2.
Try changing
return inflater.inflate(R.layout.fragment_2, container, false);
to
return getview;

New fragment on button click from another fragment?

can anyone point me in the right direction and tell me what I'm doing wrong?
I have here a fragment with a button. When the button is pressed, it needs to replace the current fragment and load a new one. I've figured how to go from Fragment to Activity, and Activity to Fragment, just not Fragment to Fragment. I'm aware this question has been asked a few times but I'm just so new I couldn't figure it out myself.
public class FragmentName extends Fragment {
public FragmentName() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_name, container, false);
Button ID = (Button) rootView.findViewById(R.id.buttonID);
ID.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
FragmentName NAME = new FragmentName();
fragmentTransaction.replace(R.id.main_container, NAME);
fragmentTransaction.commit();
}
});
return rootView;
}
}
I think you are not initialising the FragmentManager. Without FragmentManager it is not possible to replace,update,create any fragment. Beacuse it is responsible replace or deleting any fragment. Hope this will help.
public class FragmentName extends Fragment {
public FragmentName() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_name, container, false);
Button ID = (Button) rootView.findViewById(R.id.buttonID);
ID.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
FragmentName NAME = new FragmentName();
fragmentTransaction.replace(R.id.main_container, NAME);
fragmentTransaction.commit();
}
});
return rootView;
}
}

Call a fragmentMethod from another fragment, but can't refer to them in parentFragmentActivity's View pager

I m new to android and i m having trouble with fragment communication, reading about it discovered the standard method of creating an interface and implementing it from the parentActivity which doesn't work in my case which is as follows.
I have an Activity named as ActivityA which extends fragment activity,in which i have a view pager for i want to keep two fragments namely fragmentA and fragmentB which should be swipable fragments.
fragmentA has a button which onClicked should make a change in fragmentB, to be precise on click it should add a string in the listView in fragmentA.
Now i have created the both the fragments's layouts as well as added the viewPAger to my FragmentActivity, they work great on swiping, the function is executed onButtonClick of fragmentA and logic works perfectly, after this is i want the changes to be reflected in fragmentB.
Using the interface method i can't find the reference to my fragment by id as it is added by viewPager to ActivityA
How do i do this??
help me out.
Stackoverflow says don't ask questions with out code so
Here is the Sample code
Activity A which has a virewPAger, need help how to get my fragment's Reference from the viewPager
public class ActivityA extends FragmentActivity implements FragmentA.Communicator
{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_A);
viewPager= (ViewPager) findViewById(R.id.pager);
fragmentManager=getSupportFragmentManager();
viewPager.setAdapter(new myAdapter(fragmentManager));
}
class myAdapter extends FragmentPagerAdapter{
public myAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
}
#Override
public Fragment getItem(int i) {
Fragment fragment = null;
switch (i){
case 0: fragment = new listOfIDsScanned();
break;
case 1: fragment = new displayCounter();
break;
default: //something witch won't crush the app
break;
}
return fragment;
}
#Override
public int getCount() {
return 2;
}
}
This is fragmentA , actual fragment name is something else just for simple representation calling it fragmentA, which has an interface Communicator to communicate between fragments
public class fragmentA extends android.support.v4.app.Fragment implements View.OnClickListener
{
TextView counter;
Button scanStudentID;
int count=0;
String name=null,rollNo=null;
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.display_counter,container,false);
}
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
scanStudentID= (Button) getActivity().findViewById(R.id.startScanning);
scanStudentID.setOnClickListener(this);
}
#Override
public void onClick(View v)
{
switch(v.getId()){
case R.id.startScanning:
startScanning();
break;
}
}
public void startScanning()
{
startActivityForResult(new Intent(getActivity(),Barcode.class),1);
}
public interface Communicator
{
// necessary methods
}
}
now finally fragmentB, in which methodToBeCalled(parameters) has to be invoked on the button click in fragementA
public class fragementB extends android.support.v4.app.Fragment
{
ListView listView;
ArrayList<String> rollNo= new ArrayList<>();
ArrayList<String> studentName= new ArrayList<>();
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_list_of_ids_scanned,container,false);
}
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
listView= (ListView) getActivity().findViewById(R.id.listView);
}
public void methodToBeCalled(String rollNo,String studentName)
{
if(!alreadyScanned(rollNo))
{
}
else
{
}
}
boolean alreadyScanned(String rollNo)
{
return true;
}
}

method does not override method from its superclass . Android Fragment

fragment1:
public class fragment1 extends Fragment implements View.OnClickListener {
ImageButton but, but1, but2;
ImageView view;
#Override << this one
public View OnCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View myView = inflater.inflate(R.layout.fragment1, null);
but = (ImageButton) myView.findViewById(R.id.imageButton11);
but.setOnClickListener(this);
but1 = (ImageButton) myView.findViewById(R.id.imageButton1);
but1.setOnClickListener(this);
but2 = (ImageButton) myView.findViewById(R.id.imageButton2);
but2.setOnClickListener(this);
return myView;
}
#Override
public void onClick(View v) {
main xxx = (main)getActivity();
switch (v.getId()) {
case R.id.imageButton11:
xxx.str="but1";
break;
..
}}
main:
Fragment frag1 = new fragment1();
fr1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
fTrans = getFragmentManager().beginTransaction();
fTrans.replace(R.id.frameLayout2, frag1);
fTrans.addToBackStack(null);
fTrans.commit();
}
});
method does not override method from its superclass in fragment1(first override)
but without "implemets View.OnClickListener" it works
Spelling mistake. Name the method onCreateView instead of OnCreateView.
I am not familiar with the android sdk but I think you need something like this
Fragment frag1 = new fragment1(){
#Override
public void onClick(View view) {
fTrans = getFragmentManager().beginTransaction();
fTrans.replace(R.id.frameLayout2, frag1);
fTrans.addToBackStack(null);
fTrans.commit();
}
};
return your inflated view
public View onCreateView(.....) {
...
...
return InputFragmentView;
}
and change OnCreateView to onCreateView.
you can tap ctrl+o to get it ready ^^
In my case I was not extending it from Fragment. Make sure you extend your fragment from Fragment class.
public class fragment1 extends Fragment implements View.OnClickListener {
#Override
/// public View onCreateView.......
}

No view found for id ... for fragment (Android application)

I am struggling with following error when I try to invoke fragment layout. Here is the code.
MainActivity;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void showFragOne(View view){
FragmentManager FM = getFragmentManager();
FragmentTransaction FT = FM.beginTransaction();
FT.add(R.layout.frag_one, new FragOne());
FT.commit();
}
}
showFragOne is called when button click on ativity_main layout.
frag_one is layout for FragOne Fragment
Fragment Class;
public class FragOne extends Fragment{
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View view = inflater.inflate(R.layout.frag_one, container, false);
return view;
}
}
Please help me in resolving this.
the way you are calling add() is wrong. The first parameter is the id of a ViewGroup that is going to host the fragment, not the layout of the fragment itself. For instance
FT.add(android.R.id.content, new FragOne());

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