Android Fragment onClick button Method

Question

I m trying to invoke the method in my onClick  View v  XML  but does not work with Fragment  This is the error   01-17 12 38 36 840  E AndroidRuntime 4171   java lang IllegalStateException   Could not find a method insertIntoDb View  in the activity class main MainActivity  for onClick handler on view class android widget Button with id  btn conferma    Java code   public void insertIntoDb View v             XML    lt Button         android id   id btn conferma          style   android attr borderlessButtonStyle          android layout width  0 0dip          android layout height  45dp          android layout marginLeft  2dp          android layout weight  1 0          android background   drawable bottoni          android gravity  center horizontal center vertical          android onClick  insertIntoDb          android text  SALVA          android textColor   ffffff          android textSize  16sp    gt

User · Answer

Another option may be to have your fragment implement View.OnClickListener and override onClick(View v) within your fragment. If you need to have your fragment talk to the activity simply add an interface with desired method(s) and have the activity implement the interface and override its method(s).

public class FragName extends Fragment implements View.OnClickListener { 
    public FragmentCommunicator fComm;
    public ImageButton res1, res2;
    int c;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_test, container, false);
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            fComm = (FragmentCommunicator) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement FragmentCommunicator");
        }
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        res1 = (ImageButton) getActivity().findViewById(R.id.responseButton1);
        res1.setOnClickListener(this);
        res2 = (ImageButton) getActivity().findViewById(R.id.responseButton2);
        res2.setOnClickListener(this);
    }
    public void onClick(final View v) { //check for what button is pressed
            switch (v.getId()) {
                case R.id.responseButton1:
                  c *= fComm.fragmentContactActivity(2);
                  break;
                case R.id.responseButton2:
                  c *= fComm.fragmentContactActivity(4);
                  break;
                default:
                  c *= fComm.fragmentContactActivity(100);
                  break;
    }
    public interface FragmentCommunicator{
        public int fragmentContactActivity(int b);
    }



public class MainActivity extends FragmentActivity implements FragName.FragmentCommunicator{
    int a = 10;
    //variable a is update by fragment. ex. use to change textview or whatever else you'd like.

    public int fragmentContactActivity(int b) {
        //update info on activity here
        a += b;
        return a;
    }
}

http://developer.android.com/training/basics/firstapp/starting-activity.html http://developer.android.com/training/basics/fragments/communicating.html

User · Answer

Your activity must have  public void insertIntoDb View v             not Fragment    If you don t want the above in activity  initialize button in fragment and set listener to the same    lt Button     android id    id btn conferma       missing   Then    Override public View onCreateView LayoutInflater inflater  ViewGroup container          Bundle savedInstanceState        View view   inflater inflate R layout fragment rssitem detail      container  false      Button button    Button  view findViewById R id btn conferma      button setOnClickListener new OnClickListener                      Override              public void onClick View v                                    do something                            return view

User · Answer

If you want to use data binding you can follow this solution The following solution might be a better one to follow  the layout is in fragment my xml    lt data gt       lt variable         name  quot listener quot          type  quot my package MyListener quot    gt   lt  data gt    lt androidx constraintlayout widget ConstraintLayout     android layout width  quot match parent quot      android layout height  quot match parent quot  gt            lt Button         android id  quot   id moreTextView quot          android layout width  quot wrap content quot          android layout height  quot wrap content quot          android onClick  quot      - gt  listener onClick    quot          android text  quot  string login quot          app layout constraintTop toTopOf  quot parent quot          app layout constraintLeft toLeftOf  quot parent quot          app layout constraintRight toRightOf  quot parent quot    gt   lt  androidx constraintlayout widget ConstraintLayout gt    And the Fragment would be as follows class MyFragment   Fragment    MyListener       override fun onCreateView          inflater  LayoutInflater          container  ViewGroup           savedInstanceState  Bundle         View                return FragmentMyBinding inflate                  inflater                  container                  false               apply                   lifecycleOwner   viewLifecycleOwner                 listener   this MyFragment               root            override fun onClick             TODO  quot Not yet implemented quot             interface MyListener      fun onClick

User · Answer

Override public View onCreateView LayoutInflater inflater  ViewGroup container                           Bundle savedInstanceState         View view   inflater inflate R layout writeqrcode main  container  false          Inflate the layout for this fragment      txt name    TextView  view findViewById R id name       txt usranme    TextView  view findViewById R id surname       txt number    TextView  view findViewById R id number       txt province    TextView  view findViewById R id province       txt write    EditText  view findViewById R id editText write       txt show1    Button  view findViewById R id buttonShow1        txt show1 setOnClickListener new View OnClickListener              Override         public void onClick View v                Log e  Onclick   Onclick                 txt show1 setVisibility View INVISIBLE               txt name setVisibility View VISIBLE               txt usranme setVisibility View VISIBLE               txt number setVisibility View VISIBLE               txt province setVisibility View VISIBLE                         return view      You OK

User · Answer

This is not an issue  this is a design of Android   See here      You should design each fragment as a modular and reusable activity   component  That is  because each fragment defines its own layout and   its own behavior with its own lifecycle callbacks  you can include one   fragment in multiple activities  so you should design for reuse and   avoid directly manipulating one fragment from another fragment    A possible workaround would be to do something like this in your MainActivity   Fragment someFragment          onCreate etc instantiating your fragments  public void myClickMethod View v       someFragment myClickMethod v       and then in your Fragment class   public void myClickMethod View v       switch v getid               Your code here

User · Answer

The others have already said that methods in onClick are searched in activities  not fragments  Nevertheless  if you really want it  it is possible   Basically  each view has a tag  probably null   We set the root view s tag to the fragment that inflated that view  Then  it is easy to search the view parents and retrieve the fragment containing the clicked button  Now  we find out the method name and use reflection to call the same method from the retrieved fragment  Easy   in a class that extends Fragment    Override public View onCreateView LayoutInflater inflater  ViewGroup container  Bundle savedInstanceState        View rootView   inflater inflate R layout fragment id  container  false        OnClickFragments registerTagFragment rootView  this       lt                       return rootView     public void onButtonSomething View v        Log d            MyFragment onButtonSomething           whatever     all activities are derived from the same ButtonHandlingActivity   public class PageListActivity extends ButtonHandlingActivity   ButtonHandlingActivity java   public class ButtonHandlingActivity extends Activity        public void onButtonSomething View v            OnClickFragments invokeFragmentButtonHandlerNoExc v     or  if you want to handle exceptions          try               OnClickFragments invokeFragmentButtonHandler v             catch                It has to define methods for all xml onClick handlers   com example customandroid OnClickFragments java   package com example customandroid   import java lang reflect InvocationTargetException  import java lang reflect Method  import android app Fragment  import android view View   public abstract class OnClickFragments       public static class FragmentHolder           Fragment fragment          public FragmentHolder Fragment fragment                this fragment   fragment                      public static Fragment getTagFragment View view            for  View v   view  v    null  v    v getParent   instanceof View     View v getParent     null                Object tag   v getTag                if  tag    null  amp  amp  tag instanceof FragmentHolder                    return   FragmentHolder tag  fragment                                  return null            public static String getCallingMethodName int callsAbove            Exception e   new Exception            e fillInStackTrace            String methodName   e getStackTrace   callsAbove 1  getMethodName            return methodName            public static void invokeFragmentButtonHandler View v  int callsAbove  throws IllegalAccessException  IllegalArgumentException  InvocationTargetException  NoSuchMethodException           String methodName   getCallingMethodName callsAbove 1           Fragment f   OnClickFragments getTagFragment v           Method m   f getClass   getMethod methodName  new Class     View class             m invoke f  v             public static void invokeFragmentButtonHandler View v  throws IllegalAccessException  IllegalArgumentException  InvocationTargetException  NoSuchMethodException           invokeFragmentButtonHandler v 1             public static void invokeFragmentButtonHandlerNoExc View v            try               invokeFragmentButtonHandler v 1             catch  NoSuchMethodException e                e printStackTrace              catch  IllegalAccessException e                e printStackTrace              catch  IllegalArgumentException e                e printStackTrace              catch  InvocationTargetException e                e printStackTrace                        public static void registerTagFragment View rootView  Fragment fragment            rootView setTag new FragmentHolder fragment              And the next adventure will be proguard obfuscation     PS  It is of course up to you to design your application so that the data live in the Model rather than in Activities or Fragments  which are Controllers from the MVC  Model-View-Controller point of view   The View is what you define via xml  plus the custom view classes  if you define them  most people just reuse what already is   A rule of thumb  if some data definitely must survive the screen turn  they belong to Model

User · Answer

For Kotlin users   override fun onCreateView      inflater  LayoutInflater      container  ViewGroup        savedInstanceState  Bundle     View           Inflate the layout for this fragment     var myView   inflater inflate R layout fragment home  container  false      var btn test   myView btn test as Button     btn test setOnClickListener           textView text    hunny home fragment             return myView

[android] Android Fragment onClick button Method

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