Why Android cannot find my onClick method inside fragment?

Question

So I have simple button in fragment, and I have an exception while clicking it. Fragmens shows up just fine.

Fragment code:

    public void onApplyButtonPressed(View view) {
        System.out.println("Apply button clicked");
//        viewToFilterData();
//        if (mListener != null) {
//            mListener.onFiltersApplyButtonPressed(userData);
//        }
    }

XML layout of fragment

<Button
    android:id="@+id/fragment_filters_apply_button"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:onClick="onApplyButtonPressed"
    android:text="@string/fragment_filters_apply_button" />

And how I attach my fragment in my main activity:

FiltersFragment filtersFragment = FiltersFragment.newInstance(userData);
getSupportFragmentManager().beginTransaction().add(R.id.activity_main_filters_page, filtersFragment).commit();

Can anyone see why this error happens?

 java.lang.IllegalStateException: Could not find method onApplyButtonPressed(View) in a parent or ancestor Context for android:onClick attribute defined on view class android.support.v7.widget.AppCompatButton with id 'fragment_filters_apply_button'
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:327)
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:284)
    at android.view.View.performClick(View.java:4438)
    at android.view.View$PerformClick.run(View.java:18422)
    at android.os.Handler.handleCallback(Handler.java:733)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:136)
    at android.app.ActivityThread.main(ActivityThread.java:5017)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
    at dalvik.system.NativeStart.main(Native Method)

PS: Using the same method as consumer to View.OnClickListener#onClick(View) works just fine. Something is wrong with method lookup in current context.

Answer 1

You can not handle the click event in your fragment by refer a method in XML. This only works if the method is implemented in your activity. I think it's because the activity ist the context of inflated view but the view doesn't have any reference to the fragment.

And this is why the exception is thrown because the method is missing in your activity.

You should use findViewById().setOnClickListener() inside your fragment.

Answer 2

The onClick attribute is intended to be used with Activities NOT Fragments . Looks like the using of OnClickListener is the simplest solution in your case. Another option (my favorite) is to use ButterKnife library which allows you to deal with that routine using annotations:

@OnClick(R.id.fragment_filters_apply_button)
void onApplyButtonClick(View view){
//your code
}

Answer 3

You inflate fragment from your MainActivity, so it puts in the main layout so the context for your xml is activity that instantiates your fragment. Make sure that you have onApplyButtonPressed(View v) method in your MainActivity.