Butterknife does not work with Include tag

Question

I have a CoordinatorLayout where I have my Button:

<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="bottom|end">

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_marginBottom="16dp"
        android:layout_marginRight="16dp"
        android:src="@drawable/icon"
        app:fabSize="normal"/>

</android.support.design.widget.CoordinatorLayout>

And then I have the Activity xml where I include the Button:

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    ...

        <include
            android:id="@+id/fabHere"
            layout="@layout/fab_here"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

</LinearLayout>

And here I have a fragment with Butterknife:

public class MyFragment extends Fragment {
....
@BindView(R.id.fab) FloatingActionButton fab;


    @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            view = inflater.inflate(R.layout.my_fragment, container, false);
            ButterKnife.bind(this, view);

            return view;
    }
...
 }

But if I start the App this appears:
java.lang.IllegalStateException: Required view 'fab' with ID 2131624072 for field 'fabHere' was not found. If this view is optional add '@Nullable' (fields) or '@Optional' (methods) annotation.

I tried to add the '@Nullable' and '@Optional' annotations, but it does not work

Answer 1

Simply remove the id from the include tag and the binding will work, even for the fields in the included layout.

Answer 2

The MainActivity,

public MainActivity extends AppCompatActivity {
    // 1. First, we declare the layout that was included as a View objects.
    @BindView( R.id.layout_1 ) View layout_1;
    @BindView( R.id.layout_2 ) View layout_2;

    @Override
    protected void onCreate( Bundle savedInstanceState ) {
        super.onCreate( savedInstanceState );
        setContentView( R.layout.activity_main );

        // 2. In here, we bind the included layouts
        ButterKnife.bind( this );

        // 4. Then, we create objects of the type of the IncludedLayout.
        //      In this example the layout reuse the same layout twice, so, there are two
        //      IncludedLayouts.
        IncludedLayout includedLayout_1 = new IncludedLayout();
        IncludedLayout includedLayout_2 = new IncludedLayout();

        // 5. We bind the elements of the included layouts.
        ButterKnife.bind( includedLayout_1, layout_1 );
        ButterKnife.bind( includedLayout_2, layout_2 );

        // 6. And, finally, we use them.
        includedLayout_1.displayed_text.setText(  "Hello" );
        includedLayout_2.displayed_text.setText(  "Hey!" );
    }

    // 3. We create a static class that will be an container of the elements
    //     of the included layout. In here we declare the components that
    //     hold this. In this example, there is only one TextView.
    static class IncludedLayout {
        @BindView( R.id.displayed_text ) TextView displayed_text;
    }
}

The XML of the MainActivity:

<LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

        <include android:id="@+id/layout_1" layout="@layout/included_layout" />
        <include android:id="@+id/layout_2" layout="@layout/included_layout" />
</LinearLayout>

The XML of the Included Layout:

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/displayed_text"/>
</LinearLayout>

That's it!

Credit : Reference