Collapsingtoolbar in fragment not show/hide header when scrolling

Question

I replace fragment in a activity and in my fragment I need a CoordinatorLayout. Here is my code :

CoordinatorActivity class:

public class CoordinatorActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_coordinator);
        Fragment newFragment = new FragmentCoordinator();
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(R.id.fr_main, newFragment);
        transaction.addToBackStack(null);
        transaction.commit();
    }
}

activity_coordinator.xml file:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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"
    android:id="@+id/fr_main"
    tools:context="com.app.hoatv.CoordinatorActivity">
</FrameLayout>

FragmentCoordinator class:

public class FragmentCoordinator extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_coordinator, container, false);
    }
}

fragment_coordinator.xml file :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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="com.app.hoatv.CoordinatorActivity">
    <android.support.design.widget.CoordinatorLayout
        android:layout_height="match_parent"
        android:layout_width="match_parent">
        <android.support.design.widget.AppBarLayout
            android:layout_height="wrap_content"
            android:layout_width="match_parent"
            app:elevation="0dp"
            android:fitsSystemWindows="true"
            android:theme="@style/AppTheme">
            <include layout="@layout/layout_group_header"/>
        </android.support.design.widget.AppBarLayout>
        <android.support.v4.widget.NestedScrollView
            android:layout_height="match_parent"
            android:layout_width="match_parent"
            app:layout_behavior="@string/appbar_scrolling_view_behavior"
            android:fillViewport="true">
            <android.support.v7.widget.AppCompatTextView
                android:layout_height="1000dp"
                android:layout_width="match_parent"
                android:text="@string/lorem"
                android:background="@color/colorAccent"
                android:id="@+id/container"/>
        </android.support.v4.widget.NestedScrollView>
    </android.support.design.widget.CoordinatorLayout>
</LinearLayout>

layout_group_header.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="100dp"
    android:background="#a70000">

</LinearLayout>

but when I scrolling NestedScrollView layout_group_header.xml not show or hide. It always show in my fragment screen. What happened in my code? and How I can fix it?

Answer 1

What happened in my code? and How I can fix it?

There are few things which you should consider. First, you are opening a view(LinearLayout) inside AppBarLayout which there might be a Toolbar but that's not just the case.

First part: (Important one): The best idea and correct way of creating such layouts is to first, remove LinearLayout from the root of the fragment_coordinator layout then copy-paste the codes from fragment_coordinator to activity_coordinator. After that, use FrameLayout as the content's Container inside NestedScrollView.

Making Changes Part (As your requirements): After all, you can place codes anywhere you want in the main layout, for example, if you want the layout_group_header to be hidden after scrolling in the layout, you may wanna use layout_group_header codes inside fragment_coordinator which it will be a scrolling content. Othewise, you can use the codes inside CoordinatorLayout or anywhere instead of including it like that.

P.s: Design is completely seems to be wrong. Use first part which is an important part of creating such layouts. Note that there will be some changes inside java-kotlin sides too. (Changing layout address or etc)