<?xml version="1.0" encoding="utf-8"?>
<layout>
<data>
<import type="android.view.View"/>
</data>

<androidx.coordinatorlayout.widget.CoordinatorLayout 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:fitsSystemWindows="true"
android:background="@color/white"
tools:context=".MainActivity3">

<com.google.android.material.appbar.AppBarLayout
android:id="@+id/app_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fitsSystemWindows="true"
android:background="@color/white">

<com.google.android.material.appbar.CollapsingToolbarLayout
android:id="@+id/toolbar_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
app:contentScrim="?attr/colorPrimary"
app:layout_scrollFlags="scroll|exitUntilCollapsed">


<androidx.appcompat.widget.AppCompatImageView
android:id="@+id/expandedImage"
android:layout_width="match_parent"
android:layout_height="300dp"
android:scaleType="centerCrop"
android:src="@mipmap/ic_launcher_round"
app:layout_collapseMode="parallax"
app:layout_collapseParallaxMultiplier="0.7" />

<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"/>

</com.google.android.material.appbar.CollapsingToolbarLayout>

</com.google.android.material.appbar.AppBarLayout>

<androidx.core.widget.NestedScrollView
app:layout_behavior="com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true">

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

<TextView
android:padding="16dp"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/lorem"
android:textColor="@color/black"
android:textSize="24dp"/>

</LinearLayout>



</androidx.core.widget.NestedScrollView>

<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="16dp"
app:layout_anchor="@id/app_bar"
app:layout_anchorGravity="bottom|end"
app:srcCompat="@android:drawable/ic_dialog_info" />

</androidx.coordinatorlayout.widget.CoordinatorLayout>
</layout>

import androidx.appcompat.app.AppCompatActivity;
import androidx.databinding.DataBindingUtil;

import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;

import com.example.mymap.databinding.ActivityMain3Binding;
import com.google.android.material.appbar.AppBarLayout;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;

public class MainActivity extends AppCompatActivity {

ActivityMain3Binding binding;
private Menu menu;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
binding = DataBindingUtil.setContentView(this,R.layout.activity_main3);


setSupportActionBar(binding.toolbar);

FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});


binding.appBar.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
boolean isShow = false;
int scrollRange = -1;

@Override
public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
if (scrollRange == -1) {
scrollRange = appBarLayout.getTotalScrollRange();
}
if (scrollRange + verticalOffset == 0) {
isShow = true;
showOption(R.id.action_info);
} else if (isShow) {
isShow = false;
hideOption(R.id.action_info);
}
}
});
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
this.menu = menu;
getMenuInflater().inflate(R.menu.menu_scrolling, menu);
hideOption(R.id.action_info);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();

//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
} else if (id == R.id.action_info) {
return true;
}

return super.onOptionsItemSelected(item);
}

private void hideOption(int id) {
MenuItem item = menu.findItem(id);
item.setVisible(false);
}

private void showOption(int id) {
MenuItem item = menu.findItem(id);
item.setVisible(true);
}
}

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<item
android:id="@+id/action_settings"
android:orderInCategory="100"
android:title="Setting"
app:showAsAction="never" />

<item
android:id="@+id/action_info"
android:orderInCategory="200"
android:title="info"
app:showAsAction="ifRoom"
android:icon="@android:drawable/ic_dialog_info"/>

</menu>