Hide toolbar (inside a AppBarLayout) in a specific fragment

Question

I newly started learning android. For the sake of developing a compatible version with Android Lollipop (API 21) and also android pre-lollipop devices (API15), I define two different styles. The first style supports ActionBar and the other one extends the property .NoActionBar which is needed for API21 and above. I think that I may misunderstood the appbar with toolbar and actionbar.

Additionaly, I use two fragments in my main activity. I wonder if there is a way that toolbar (which is inside the AppBarLayout in xml file) be hidden in specific fragment and shown in the other fragment.

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example">
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme">
        ...
        ...
    </application>
</manifest>

app_bar_main.xml

<android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay">
            <com.example.MyTextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textSize="22sp"
                android:layout_gravity="center"
                android:text="@string/app_name"/>
        </android.support.v7.widget.Toolbar>

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

styles.xml

<resources>
    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
        <item name="windowNoTitle">true</item>
    </style>
    <style name="AppTheme.NoActionBar">
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>
    </style>

    <style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />

    <style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />

</resources>

styles.xml (v21)

<resources>
    <style name="AppTheme.NoActionBar">
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>
        <item name="android:windowDrawsSystemBarBackgrounds">true</item>
        <item name="android:statusBarColor">@android:color/transparent</item>
    </style>
</resources>

Answer 1

The first style supports ActionBar and the other one extends the property .NoActionBar which is needed for API21 and above.

ActionBar is no longer recommended, so you can use Toolbar everywhere. Make your activity extend AppCompatActivity and set your toolbar as Actionbar using setSupportActionBar (Toolbar toolbar)