Android Toolbar not showing when no layout_below in XML

Question

I have a weird issue concerning the Android Toolbar in Samsung Galaxy Tab 4. Maybe it's the OS (4.4.2) or the device itself. I am using the AppCompat-v7:23 library to display a Toolbar for pre-Lollipop devices.

Here is the XML code of my Activity where the Toolbar is displayed:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">

<include
    layout="@layout/appbar_content_top"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

And here is appbar_content_top:

<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:fitsSystemWindows="true"
tools:context=".CEMainActivity">

<FrameLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar_layout"
        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:layout_alignParentTop="true"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

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

    <FrameLayout
        android:id="@+id/content"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</FrameLayout>

As you can see, I did not put an android:layout_below attribute for @+id/content. That is one of my requirement. In my Activity, I get the Toolbar and set it as my supportActionToolbar.

toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
if (getSupportActionBar() != null) {
    Log.e("Viewer", "Toolbar is not null");
} else {
    Log.e("Viewer", "Toolbar is null");
}

The Toolbar displays for other devices. But in Galaxy Tab 4, the Toolbar is not displayed, even though the snippet above says that the Toolbar is not null.

Weirdly, if I add an android:layout_below attribute to @+id/content, the Toolbar will show in the Galaxy Tab 4.

Any clues on why this could be happening?? Thanks!

Answer 1

由于您使用的是appbarlayout，因此请使用coordinator布局而不是Framelayout作为appbar_content_top.xml的主视图组，coordinator的行为与framelayout相同，只是将其视为一个超级framelayout;），而layout_below还有一点可以与relativelayout一起正常使用，父视图组