Android Support Library 27.1.1中fitsSystemWindows失效问题求助

Hey there, sorry to hear you're running into this frustrating issue with fitsSystemWindows after updating your Support Library from 27.0.2 to 27.1.1. I've seen this pop up a few times, so let's go through some common fixes that should get things working again.

1. Add fitsSystemWindows to Your AppBarLayout #

In many cases, the problem arises because the AppBarLayout isn't set to respect system window insets alongside the CoordinatorLayout. Try adding android:fitsSystemWindows="true" to your AppBarLayout—this ensures it properly adjusts to the status bar and navigation bar areas.

Here's how your updated layout might look:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 
    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"
    tools:context="...Activity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:fitsSystemWindows="true" <!-- Add this line -->
        android:theme="@style/AppTheme.AppBarOverlay">

        <!-- Your Toolbar or other AppBar content here -->
        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"/>

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

    <!-- Rest of your layout (NestedScrollView, RecyclerView, etc.) -->

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

2. Verify Your Theme's System Bar Settings #

The 27.1.1 update changed some behaviors around system bar backgrounds. Make sure your app theme has the correct settings to enable system bar drawing:

For AppCompat themes (most common), add these items to your style:

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <!-- Existing theme attributes -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    
    <!-- Add these lines -->
    <item name="windowDrawsSystemBarBackgrounds">true</item>
    <item name="android:statusBarColor">@android:color/transparent</item> <!-- Optional, if you want a transparent status bar -->
</style>

If you're using a native Android theme (non-AppCompat), use the android: prefix for the attributes:

<item name="android:windowDrawsSystemBarBackgrounds">true</item>

3. Manually Handle Window Insets with ViewCompat #

If the XML tweaks don't work, you can take control of the insets programmatically. This gives you full control over how the CoordinatorLayout and its children adjust to system windows.

Add this code to your Activity's onCreate method:

import android.support.v4.view.ViewCompat;
import android.support.v4.view.WindowInsetsCompat;
import android.support.design.widget.CoordinatorLayout;

// ...

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

    CoordinatorLayout coordinatorLayout = findViewById(R.id.your_coordinator_layout_id);
    ViewCompat.setOnApplyWindowInsetsListener(coordinatorLayout, (view, insets) -> {
        // Apply the system insets as padding to the CoordinatorLayout
        view.setPadding(
            insets.getSystemWindowInsetLeft(),
            insets.getSystemWindowInsetTop(),
            insets.getSystemWindowInsetRight(),
            insets.getSystemWindowInsetBottom()
        );
        // Pass the insets to child views if needed, or consume them here
        return insets.consumeSystemWindowInsets();
    });
}

4. Remove Conflicting fitsSystemWindows Attributes #

Check if any child views of your CoordinatorLayout (like NestedScrollView, RecyclerView, or other containers) have android:fitsSystemWindows="true" set. These can sometimes override the CoordinatorLayout's behavior, so try removing those attributes from child views and see if that fixes the issue.

If none of these solutions work, feel free to share your full layout XML and theme configuration—there might be a specific edge case we're missing.

内容的提问来源于stack exchange，提问作者Anton