BottomAppBar添加选项菜单后导航图标未垂直居中问题求助

Hey there, I've run into this exact navigation icon alignment issue with android.support.design.bottomappbar.BottomAppBar before—super frustrating when the icon shifts left after adding menu items! Here are a few tested solutions that should fix it:

1. Force Vertical Centering via Code #

You can directly target the navigation icon's view and adjust its layout parameters to enforce vertical centering, even after the menu loads:

Kotlin Code: #

val navigationIconView = bottomAppBar.findViewById<View>(com.google.android.material.R.id.navigation_icon)
val params = navigationIconView.layoutParams as ViewGroup.MarginLayoutParams
params.gravity = Gravity.CENTER_VERTICAL
navigationIconView.layoutParams = params

Java Code: #

View navigationIconView = bottomAppBar.findViewById(com.google.android.material.R.id.navigation_icon);
ViewGroup.MarginLayoutParams params = (ViewGroup.MarginLayoutParams) navigationIconView.getLayoutParams();
params.gravity = Gravity.CENTER_VERTICAL;
navigationIconView.setLayoutParams(params);

Run this code right after you inflate your menu (inside onCreateOptionsMenu or after calling inflateMenu() on the BottomAppBar).

2. Adjust Menu Item Display Behavior #

If your menu items are set to showAsAction="always", they might be taking up too much horizontal space and pushing the navigation icon out of alignment. Try modifying your menu XML to use showAsAction="ifRoom" instead for non-critical items:

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/action_search"
        android:title="Search"
        app:showAsAction="ifRoom"/> <!-- Use ifRoom instead of always -->
</menu>

This prevents the menu items from forcing the navigation icon's container to shrink unexpectedly.

3. Update Material Components Library #

Older versions of the Material Components library had layout bugs with BottomAppBar's navigation icon alignment. Make sure you're using the latest stable version in your build.gradle (Module level):

dependencies {
    implementation 'com.google.android.material:material:1.11.0' // Or newer
}

Upgrading often resolves subtle layout glitches like this one.

4. Check Navigation Icon Drawable Dimensions #

Sometimes the issue is with the navigation icon itself—if it has uneven padding or an odd aspect ratio, it might shift when the menu loads. Try using a drawable with consistent dimensions, or add explicit padding to the icon via XML:

<android.support.design.bottomappbar.BottomAppBar
    android:id="@+id/bottom_app_bar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:navigationIcon="@drawable/ic_menu_24dp" <!-- Ensure this drawable is properly sized -->
    app:paddingStart="8dp"
    app:paddingEnd="8dp"/>

Why This Happens #

Under the hood, the BottomAppBar uses a linear layout to arrange the navigation icon, menu items, and FAB (if present). When menu items are added, the layout recalculates weights and positions—older implementations didn't properly preserve the navigation icon's vertical alignment in this scenario.

内容的提问来源于stack exchange，提问作者Neeraj Kumar