Appcompat工具栏“android：title”属性不起作用

import android.support.v7.widget.Toolbar;
...
// Works fine
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle("My Title");

<!-- Doesn't work -->
<android.support.v7.widget.Toolbar
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="?attr/colorPrimary"
    android:minHeight="?attr/actionBarSize"
    android:title="@string/my_title"/>

您没有使用正确的属性.我认为 the Action Bar docs解释这个最好.

<menu xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:yourapp="http://schemas.android.com/apk/res-auto" >

    <item android:id="@+id/action_search"
          android:icon="@drawable/ic_action_search"
          android:title="@string/action_search"
          yourapp:showAsAction="ifRoom"  />
    ...
</menu>

Using XML attributes from the support library

Notice that the showAsAction attribute above uses a custom namespace defined in the tag. This is necessary when using any XML attributes defined by the support library,because these attributes do not exist in the Android framework on older devices. So you must use your own namespace as a prefix for all attributes defined by the support library.

换句话说,您需要将android：title更改为yourCustomPrefix：title

<YourRootViewGroup xmlns:app="http://schemas.android.com/apk/res/org.seeingpixels.photon"
    xmlns:android="http://schemas.android.com/apk/res/android"
    ... >

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimary"
        android:minHeight="?attr/actionBarSize"
        app:title="@string/my_title" />

</YourRootViewGroup>