Analysis and Solution for Android Toolbar.setTitle Method Ineffectiveness

Problem Background and Phenomenon Description

In Android application development, when using the Toolbar component from the android-support-v7 library, developers often encounter a typical issue: after calling the Toolbar.setTitle method to set a title, the toolbar still displays the application name instead of the expected custom title. This phenomenon typically occurs during the process of setting the Toolbar as SupportActionBar.

Problem Code Analysis

The original problematic code is shown below:

public class MainActivity extends ActionBarActivity {
    Toolbar mActionBarToolbar;

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

        mActionBarToolbar = (Toolbar) findViewById(R.id.toolbar_actionbar);            
        mActionBarToolbar.setTitle("My title");
        setSupportActionBar(mActionBarToolbar);
    }
}

Corresponding layout file:

<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"
    android:orientation="vertical">

    <android.support.v7.widget.Toolbar            
        android:id="@+id/toolbar_actionbar"
        android:background="@null"
        android:layout_width="match_parent"
        android:layout_height="?actionBarSize"
        android:fitsSystemWindows="true" />

</LinearLayout>

With this implementation, despite calling mActionBarToolbar.setTitle("My title"), the toolbar still displays the application name, indicating that the setTitle method does not produce the expected effect.

Root Cause Analysis

The fundamental cause of the problem lies in the integration mechanism between Toolbar and ActionBar in Android Support Library. When the setSupportActionBar() method is called, the system converts the Toolbar into a SupportActionBar. During this process, the system checks the current title state of the Toolbar:

• If the Toolbar already has a non-empty title set, the system preserves this title
• If the Toolbar has no title set or the title is empty, the system uses the default window title (typically the application name)

The key point is that this check occurs at the moment setSupportActionBar() is called, not during subsequent title setting operations.

Solution 1: Using SupportActionBar to Set Title

The most direct and effective solution is to set the title through the SupportActionBar API after setting up the SupportActionBar:

mActionBarToolbar = (Toolbar) findViewById(R.id.toolbar_actionbar);            
setSupportActionBar(mActionBarToolbar);
getSupportActionBar().setTitle("My title");

This method works by first establishing the association between Toolbar and SupportActionBar, then managing the title through the standard ActionBar API. Since SupportActionBar is properly initialized, setting the title at this point ensures consistent title display.

Solution 2: Pre-setting Empty Title Strategy

Another solution is based on understanding the internal implementation of Support Library. You can set an empty title for the Toolbar before setting up SupportActionBar:

mActionBarToolbar = (Toolbar) findViewById(R.id.toolbar_actionbar);
mActionBarToolbar.setTitle("");
setSupportActionBar(mActionBarToolbar);

Then set the actual title when needed:

mActionBarToolbar.setTitle(title);

This method leverages implementation details of Support Library: when the Toolbar already has a title set (even if it's an empty string), the system respects this existing title state during SupportActionBar initialization, thus avoiding the use of default application name.

Style Configuration Considerations

When solving this problem, attention should also be paid to application theme configuration. The correct style configuration should use Theme.AppCompat.NoActionBar as the parent theme:

<style name="AppTheme" parent="Theme.AppCompat.NoActionBar">
    <item name="windowActionBar">false</item>
</style>

This ensures that the system does not create a default ActionBar, allowing the custom Toolbar to fully replace traditional ActionBar functionality.

Best Practice Recommendations

Based on the above analysis, the following best practices are recommended:

1. Always use getSupportActionBar().setTitle() to set titles after calling setSupportActionBar()
2. Ensure the application theme is correctly configured as a no-ActionBar theme
3. In complex application scenarios, consider using Toolbar's setTitle() method for dynamic title updates
4. Understand version differences in Support Library, as implementation details may vary across versions

Conclusion

The Android Toolbar title setting issue is a common development pitfall, rooted in the initialization timing during Toolbar and SupportActionBar integration. By understanding the internal mechanisms of Support Library, developers can choose appropriate solutions to ensure reliable title setting. Using SupportActionBar API for title management is recommended, as this approach not only solves the current problem but also maintains code standardization and maintainability.