I have two activities

* MainActivity
* DetailActivity

My MainActivity.xml has AppBarLayout and Toolbar elements.
In Main Activity.java, I set the icon in toolbar using: 

```
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// setting icon
getSupportActionBar().setIcon(R.mipmap.ic_launcher);

```

This same line of code is not working for Detail activity.
Detail Activity has the toolbar by default. I can set the title in toolbar as well using:

```
getSupportActionBar().setTitle(String title);

```

But, I am unable to set Icon in Detail Activity using:

```
getSupportActionBar().setIcon(R.mipmap.ic_launcher);

```

**AndroidManifest.xml**

```
<?xml version="1.0" encoding="utf-8"?>

```

```
<uses-permission android:name="android.permission.INTERNET" />

<application
    android:name=".App"
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity
        android:name=".apod_main"
        android:label="@string/app_name"
        android:theme="@style/AppTheme.NoActionBar">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".apod_detail"></activity>
</application>

```

**Build Configs:**

**Android API** 26  

**Build Tools Version** 26.0.1