title: How to add back button to custom toolbar layout on AppCompatActivity?
body: <p>I'm developing an android app. I'm using AppCompatActivity and would like to add back button to my custom toolbar. Here is the code of the toolbar:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
     &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:orientation="vertical" &gt;
  
         &lt;ImageView
             android:id="@+id/imageView"
             android:layout_width="match_parent"
             android:layout_height="54dp"
             android:layout_gravity="center_horizontal"
             android:src="@drawable/logo" /&gt;
  
         &lt;TextView android:id="@+id/title" android:layout_width="wrap_content"
             android:gravity="center_vertical" android:textSize="24px"
             android:textColor="#000000"
             android:layout_height="wrap_content"
             android:padding="9dip"
             android:layout_marginLeft="7dip"
             android:layout_marginRight="7dip"
             android:layout_marginStart="28dp"
             android:layout_centerVertical="true"
             android:layout_alignParentStart="true" /&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>Here is my activity code:</p>
  
  <pre><code>    super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_bookmarks);
  
      ActionBar actionBar = getSupportActionBar();
      actionBar.setHomeButtonEnabled(true);
      actionBar.setDisplayHomeAsUpEnabled(true);
  
      actionBar.setIcon(R.mipmap.ic_logo);
      actionBar.setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
      actionBar.setCustomView(R.layout.abs_layout);
      actionBar.setIcon(R.drawable.logo);
  
      //actionBar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE);
      ((TextView)findViewById(R.id.title)).setText(R.string.bookmarks);
  </code></pre>
  
  <p>What do I have to add that the back button will be displayed?</p>
  
  <p>Best,
  B.</p>