title: How to make Action Bar back button act as System back button in Android
body: <p>I have not seen a specific answer to this question so please do flag this as a duplicate if you can find the duplicate.</p>
  
  <p>I am wondering how does one make the back button of the Action Bar button act as the system back button. So when an action bar is displayed and there is the application icon in the top left with the back arrow, how does one make that act as the system (hardware sometimes) back button?
  Here is an example of the button I am talking about.</p>
  
  <p><img src="https://i.stack.imgur.com/AACDM.png" alt="enter image description here"></p>