title: android toolbar: how to go back to previous activity if back arrow is pressed
body: <p>I have an activity called <code>Place</code></p>
  
  <p>I come to <code>Place</code> activity from its previous activity called <code>City</code>.</p>
  
  <p>I have added back button to the toolbar in <code>Place</code> activity using the following code:</p>
  
  <pre><code>    Toolbar mToolbar = (Toolbar) findViewById(R.id.toolbar);
      setSupportActionBar(mToolbar);
      getSupportActionBar().setDisplayHomeAsUpEnabled(true)
  </code></pre>
  
  <p>I want to set the back button to go back to <code>City</code> activity</p>
  
  <p>But <code>City</code> activity needs some parameters to be passed to it.</p>
  
  <p>So how to tell the back button to go to City activity, without need to pass the parameters to it. </p>