title: How to start function in activity A after activity B finished?
body: <p>my app has 2 activities. The main activity is A. I call start B in A. (In B when user press Backbutton B's process will be killed by this code)</p>
  
  <pre><code>int pid = android.os.Process.myPid();
  android.os.Process.killProcess(pid);
  </code></pre>
  
  <p>my question is, how do I start a function in A when B is finished?</p>