title: How to Clear all previous activities~?
body: <p>Activity Flow in my app.</p>
  
  <blockquote>
    <p>WelcomeActivity -> SignInActivity -> SignUpActivity ->
    TabsActivity(this is main) -> ...</p>
  </blockquote>
  
  <hr>
  
  <p><img src="https://i.stack.imgur.com/rAEzy.jpg" alt="Activity Stack"></p>
  
  <hr>
  
  <p>I want to close all previous activities (Welcome, SignIn, SignUp) when start TabsActivity.</p>
  
  <p>I try several method...</p>
  
  <ol>
  <li><p>TabsActivity. clear task on launch=true  ? but not work (maybe)</p></li>
  <li><p>TabsActivity. launch mode = singleTask ? but not work</p></li>
  </ol>
  
  <p>But I do not want to "save 3 activities and call each activity.finish()"</p>
  
  <p>Depending on the situation, "available 2 or 4 activities not 3", or
  "I do not know What activities is in activity stack".</p>
  
  <hr>
  
  <p>I want to clear all previous activities, regadless of any situation.</p>
  
  <p>Help me :)</p>
  
  <p>Sorry my poor english... Thanks.</p>