title: starting existing android activity
body: <p>hi i have an application
  A is launcher activity from that i create B activity. From B i want to go back to A without deleting the instance of B(so no finish) then i want to create a new instance of B lets call it B2. And from A i want to be able to show B or B2 without recreating them.
  again i stress that B,B2 are the same class just diffrent instances.</p>
  
  <p>from B when i want to go to A i thought of using </p>
  
  <pre><code>Intent myIntent = new Intent(getBaseContext(), MainAct.class);
  myIntent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
  startActivity(myIntent);
  </code></pre>
  
  <p>but i think that its a mistake because it will clear other instances.
  what intent must i use in the cases?
  in c# windows application we would do B.hide();A.show(). then from A we could do
  A.hide(); B.SHOW() or B1.show();
  how can i do that in android please?</p>