title: Android Ui is not updating in thread
body: <p>In the Log works correctly but in setText does not change anything on the screen, and no error happens.</p>
  
  <pre><code>//within the onCreate method 
  myRef.child(fireUser.getUid()).addListenerForSingleValueEvent(new ValueEventListener() {
                  @Override
                  public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                      millis = Long.valueOf(dataSnapshot.child("millis").getValue().toString());
                      t1.run();
                  }
  
                  @Override
                  public void onCancelled(@NonNull DatabaseError databaseError) {
                      Intent i = new Intent(getApplicationContext(), SplashActivity.class);
                      startActivity(i);
                      finish();
                  }
              });
  
  //Out of the onCreate method
      Thread t1 = new Thread(){
              @Override
              public void run() {
                  try {
                      long i;
                      for(i=System.currentTimeMillis(); i &lt; millis+millis_wait; i=System.currentTimeMillis()) {
                          runOnUiThread(new Runnable() {
                              @Override
                              public void run() {
                                  long pr = (millis + millis_wait) - System.currentTimeMillis();
                                  tx_time.setText(""+pr);
                                  Log.i("TST", "" + pr);
                              }
                          });
                          Thread.sleep(1000);
                      }
                  } catch (InterruptedException e) {
                      e.printStackTrace();
                  }
              }
          };
  </code></pre>
  
  <p>What should I change?</p>
  
  <p>As I said, the code is working, the Log event is being called and executed perfectly, the only thing that does not happen is to update setText simply does not run, but also not from any errors.</p>