title: Validation on EditText in alertDialog
body: <p>I am trying to add empty field validations on <code>EditText</code> on <code>AlertDialog</code>. But even after field is empty error message is not getting displayed, instead <code>AlertDialog</code> is closing. But if conditions are working well as I'm not able to do post operations if any of the field is empty.</p>
  
  <p><strong>Here is my Java Sample code:</strong></p>
  
  <pre><code>public class TourActivity extends AppCompatActivity {
  
  private LayoutInflater inflater;
  private FloatingActionButton fab;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_tour);
      Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
      setSupportActionBar(toolbar);
      fab = (FloatingActionButton) findViewById(R.id.fab);
  
      fab.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View view) {
              inflater = TourActivity.this.getLayoutInflater();
              View content = inflater.inflate(R.layout.activity_add_new_trip, null);
              final EditText editEvent = (EditText) content.findViewById(R.id.edTxt_EventName);
              final EditText editStartDate = (EditText) content.findViewById(R.id.edTxt_EventSDate);
  
  
              AlertDialog.Builder builder = new AlertDialog.Builder(TourActivity.this);
              builder.setView(content)
                      .setTitle("Add Event")
                      .setPositiveButton(android.R.string.ok,
                              new DialogInterface.OnClickListener() {
                                  @Override
                                  public void onClick(DialogInterface dialog, int which) {
  
                                      editEvent.setError(null);
                                      editStartDate.setError(null);
  
                                      boolean cancel = false;
                                      View focusView = null;
  
                                      if (TextUtils.isEmpty(editEvent.getText().toString()))) {
                                          editEvent.setError("Please Enter Event Name.");
                                          return;
                                      }
  
                                      if (TextUtils.isEmpty(editStartDate.getText().toString())) {
                                          editStartDate.setError("Please Enter Event Start Date.");
                                          focusView = editStartDate;
                                          cancel = true;
                                      }
  
  
                                      if (cancel == true) {
                                          Snackbar.make(findViewById(android.R.id.content),
                                                  "Event Unsuccessful.", Snackbar.LENGTH_LONG)
                                                  .setActionTextColor(Color.RED)
                                                  .show();
                                          focusView.requestFocus();
                                      } else {
                                          // Some action here
                                      }
                                  }
                              })
                      .setNegativeButton(cancel, new DialogInterface.OnClickListener() {
  
                          @Override
                          public void onClick(DialogInterface dialog, int which) {
                              dialog.dismiss();
                          }
                      });
              AlertDialog dialog = builder.create();
              dialog.show();
          }
      });
  }
  }
  </code></pre>