Validation on EditText in alertDialog
<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>