// User pressed the stop button
public void StopMsg_button_action(View view){
    final EditText password_input = new EditText(this); // create an text input field
    password_input.setHint("Enter Password"); // put a hint in it
    password_input.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_PASSWORD); // change it to password type

    AlertDialog.Builder alertDialog = new Builder(this); // create an alert box
    alertDialog.setTitle("Enter Password"); // set the title
    alertDialog.setView(password_input);  // insert the password text field in the alert box
    alertDialog.setPositiveButton("OK", new DialogInterface.OnClickListener() { // define the 'OK' button
        public void onClick(DialogInterface dialog, int which) {
             String entered_password = password_input.getText().toString();
             if (entered_password.equals(my_password)) {
                locManager.removeUpdates(locListener); // stop listening for GPS coordinates
                startActivity(new Intent(Emergency_1Activity.this,Main_MenuActivity.class)); // go to main menu
             } else {
                 alert("Incorrect Password");
             }
        } 
    });
    alertDialog.setNeutralButton("Cancel", new DialogInterface.OnClickListener() { // define the 'Cancel' button
        public void onClick(DialogInterface dialog, int which) {

        } 
    });
    alertDialog.show(); // show the alert box
}

alertDialog.setNeutralButton("Cancel", new DialogInterface.OnClickListener() { // define the 'Cancel' button
    public void onClick(DialogInterface dialog, int which) {
        //Either of the following two lines should work.
        dialog.cancel();
        //dialog.dismiss();
    } 
});