Nativescript - Android disabling physical device back button

Question

I am trying to disabling the physical device back in android only in some screens. Trying the below code is not working. Any idea?

import { RouterExtensions } from "nativescript-angular";
  import * as application from "application";
  import { AndroidApplication, AndroidActivityBackPressedEventData } from "application";
  import { isAndroid } from "platform";

  export class ItemComponent implements OnInit {
    constructor(private router: Router) {}

    ngOnInit() {
      if (!isAndroid) {
        return;
      }
      application.android.on(AndroidApplication.activityBackPressedEvent, (data: AndroidActivityBackPressedEventData) => {

          data.cancel = true; // prevents default back button behavior

      });
    }
  }

Answer 1

@Override
public void onBackPressed() {
   if (!shouldAllowBack()) {
       doSomething();
   } else {
       super.onBackPressed();
   }
}

Answer 2

Add this code in your activity-

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
       // Your Code Here. Leave empty if you want nothing to happen on back press.

}

For more information visit this link.

Answer 3

Back button is controlled at Activity level, NativeScript uses one single Activity and all your pages / routes are fragments inside that.

So you don't have to call it on every page / component. Add the listener to your app component and check the router to know which page you are at and cancel the back event.

Answer 4

Use location and check if location consists the desired path(as mentioned in routing file) where you want to use your custom function.

import { Location } from '@angular/common';

constructor(private _location: Location ){}

if (application.android) {
            application.android.on(AndroidApplication.activityBackPressedEvent, (data: AndroidActivityBackPressedEventData) => {
                const path = this._location.path();

            console.log(`path i s--> ${path}`);
            switch (path) {
                case '/Screen 1':
                    data.cancel = true;
                    break;
                case '/Screen 2':
                    //do something else
                    break;
            });
        }