Trying to generate and run apk

hello all: am trying to run my ionic app, to get apk file but i face this error:
[08:57:13] tslint: …Users/IBM/Documents/ionicproj/refresh/src/pages/product-detail/product-detail.ts, line: 15
All imports on this line are unused.

  L14:  import { TranslateService } from '@ngx-translate/core';
  L15:  import { CartPage } from '../cart/cart';
  L16:  import { ReviewsPage } from '../reviews/reviews';

[08:57:13] lint finished in 10.02 s
cordova.cmd build android --release
Android Studio project detected
JAVA_HOME=C:\Program Files\Java\jdk1.8.0_211
Could not find an installed version of Gradle either in Android Studio,
or on your system to install the gradle wrapper. Please include gradle
in your path, or install Android Studio
[ERROR] An error occurred while running subprocess cordova.

    cordova.cmd build android --release exited with exit code 1.

    Re-running this command with the --verbose flag may provide more information.

Remove those 3 imports if you are not using them.