content: package com.rxjava2.android.samples.ui.operators;
  
  import android.os.Bundle;
  import android.util.Log;
  import android.view.View;
  import android.widget.Button;
  import android.widget.TextView;
  
  import com.rxjava2.android.samples.R;
  import com.rxjava2.android.samples.utils.AppConstant;
  
  import java.util.concurrent.TimeUnit;
  
  import androidx.appcompat.app.AppCompatActivity;
  import io.reactivex.Observable;
  import io.reactivex.android.schedulers.AndroidSchedulers;
  import io.reactivex.disposables.CompositeDisposable;
  import io.reactivex.observers.DisposableObserver;
  import io.reactivex.schedulers.Schedulers;
  
  /**
   * Created by amitshekhar on 27/08/16.
   */
  public class IntervalExampleActivity extends AppCompatActivity {
  
      private static final String TAG = IntervalExampleActivity.class.getSimpleName();
      Button btn;
      TextView textView;
      private final CompositeDisposable disposables = new CompositeDisposable();
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_example);
          btn = findViewById(R.id.btn);
          textView = findViewById(R.id.textView);
  
          btn.setOnClickListener(new View.OnClickListener() {
              @Override
              public void onClick(View view) {
                  doSomeWork();
              }
          });
      }
  
      @Override
      protected void onDestroy() {
          super.onDestroy();
          disposables.clear(); // clearing it : do not emit after destroy
      }
  
      /*
       * simple example using interval to run task at an interval of 2 sec
       * which start immediately
       */
      private void doSomeWork() {
          disposables.add(getObservable()
                  // Run on a background thread
                  .subscribeOn(Schedulers.io())
                  // Be notified on the main thread
                  .observeOn(AndroidSchedulers.mainThread())
                  .subscribeWith(getObserver()));
      }
  
      private Observable<? extends Long> getObservable() {
          return Observable.interval(0, 2, TimeUnit.SECONDS);
      }
  
      private DisposableObserver<Long> getObserver() {
          return new DisposableObserver<Long>() {
  
              @Override
              public void onNext(Long value) {
                  textView.append(" onNext : value : " + value);
                  textView.append(AppConstant.LINE_SEPARATOR);
                  Log.d(TAG, " onNext : value : " + value);
              }
  
              @Override
              public void onError(Throwable e) {
                  textView.append(" onError : " + e.getMessage());
                  textView.append(AppConstant.LINE_SEPARATOR);
                  Log.d(TAG, " onError : " + e.getMessage());
              }
  
              @Override
              public void onComplete() {
                  textView.append(" onComplete");
                  textView.append(AppConstant.LINE_SEPARATOR);
                  Log.d(TAG, " onComplete");
              }
          };
      }
  
  
  }