diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 720343a..81faffd 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -12,11 +12,6 @@
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
         <activity android:name=".ui.SelectionActivity">
-            <intent-filter>
-                <action android:name="android.intent.action.MAIN" />
-
-                <category android:name="android.intent.category.LAUNCHER" />
-            </intent-filter>
         </activity>
         <activity
             android:name=".ui.OperatorsActivity"
@@ -47,7 +42,14 @@
             android:label="@string/zip" />
         <activity
             android:name=".ui.operators.DisposableExampleActivity"
-            android:label="@string/disposable" />
+            android:label="@string/disposable" >
+
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
         <activity
             android:name=".ui.operators.TakeExampleActivity"
             android:label="@string/take" />
diff --git a/app/src/main/java/com/rxjava2/android/samples/ui/operators/DisposableExampleActivity.java b/app/src/main/java/com/rxjava2/android/samples/ui/operators/DisposableExampleActivity.java
index 9e51b3c..959b2d4 100644
--- a/app/src/main/java/com/rxjava2/android/samples/ui/operators/DisposableExampleActivity.java
+++ b/app/src/main/java/com/rxjava2/android/samples/ui/operators/DisposableExampleActivity.java
@@ -10,13 +10,21 @@
 import com.rxjava2.android.samples.R;
 import com.rxjava2.android.samples.utils.AppConstant;
 
+import java.io.IOException;
 import java.util.concurrent.Callable;
+import java.util.concurrent.TimeUnit;
 
 import androidx.appcompat.app.AppCompatActivity;
+import io.reactivex.Completable;
 import io.reactivex.Observable;
+import io.reactivex.ObservableEmitter;
+import io.reactivex.ObservableOnSubscribe;
 import io.reactivex.ObservableSource;
 import io.reactivex.android.schedulers.AndroidSchedulers;
 import io.reactivex.disposables.CompositeDisposable;
+import io.reactivex.disposables.Disposable;
+import io.reactivex.functions.BiFunction;
+import io.reactivex.functions.Function;
 import io.reactivex.observers.DisposableObserver;
 import io.reactivex.schedulers.Schedulers;
 
@@ -55,10 +63,27 @@ protected void onDestroy() {
      * Example to understand how to use disposables.
      * disposables is cleared in onDestroy of this activity.
      */
+    static int number = 1;
     void doSomeWork() {
-        disposables.add(sampleObservable()
+        sampleObservable()
                 // Run on a background thread
                 .subscribeOn(Schedulers.io())
+                .retryWhen(new Function<Observable<Throwable>, ObservableSource<?>>() {
+                    @Override
+                    public ObservableSource<?> apply(Observable<Throwable> throwableObservable) throws Exception {
+                        Log.i(TAG, "apply exception0=============================");
+                        return throwableObservable.flatMap(new Function<Throwable, ObservableSource<?>>() {
+                            @Override
+                            public ObservableSource<?> apply(Throwable throwable) throws Exception {
+                                Log.i(TAG, "apply exception0--------------------");
+                                if (throwable instanceof IOException) {
+                                    return Observable.error(new IOException());
+                                }
+                                return Observable.just(number);
+                            }
+                        });
+                    }
+                })
                 // Be notified on the main thread
                 .observeOn(AndroidSchedulers.mainThread())
                 .subscribeWith(new DisposableObserver<String>() {
@@ -73,25 +98,33 @@ public void onComplete() {
                     public void onError(Throwable e) {
                         textView.append(" onError : " + e.getMessage());
                         textView.append(AppConstant.LINE_SEPARATOR);
-                        Log.d(TAG, " onError : " + e.getMessage());
+                        Log.d(TAG, " onError : " + e.getMessage() + "  :" + System.currentTimeMillis());
                     }
 
                     @Override
                     public void onNext(String value) {
-                        textView.append(" onNext : value : " + value);
+                        textView.append(" onNext : value : " + value + "  :" + System.currentTimeMillis());
                         textView.append(AppConstant.LINE_SEPARATOR);
                         Log.d(TAG, " onNext value : " + value);
                     }
-                }));
+                });
     }
 
     static Observable<String> sampleObservable() {
-        return Observable.defer(new Callable<ObservableSource<? extends String>>() {
+        return Observable.create(new ObservableOnSubscribe<String>() {
             @Override
-            public ObservableSource<? extends String> call() {
-                // Do some long running operation
-                SystemClock.sleep(2000);
-                return Observable.just("one", "two", "three", "four", "five");
+            public void subscribe(ObservableEmitter<String> emitter) throws Exception {
+                Log.i(TAG, "emit value:" + number);
+                Thread.sleep(1000);
+                emitter.onNext("Value-" + number);
+                if (number % 4 == 0) {
+                    emitter.onError(new IllegalArgumentException("Value:" + number));
+                } else if (number % 11 == 0) {
+                    emitter.onError(new IOException("ioexception"));
+                } else {
+                    emitter.onError(new Exception("test"));
+                }
+                number++;
             }
         });
     }