Use lambdas in CacheManager

app/src/main/java/eu/kanade/mangafeed/data/caches/CacheManager.java

@@ -49,9 +49,7 @@ public class CacheManager {
     }
 
     public Observable<File> cacheImagesFromUrls(final List<String> imageUrls) {
-        return Observable.create(new Observable.OnSubscribe<File>() {
+        return Observable.create(subscriber -> {
-            @Override
-            public void call(Subscriber<? super File> subscriber) {
             try {
                 for (String imageUrl : imageUrls) {
                     if (!subscriber.isUnsubscribed()) {
@@ -62,7 +60,6 @@ public class CacheManager {
             } catch (Throwable e) {
                 subscriber.onError(e);
             }
-            }
         });
     }
 
@@ -75,16 +72,13 @@ public class CacheManager {
     }
 
     public Observable<Boolean> clearImageCache() {
-        return Observable.create(new Observable.OnSubscribe<Boolean>() {
+        return Observable.create(subscriber -> {
-            @Override
-            public void call(Subscriber<? super Boolean> subscriber) {
             try {
                 subscriber.onNext(clearImageCacheImpl());
                 subscriber.onCompleted();
             } catch (Throwable e) {
                 subscriber.onError(e);
             }
-            }
         });
     }
 
@@ -117,9 +111,7 @@ public class CacheManager {
     }
 
     public Observable<String> getImageUrlsFromDiskCache(final String chapterUrl) {
-        return Observable.create(new Observable.OnSubscribe<String>() {
+        return Observable.create(subscriber -> {
-            @Override
-            public void call(Subscriber<? super String> subscriber) {
             try {
                 String[] imageUrls = getImageUrlsFromDiskCacheImpl(chapterUrl);
 
@@ -132,7 +124,6 @@ public class CacheManager {
             } catch (Throwable e) {
                 subscriber.onError(e);
             }
-            }
         });
     }
 
@@ -154,15 +145,12 @@ public class CacheManager {
     }
 
     public Action0 putImageUrlsToDiskCache(final String chapterUrl, final List<String> imageUrls) {
-        return new Action0() {
+        return () -> {
-            @Override
-            public void call() {
             try {
                 putImageUrlsToDiskCacheImpl(chapterUrl, imageUrls);
             } catch (IOException e) {
                 // Do Nothing.
             }
-            }
         };
     }