diff --git a/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeSubscriptionExtractor.java b/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeSubscriptionExtractor.java
index aafb1cd18..6bd553a85 100644
--- a/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeSubscriptionExtractor.java
+++ b/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeSubscriptionExtractor.java
@@ -46,7 +46,8 @@ public class YoutubeSubscriptionExtractor extends SubscriptionExtractor {
     }
 
     @Override
-    public List<SubscriptionItem> fromInputStream(@Nonnull final InputStream contentInputStream, String contentType)
+    public List<SubscriptionItem> fromInputStream(@Nonnull final InputStream contentInputStream,
+                                                  @Nonnull final String contentType)
             throws ExtractionException {
         switch (contentType) {
             case "json":
@@ -100,27 +101,24 @@ public class YoutubeSubscriptionExtractor extends SubscriptionExtractor {
 
     public List<SubscriptionItem> fromZipInputStream(@Nonnull final InputStream contentInputStream)
             throws ExtractionException {
-        final ZipInputStream zipInputStream = new ZipInputStream(contentInputStream);
-
-        try {
+        try (final ZipInputStream zipInputStream = new ZipInputStream(contentInputStream)) {
             ZipEntry zipEntry;
             while ((zipEntry = zipInputStream.getNextEntry()) != null) {
                 if (zipEntry.getName().toLowerCase().endsWith(".csv")) {
                     try {
                         final List<SubscriptionItem> csvItems = fromCsvInputStream(zipInputStream);
 
-                        // Return it only if it has items (it exits early if it's the wrong file format)
-                        // Otherwise try the next file
+                        // Return it only if it has items (it exits early if it's the wrong file
+                        // format), otherwise try the next file
                         if (csvItems.size() > 0) {
                             return csvItems;
                         }
-                    } catch (ExtractionException e) {
+                    } catch (final ExtractionException e) {
                         // Ignore error and go to next file
-                        // (maybe log it?)
                     }
                 }
             }
-        } catch (IOException e) {
+        } catch (final IOException e) {
             throw new InvalidSourceException("Error reading contents of zip file", e);
         }
 
@@ -146,7 +144,7 @@ public class YoutubeSubscriptionExtractor extends SubscriptionExtractor {
         try (BufferedReader br = new BufferedReader(new InputStreamReader(contentInputStream))) {
             final List<SubscriptionItem> subscriptionItems = new ArrayList<>();
 
-            // Ignore header
+            // ignore header and skip first line
             currentLine = 1;
             line = br.readLine();
 
@@ -160,13 +158,13 @@ public class YoutubeSubscriptionExtractor extends SubscriptionExtractor {
                 }
 
                 // First comma
-                int i1 = line.indexOf(",");
+                final int i1 = line.indexOf(",");
                 if (i1 == -1) {
                     continue;
                 }
 
                 // Second comma
-                int i2 = line.indexOf(",", i1 + 1);
+                final int i2 = line.indexOf(",", i1 + 1);
                 if (i2 == -1) {
                     continue;
                 }
@@ -188,18 +186,20 @@ public class YoutubeSubscriptionExtractor extends SubscriptionExtractor {
                 // Channel title from third entry
                 final String channelTitle = line.substring(i2 + 1, i3);
 
-                final SubscriptionItem newItem = new SubscriptionItem(service.getServiceId(), channelUrl, channelTitle);
+                final SubscriptionItem newItem
+                        = new SubscriptionItem(service.getServiceId(), channelUrl, channelTitle);
                 subscriptionItems.add(newItem);
             }
 
             return subscriptionItems;
-        } catch (IOException e) {
+        } catch (final IOException e) {
             if (line == null) {
                 line = "<null>";
             } else if (line.length() > 10) {
                 line = line.substring(0, 10) + "...";
             }
-            throw new InvalidSourceException("Error reading CSV file, line = '" + line + "', line number = " + currentLine);
+            throw new InvalidSourceException("Error reading CSV file on line = \"" + line
+                    + "\", line number = " + currentLine, e);
         }
     }
 }
diff --git a/extractor/src/main/java/org/schabi/newpipe/extractor/subscription/SubscriptionExtractor.java b/extractor/src/main/java/org/schabi/newpipe/extractor/subscription/SubscriptionExtractor.java
index b2a2d75ef..cc223630f 100644
--- a/extractor/src/main/java/org/schabi/newpipe/extractor/subscription/SubscriptionExtractor.java
+++ b/extractor/src/main/java/org/schabi/newpipe/extractor/subscription/SubscriptionExtractor.java
@@ -63,8 +63,10 @@ public abstract class SubscriptionExtractor {
      *
      * @throws InvalidSourceException when the channelUrl doesn't exist or is invalid
      */
-    public List<SubscriptionItem> fromChannelUrl(String channelUrl) throws IOException, ExtractionException {
-        throw new UnsupportedOperationException("Service " + service.getServiceInfo().getName() + " doesn't support extracting from a channel url");
+    public List<SubscriptionItem> fromChannelUrl(final String channelUrl)
+            throws IOException, ExtractionException {
+        throw new UnsupportedOperationException("Service " + service.getServiceInfo().getName()
+                + " doesn't support extracting from a channel url");
     }
 
     /**
@@ -83,7 +85,8 @@ public abstract class SubscriptionExtractor {
      *
      * @throws InvalidSourceException when the content read from the InputStream is invalid and can not be parsed
      */
-    public List<SubscriptionItem> fromInputStream(@Nonnull final InputStream contentInputStream, String contentType)
+    public List<SubscriptionItem> fromInputStream(@Nonnull final InputStream contentInputStream,
+                                                  @Nonnull final String contentType)
             throws ExtractionException {
         throw new UnsupportedOperationException("Service " + service.getServiceInfo().getName()
                 + " doesn't support extracting from an InputStream");