Use List.isEmpty()

extractor/src/main/java/org/schabi/newpipe/extractor/downloader/Response.java

@@ -69,10 +69,8 @@ public class Response {
     public String getHeader(String name) {
         for (Map.Entry<String, List<String>> headerEntry : responseHeaders.entrySet()) {
             final String key = headerEntry.getKey();
-            if (key != null && key.equalsIgnoreCase(name)) {
+            if (key != null && key.equalsIgnoreCase(name) && !headerEntry.getValue().isEmpty()) {
-                if (headerEntry.getValue().size() > 0) {
+                return headerEntry.getValue().get(0);
-                    return headerEntry.getValue().get(0);
-                }
             }
         }
 

extractor/src/main/java/org/schabi/newpipe/extractor/playlist/PlaylistInfo.java

@@ -106,7 +106,7 @@ public class PlaylistInfo extends ListInfo<StreamInfoItem> {
             info.addError(e);
         }
         // do not fail if everything but the uploader infos could be collected
-        if (uploaderParsingErrors.size() > 0 &&
+        if (!uploaderParsingErrors.isEmpty() &&
                 (!info.getErrors().isEmpty() || uploaderParsingErrors.size() < 3)) {
             info.addAllErrors(uploaderParsingErrors);
         }

extractor/src/main/java/org/schabi/newpipe/extractor/services/bandcamp/extractors/BandcampSearchExtractor.java

@@ -87,7 +87,7 @@ public class BandcampSearchExtractor extends SearchExtractor {
 
         // Count pages
         final Elements pageLists = d.getElementsByClass("pagelist");
-        if (pageLists.size() == 0)
+        if (pageLists.isEmpty())
             return new InfoItemsPage<>(collector, null);
 
         final Elements pages = pageLists.first().getElementsByTag("li");
@@ -96,7 +96,7 @@ public class BandcampSearchExtractor extends SearchExtractor {
         int currentPage = -1;
         for (int i = 0; i < pages.size(); i++) {
             final Element pageElement = pages.get(i);
-            if (pageElement.getElementsByTag("span").size() > 0) {
+            if (!pageElement.getElementsByTag("span").isEmpty()) {
                 currentPage = i + 1;
                 break;
             }

extractor/src/main/java/org/schabi/newpipe/extractor/services/peertube/PeertubeService.java

@@ -63,7 +63,7 @@ public class PeertubeService extends StreamingService {
     public SearchExtractor getSearchExtractor(SearchQueryHandler queryHandler) {
         final List<String> contentFilters = queryHandler.getContentFilters();
         boolean external = false;
-        if (contentFilters.size() > 0 && contentFilters.get(0).startsWith("sepia_")) {
+        if (!contentFilters.isEmpty() && contentFilters.get(0).startsWith("sepia_")) {
             external = true;
         }
         return new PeertubeSearchExtractor(this, queryHandler, external);

extractor/src/main/java/org/schabi/newpipe/extractor/services/peertube/linkHandler/PeertubeSearchQueryHandlerFactory.java

@@ -24,7 +24,7 @@ public class PeertubeSearchQueryHandlerFactory extends SearchQueryHandlerFactory
     @Override
     public String getUrl(String searchString, List<String> contentFilters, String sortFilter) throws ParsingException {
         String baseUrl;
-        if (contentFilters.size() > 0 && contentFilters.get(0).startsWith("sepia_")) {
+        if (!contentFilters.isEmpty() && contentFilters.get(0).startsWith("sepia_")) {
             baseUrl = SEPIA_BASE_URL;
         } else {
             baseUrl = ServiceList.PeerTube.getBaseUrl();

extractor/src/main/java/org/schabi/newpipe/extractor/services/soundcloud/SoundcloudParsingHelper.java

@@ -89,7 +89,7 @@ public class SoundcloudParsingHelper {
             SoundcloudStreamExtractor e = (SoundcloudStreamExtractor) SoundCloud
                     .getStreamExtractor("https://soundcloud.com/liluzivert/do-what-i-want-produced-by-maaly-raw-don-cannon");
             e.fetchPage();
-            return e.getAudioStreams().size() >= 1;
+            return !e.getAudioStreams().isEmpty();
         } catch (Exception ignored) {
             // No need to throw an exception here. If something went wrong, the client_id is wrong
             return false;

extractor/src/main/java/org/schabi/newpipe/extractor/services/soundcloud/extractors/SoundcloudSearchExtractor.java

@@ -83,7 +83,7 @@ public class SoundcloudSearchExtractor extends SearchExtractor {
             throw new ParsingException("Could not parse json response", e);
         }
 
-        if (searchCollection.size() == 0) {
+        if (searchCollection.isEmpty()) {
             throw new SearchExtractor.NothingFoundException("Nothing found");
         }
     }

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/YoutubeService.java

@@ -123,7 +123,7 @@ public class YoutubeService extends StreamingService {
     public SearchExtractor getSearchExtractor(SearchQueryHandler query) {
         final List<String> contentFilters = query.getContentFilters();
 
-        if (contentFilters.size() > 0 && contentFilters.get(0).startsWith("music_")) {
+        if (!contentFilters.isEmpty() && contentFilters.get(0).startsWith("music_")) {
             return new YoutubeMusicSearchExtractor(this, query);
         } else {
             return new YoutubeSearchExtractor(this, query);

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/linkHandler/YoutubeSearchQueryHandlerFactory.java

@@ -32,7 +32,7 @@ public class YoutubeSearchQueryHandlerFactory extends SearchQueryHandlerFactory
     @Override
     public String getUrl(String searchString, List<String> contentFilters, String sortFilter) throws ParsingException {
         try {
-            if (contentFilters.size() > 0) {
+            if (!contentFilters.isEmpty()) {
                 switch (contentFilters.get(0)) {
                     case ALL:
                     default: