diff --git a/app/src/main/java/org/schabi/newpipe/info_list/InfoListAdapter.java b/app/src/main/java/org/schabi/newpipe/info_list/InfoListAdapter.java
index 2978f9948..56bc63384 100644
--- a/app/src/main/java/org/schabi/newpipe/info_list/InfoListAdapter.java
+++ b/app/src/main/java/org/schabi/newpipe/info_list/InfoListAdapter.java
@@ -371,7 +371,7 @@ public class InfoListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolde
         };
     }
 
-    public class HFHolder extends RecyclerView.ViewHolder {
+    public static class HFHolder extends RecyclerView.ViewHolder {
         public View view;
 
         HFHolder(final View v) {
diff --git a/app/src/main/java/org/schabi/newpipe/player/playqueue/PlayQueueAdapter.java b/app/src/main/java/org/schabi/newpipe/player/playqueue/PlayQueueAdapter.java
index 3b42f2745..d063766c2 100644
--- a/app/src/main/java/org/schabi/newpipe/player/playqueue/PlayQueueAdapter.java
+++ b/app/src/main/java/org/schabi/newpipe/player/playqueue/PlayQueueAdapter.java
@@ -215,7 +215,7 @@ public class PlayQueueAdapter extends RecyclerView.Adapter<RecyclerView.ViewHold
         }
     }
 
-    public class HFHolder extends RecyclerView.ViewHolder {
+    public static class HFHolder extends RecyclerView.ViewHolder {
         public View view;
 
         public HFHolder(final View v) {
diff --git a/app/src/main/java/org/schabi/newpipe/streams/Mp4DashReader.java b/app/src/main/java/org/schabi/newpipe/streams/Mp4DashReader.java
index e1eb0e9e5..de327fba1 100644
--- a/app/src/main/java/org/schabi/newpipe/streams/Mp4DashReader.java
+++ b/app/src/main/java/org/schabi/newpipe/streams/Mp4DashReader.java
@@ -743,24 +743,24 @@ public class Mp4DashReader {
         return readFullBox(b);
     }
 
-    class Box {
+    static class Box {
         int type;
         long offset;
         long size;
     }
 
-    public class Moof {
+    public static class Moof {
         int mfhdSequenceNumber;
         public Traf traf;
     }
 
-    public class Traf {
+    public static class Traf {
         public Tfhd tfhd;
         long tfdt;
         public Trun trun;
     }
 
-    public class Tfhd {
+    public static class Tfhd {
         int bFlags;
         public int trackId;
         int defaultSampleDuration;
@@ -768,7 +768,7 @@ public class Mp4DashReader {
         int defaultSampleFlags;
     }
 
-    class TrunEntry {
+    static class TrunEntry {
         int sampleDuration;
         int sampleSize;
         int sampleFlags;
@@ -779,7 +779,7 @@ public class Mp4DashReader {
 
     }
 
-    public class Trun {
+    public static class Trun {
         public int chunkDuration;
         public int chunkSize;
 
@@ -837,7 +837,7 @@ public class Mp4DashReader {
         }
     }
 
-    public class Tkhd {
+    public static class Tkhd {
         int trackId;
         long duration;
         short bVolume;
@@ -848,25 +848,25 @@ public class Mp4DashReader {
         short bAlternateGroup;
     }
 
-    public class Trak {
+    public static class Trak {
         public Tkhd tkhd;
         public Elst edstElst;
         public Mdia mdia;
 
     }
 
-    class Mvhd {
+    static class Mvhd {
         long timeScale;
         long nextTrackId;
     }
 
-    class Moov {
+    static class Moov {
         Mvhd mvhd;
         Trak[] trak;
         Trex[] mvexTrex;
     }
 
-    public class Trex {
+    public static class Trex {
         private int trackId;
         int defaultSampleDescriptionIndex;
         int defaultSampleDuration;
@@ -874,37 +874,37 @@ public class Mp4DashReader {
         int defaultSampleFlags;
     }
 
-    public class Elst {
+    public static class Elst {
         public long mediaTime;
         public int bMediaRate;
     }
 
-    public class Mdia {
+    public static class Mdia {
         public int mdhdTimeScale;
         public byte[] mdhd;
         public Hdlr hdlr;
         public Minf minf;
     }
 
-    public class Hdlr {
+    public static class Hdlr {
         public int type;
         public int subType;
         public byte[] bReserved;
     }
 
-    public class Minf {
+    public static class Minf {
         public byte[] dinf;
         public byte[] stblStsd;
         public byte[] mhd;
     }
 
-    public class Mp4Track {
+    public static class Mp4Track {
         public TrackKind kind;
         public Trak trak;
         public Trex trex;
     }
 
-    public class Mp4DashChunk {
+    public static class Mp4DashChunk {
         public InputStream data;
         public Moof moof;
         private int i = 0;
@@ -936,7 +936,7 @@ public class Mp4DashReader {
         }
     }
 
-    public class Mp4DashSample {
+    public static class Mp4DashSample {
         public TrunEntry info;
         public byte[] data;
     }
diff --git a/app/src/main/java/org/schabi/newpipe/streams/Mp4FromDashWriter.java b/app/src/main/java/org/schabi/newpipe/streams/Mp4FromDashWriter.java
index 8f71c6934..5efffe118 100644
--- a/app/src/main/java/org/schabi/newpipe/streams/Mp4FromDashWriter.java
+++ b/app/src/main/java/org/schabi/newpipe/streams/Mp4FromDashWriter.java
@@ -897,7 +897,7 @@ public class Mp4FromDashWriter {
         return buffer.array();
     }
 
-    class TablesInfo {
+    static class TablesInfo {
         int stts;
         int stsc;
         int[] stscBEntries;
diff --git a/app/src/main/java/org/schabi/newpipe/streams/WebMReader.java b/app/src/main/java/org/schabi/newpipe/streams/WebMReader.java
index 7f7615426..8253ad6af 100644
--- a/app/src/main/java/org/schabi/newpipe/streams/WebMReader.java
+++ b/app/src/main/java/org/schabi/newpipe/streams/WebMReader.java
@@ -397,19 +397,19 @@ public class WebMReader {
         return obj;
     }
 
-    class Element {
+    static class Element {
         int type;
         long offset;
         long contentSize;
         long size;
     }
 
-    public class Info {
+    public static class Info {
         public long timecodeScale;
         public long duration;
     }
 
-    public class WebMTrack {
+    public static class WebMTrack {
         public long trackNumber;
         protected int trackType;
         public String codecId;
@@ -454,7 +454,7 @@ public class WebMReader {
         }
     }
 
-    public class SimpleBlock {
+    public static class SimpleBlock {
         public InputStream data;
         public boolean createdFromBlock;
 
diff --git a/app/src/main/java/org/schabi/newpipe/views/FocusAwareSeekBar.java b/app/src/main/java/org/schabi/newpipe/views/FocusAwareSeekBar.java
index a50d5a64c..8176a9aef 100644
--- a/app/src/main/java/org/schabi/newpipe/views/FocusAwareSeekBar.java
+++ b/app/src/main/java/org/schabi/newpipe/views/FocusAwareSeekBar.java
@@ -109,7 +109,7 @@ public final class FocusAwareSeekBar extends AppCompatSeekBar {
         }
     }
 
-    private final class NestedListener implements OnSeekBarChangeListener {
+    private static final class NestedListener implements OnSeekBarChangeListener {
         private final OnSeekBarChangeListener delegate;
 
         boolean isSeeking;
diff --git a/app/src/main/java/us/shandian/giga/service/DownloadManager.java b/app/src/main/java/us/shandian/giga/service/DownloadManager.java
index dc4d5701b..8359fce9a 100644
--- a/app/src/main/java/us/shandian/giga/service/DownloadManager.java
+++ b/app/src/main/java/us/shandian/giga/service/DownloadManager.java
@@ -686,7 +686,7 @@ public class DownloadManager {
         }
     }
 
-    public class MissionItem {
+    public static class MissionItem {
         public int special;
         public Mission mission;
 
diff --git a/app/src/main/java/us/shandian/giga/ui/adapter/MissionAdapter.java b/app/src/main/java/us/shandian/giga/ui/adapter/MissionAdapter.java
index 8bbef74c1..f3fb64a5d 100644
--- a/app/src/main/java/us/shandian/giga/ui/adapter/MissionAdapter.java
+++ b/app/src/main/java/us/shandian/giga/ui/adapter/MissionAdapter.java
@@ -976,7 +976,7 @@ public class MissionAdapter extends Adapter<ViewHolder> implements Handler.Callb
         }
     }
 
-    class ViewHolderHeader extends RecyclerView.ViewHolder {
+    static class ViewHolderHeader extends RecyclerView.ViewHolder {
         TextView header;
 
         ViewHolderHeader(View view) {