Fix nullness warning for MediaSource/MediaPeriod classes.

PiperOrigin-RevId: 249652301

library/core/src/main/java/com/google/android/exoplayer2/source/AbstractConcatenatedTimeline.java

@@ -19,6 +19,7 @@ import android.util.Pair;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Player;
 import com.google.android.exoplayer2.Timeline;
+import com.google.android.exoplayer2.util.Assertions;
 
 /**
  * Abstract base class for the concatenation of one or more {@link Timeline}s.
@@ -35,6 +36,7 @@ import com.google.android.exoplayer2.Timeline;
    * @param concatenatedUid UID of a period in a concatenated timeline.
    * @return UID of the child timeline this period belongs to.
    */
+  @SuppressWarnings("nullness:return.type.incompatible")
   public static Object getChildTimelineUidFromConcatenatedUid(Object concatenatedUid) {
     return ((Pair<?, ?>) concatenatedUid).first;
   }
@@ -45,6 +47,7 @@ import com.google.android.exoplayer2.Timeline;
    * @param concatenatedUid UID of a period in a concatenated timeline.
    * @return UID of the period in the child timeline.
    */
+  @SuppressWarnings("nullness:return.type.incompatible")
   public static Object getChildPeriodUidFromConcatenatedUid(Object concatenatedUid) {
     return ((Pair<?, ?>) concatenatedUid).second;
   }
@@ -220,7 +223,9 @@ import com.google.android.exoplayer2.Timeline;
         setIds);
     period.windowIndex += firstWindowIndexInChild;
     if (setIds) {
-      period.uid = getConcatenatedUid(getChildUidByChildIndex(childIndex), period.uid);
+      period.uid =
+          getConcatenatedUid(
+              getChildUidByChildIndex(childIndex), Assertions.checkNotNull(period.uid));
     }
     return period;
   }

library/core/src/main/java/com/google/android/exoplayer2/source/ClippingMediaPeriod.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.source;
 
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.FormatHolder;
@@ -25,6 +26,7 @@ import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /**
  * Wraps a {@link MediaPeriod} and clips its {@link SampleStream}s to provide a subsequence of their
@@ -37,8 +39,8 @@ public final class ClippingMediaPeriod implements MediaPeriod, MediaPeriod.Callb
    */
   public final MediaPeriod mediaPeriod;
 
-  private MediaPeriod.Callback callback;
+  @Nullable private MediaPeriod.Callback callback;
-  private ClippingSampleStream[] sampleStreams;
+  private @NullableType ClippingSampleStream[] sampleStreams;
   private long pendingInitialDiscontinuityPositionUs;
   /* package */ long startUs;
   /* package */ long endUs;
@@ -95,10 +97,14 @@ public final class ClippingMediaPeriod implements MediaPeriod, MediaPeriod.Callb
   }
 
   @Override
-  public long selectTracks(TrackSelection[] selections, boolean[] mayRetainStreamFlags,
+  public long selectTracks(
-      SampleStream[] streams, boolean[] streamResetFlags, long positionUs) {
+      @NullableType TrackSelection[] selections,
+      boolean[] mayRetainStreamFlags,
+      @NullableType SampleStream[] streams,
+      boolean[] streamResetFlags,
+      long positionUs) {
     sampleStreams = new ClippingSampleStream[streams.length];
-    SampleStream[] childStreams = new SampleStream[streams.length];
+    @NullableType SampleStream[] childStreams = new SampleStream[streams.length];
     for (int i = 0; i < streams.length; i++) {
       sampleStreams[i] = (ClippingSampleStream) streams[i];
       childStreams[i] = sampleStreams[i] != null ? sampleStreams[i].childStream : null;
@@ -119,7 +125,7 @@ public final class ClippingMediaPeriod implements MediaPeriod, MediaPeriod.Callb
     for (int i = 0; i < streams.length; i++) {
       if (childStreams[i] == null) {
         sampleStreams[i] = null;
-      } else if (streams[i] == null || sampleStreams[i].childStream != childStreams[i]) {
+      } else if (sampleStreams[i] == null || sampleStreams[i].childStream != childStreams[i]) {
         sampleStreams[i] = new ClippingSampleStream(childStreams[i]);
       }
       streams[i] = sampleStreams[i];
@@ -209,12 +215,12 @@ public final class ClippingMediaPeriod implements MediaPeriod, MediaPeriod.Callb
 
   @Override
   public void onPrepared(MediaPeriod mediaPeriod) {
-    callback.onPrepared(this);
+    Assertions.checkNotNull(callback).onPrepared(this);
   }
 
   @Override
   public void onContinueLoadingRequested(MediaPeriod source) {
-    callback.onContinueLoadingRequested(this);
+    Assertions.checkNotNull(callback).onContinueLoadingRequested(this);
   }
 
   /* package */ boolean isPendingInitialDiscontinuity() {
@@ -238,7 +244,8 @@ public final class ClippingMediaPeriod implements MediaPeriod, MediaPeriod.Callb
     }
   }
 
-  private static boolean shouldKeepInitialDiscontinuity(long startUs, TrackSelection[] selections) {
+  private static boolean shouldKeepInitialDiscontinuity(
+      long startUs, @NullableType TrackSelection[] selections) {
     // If the clipping start position is non-zero, the clipping sample streams will adjust
     // timestamps on buffers they read from the unclipped sample streams. These adjusted buffer
     // timestamps can be negative, because sample streams provide buffers starting at a key-frame,
@@ -300,7 +307,7 @@ public final class ClippingMediaPeriod implements MediaPeriod, MediaPeriod.Callb
       }
       int result = childStream.readData(formatHolder, buffer, requireFormat);
       if (result == C.RESULT_FORMAT_READ) {
-        Format format = formatHolder.format;
+        Format format = Assertions.checkNotNull(formatHolder.format);
         if (format.encoderDelay != 0 || format.encoderPadding != 0) {
           // Clear gapless playback metadata if the start/end points don't match the media.
           int encoderDelay = startUs != 0 ? 0 : format.encoderDelay;
@@ -328,7 +335,5 @@ public final class ClippingMediaPeriod implements MediaPeriod, MediaPeriod.Callb
       }
       return childStream.skipData(positionUs);
     }
-
   }
-
 }

library/core/src/main/java/com/google/android/exoplayer2/source/ClippingMediaSource.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.source;
 
+
 import androidx.annotation.IntDef;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
@@ -86,9 +87,9 @@ public final class ClippingMediaSource extends CompositeMediaSource<Void> {
   private final ArrayList<ClippingMediaPeriod> mediaPeriods;
   private final Timeline.Window window;
 
-  private @Nullable Object manifest;
+  @Nullable private Object manifest;
-  private ClippingTimeline clippingTimeline;
+  @Nullable private ClippingTimeline clippingTimeline;
-  private IllegalClippingException clippingError;
+  @Nullable private IllegalClippingException clippingError;
   private long periodStartUs;
   private long periodEndUs;
 
@@ -222,7 +223,7 @@ public final class ClippingMediaSource extends CompositeMediaSource<Void> {
     Assertions.checkState(mediaPeriods.remove(mediaPeriod));
     mediaSource.releasePeriod(((ClippingMediaPeriod) mediaPeriod).mediaPeriod);
     if (mediaPeriods.isEmpty() && !allowDynamicClippingUpdates) {
-      refreshClippedTimeline(clippingTimeline.timeline);
+      refreshClippedTimeline(Assertions.checkNotNull(clippingTimeline).timeline);
     }
   }
 

library/core/src/main/java/com/google/android/exoplayer2/source/DeferredMediaPeriod.java

@@ -15,6 +15,8 @@
  */
 package com.google.android.exoplayer2.source;
 
+import static com.google.android.exoplayer2.util.Util.castNonNull;
+
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.SeekParameters;
@@ -22,6 +24,7 @@ import com.google.android.exoplayer2.source.MediaSource.MediaPeriodId;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.Allocator;
 import java.io.IOException;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /**
  * Media period that wraps a media source and defers calling its {@link
@@ -47,10 +50,10 @@ public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callb
 
   private final Allocator allocator;
 
-  private MediaPeriod mediaPeriod;
+  @Nullable private MediaPeriod mediaPeriod;
-  private Callback callback;
+  @Nullable private Callback callback;
   private long preparePositionUs;
-  private @Nullable PrepareErrorListener listener;
+  @Nullable private PrepareErrorListener listener;
   private boolean notifiedPrepareError;
   private long preparePositionOverrideUs;
 
@@ -150,53 +153,57 @@ public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callb
 
   @Override
   public TrackGroupArray getTrackGroups() {
-    return mediaPeriod.getTrackGroups();
+    return castNonNull(mediaPeriod).getTrackGroups();
   }
 
   @Override
-  public long selectTracks(TrackSelection[] selections, boolean[] mayRetainStreamFlags,
+  public long selectTracks(
-      SampleStream[] streams, boolean[] streamResetFlags, long positionUs) {
+      @NullableType TrackSelection[] selections,
+      boolean[] mayRetainStreamFlags,
+      @NullableType SampleStream[] streams,
+      boolean[] streamResetFlags,
+      long positionUs) {
     if (preparePositionOverrideUs != C.TIME_UNSET && positionUs == preparePositionUs) {
       positionUs = preparePositionOverrideUs;
       preparePositionOverrideUs = C.TIME_UNSET;
     }
-    return mediaPeriod.selectTracks(selections, mayRetainStreamFlags, streams, streamResetFlags,
+    return castNonNull(mediaPeriod)
-        positionUs);
+        .selectTracks(selections, mayRetainStreamFlags, streams, streamResetFlags, positionUs);
   }
 
   @Override
   public void discardBuffer(long positionUs, boolean toKeyframe) {
-    mediaPeriod.discardBuffer(positionUs, toKeyframe);
+    castNonNull(mediaPeriod).discardBuffer(positionUs, toKeyframe);
   }
 
   @Override
   public long readDiscontinuity() {
-    return mediaPeriod.readDiscontinuity();
+    return castNonNull(mediaPeriod).readDiscontinuity();
   }
 
   @Override
   public long getBufferedPositionUs() {
-    return mediaPeriod.getBufferedPositionUs();
+    return castNonNull(mediaPeriod).getBufferedPositionUs();
   }
 
   @Override
   public long seekToUs(long positionUs) {
-    return mediaPeriod.seekToUs(positionUs);
+    return castNonNull(mediaPeriod).seekToUs(positionUs);
   }
 
   @Override
   public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
-    return mediaPeriod.getAdjustedSeekPositionUs(positionUs, seekParameters);
+    return castNonNull(mediaPeriod).getAdjustedSeekPositionUs(positionUs, seekParameters);
   }
 
   @Override
   public long getNextLoadPositionUs() {
-    return mediaPeriod.getNextLoadPositionUs();
+    return castNonNull(mediaPeriod).getNextLoadPositionUs();
   }
 
   @Override
   public void reevaluateBuffer(long positionUs) {
-    mediaPeriod.reevaluateBuffer(positionUs);
+    castNonNull(mediaPeriod).reevaluateBuffer(positionUs);
   }
 
   @Override
@@ -206,14 +213,14 @@ public final class DeferredMediaPeriod implements MediaPeriod, MediaPeriod.Callb
 
   @Override
   public void onContinueLoadingRequested(MediaPeriod source) {
-    callback.onContinueLoadingRequested(this);
+    castNonNull(callback).onContinueLoadingRequested(this);
   }
 
   // MediaPeriod.Callback implementation
 
   @Override
   public void onPrepared(MediaPeriod mediaPeriod) {
-    callback.onPrepared(this);
+    castNonNull(callback).onPrepared(this);
   }
 
   private long getPreparePositionWithOverride(long preparePositionUs) {

library/core/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaSource.java

@@ -242,8 +242,8 @@ public final class ExtractorMediaSource extends BaseMediaSource
       Uri uri,
       DataSource.Factory dataSourceFactory,
       ExtractorsFactory extractorsFactory,
-      Handler eventHandler,
+      @Nullable Handler eventHandler,
-      EventListener eventListener) {
+      @Nullable EventListener eventListener) {
     this(uri, dataSourceFactory, extractorsFactory, eventHandler, eventListener, null);
   }
 
@@ -264,9 +264,9 @@ public final class ExtractorMediaSource extends BaseMediaSource
       Uri uri,
       DataSource.Factory dataSourceFactory,
       ExtractorsFactory extractorsFactory,
-      Handler eventHandler,
+      @Nullable Handler eventHandler,
-      EventListener eventListener,
+      @Nullable EventListener eventListener,
-      String customCacheKey) {
+      @Nullable String customCacheKey) {
     this(
         uri,
         dataSourceFactory,
@@ -296,9 +296,9 @@ public final class ExtractorMediaSource extends BaseMediaSource
       Uri uri,
       DataSource.Factory dataSourceFactory,
       ExtractorsFactory extractorsFactory,
-      Handler eventHandler,
+      @Nullable Handler eventHandler,
-      EventListener eventListener,
+      @Nullable EventListener eventListener,
-      String customCacheKey,
+      @Nullable String customCacheKey,
       int continueLoadingCheckIntervalBytes) {
     this(
         uri,

library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaPeriod.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.source;
 
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
@@ -23,6 +24,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.IdentityHashMap;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /**
  * Merges multiple {@link MediaPeriod}s.
@@ -35,9 +37,8 @@ import java.util.IdentityHashMap;
   private final CompositeSequenceableLoaderFactory compositeSequenceableLoaderFactory;
   private final ArrayList<MediaPeriod> childrenPendingPreparation;
 
-  private Callback callback;
+  @Nullable private Callback callback;
-  private TrackGroupArray trackGroups;
+  @Nullable private TrackGroupArray trackGroups;
-
   private MediaPeriod[] enabledPeriods;
   private SequenceableLoader compositeSequenceableLoader;
 
@@ -49,6 +50,7 @@ import java.util.IdentityHashMap;
     compositeSequenceableLoader =
         compositeSequenceableLoaderFactory.createCompositeSequenceableLoader();
     streamPeriodIndices = new IdentityHashMap<>();
+    enabledPeriods = new MediaPeriod[0];
   }
 
   @Override
@@ -69,12 +71,16 @@ import java.util.IdentityHashMap;
 
   @Override
   public TrackGroupArray getTrackGroups() {
-    return trackGroups;
+    return Assertions.checkNotNull(trackGroups);
   }
 
   @Override
-  public long selectTracks(TrackSelection[] selections, boolean[] mayRetainStreamFlags,
+  public long selectTracks(
-      SampleStream[] streams, boolean[] streamResetFlags, long positionUs) {
+      @NullableType TrackSelection[] selections,
+      boolean[] mayRetainStreamFlags,
+      @NullableType SampleStream[] streams,
+      boolean[] streamResetFlags,
+      long positionUs) {
     // Map each selection and stream onto a child period index.
     int[] streamChildIndices = new int[selections.length];
     int[] selectionChildIndices = new int[selections.length];
@@ -94,9 +100,9 @@ import java.util.IdentityHashMap;
     }
     streamPeriodIndices.clear();
     // Select tracks for each child, copying the resulting streams back into a new streams array.
-    SampleStream[] newStreams = new SampleStream[selections.length];
+    @NullableType SampleStream[] newStreams = new SampleStream[selections.length];
-    SampleStream[] childStreams = new SampleStream[selections.length];
+    @NullableType SampleStream[] childStreams = new SampleStream[selections.length];
-    TrackSelection[] childSelections = new TrackSelection[selections.length];
+    @NullableType TrackSelection[] childSelections = new TrackSelection[selections.length];
     ArrayList<MediaPeriod> enabledPeriodsList = new ArrayList<>(periods.length);
     for (int i = 0; i < periods.length; i++) {
       for (int j = 0; j < selections.length; j++) {
@@ -114,10 +120,10 @@ import java.util.IdentityHashMap;
       for (int j = 0; j < selections.length; j++) {
         if (selectionChildIndices[j] == i) {
           // Assert that the child provided a stream for the selection.
-          Assertions.checkState(childStreams[j] != null);
+          SampleStream childStream = Assertions.checkNotNull(childStreams[j]);
           newStreams[j] = childStreams[j];
           periodEnabled = true;
-          streamPeriodIndices.put(childStreams[j], i);
+          streamPeriodIndices.put(childStream, i);
         } else if (streamChildIndices[j] == i) {
           // Assert that the child cleared any previous stream.
           Assertions.checkState(childStreams[j] == null);
@@ -208,7 +214,8 @@ import java.util.IdentityHashMap;
 
   @Override
   public long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters) {
-    return enabledPeriods[0].getAdjustedSeekPositionUs(positionUs, seekParameters);
+    MediaPeriod queryPeriod = enabledPeriods.length > 0 ? enabledPeriods[0] : periods[0];
+    return queryPeriod.getAdjustedSeekPositionUs(positionUs, seekParameters);
   }
 
   // MediaPeriod.Callback implementation
@@ -233,12 +240,12 @@ import java.util.IdentityHashMap;
       }
     }
     trackGroups = new TrackGroupArray(trackGroupArray);
-    callback.onPrepared(this);
+    Assertions.checkNotNull(callback).onPrepared(this);
   }
 
   @Override
   public void onContinueLoadingRequested(MediaPeriod ignored) {
-    callback.onContinueLoadingRequested(this);
+    Assertions.checkNotNull(callback).onContinueLoadingRequested(this);
   }
 
 }

library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaSource.java

@@ -71,9 +71,9 @@ public final class MergingMediaSource extends CompositeMediaSource<Integer> {
   private final ArrayList<MediaSource> pendingTimelineSources;
   private final CompositeSequenceableLoaderFactory compositeSequenceableLoaderFactory;
 
-  private Object primaryManifest;
+  @Nullable private Object primaryManifest;
   private int periodCount;
-  private IllegalMergeException mergeError;
+  @Nullable private IllegalMergeException mergeError;
 
   /**
    * @param mediaSources The {@link MediaSource}s to merge.
@@ -170,11 +170,13 @@ public final class MergingMediaSource extends CompositeMediaSource<Integer> {
   }
 
   @Override
-  protected @Nullable MediaPeriodId getMediaPeriodIdForChildMediaPeriodId(
+  @Nullable
+  protected MediaPeriodId getMediaPeriodIdForChildMediaPeriodId(
       Integer id, MediaPeriodId mediaPeriodId) {
     return id == 0 ? mediaPeriodId : null;
   }
 
+  @Nullable
   private IllegalMergeException checkTimelineMerges(Timeline timeline) {
     if (periodCount == PERIOD_COUNT_UNSET) {
       periodCount = timeline.getPeriodCount();

library/core/src/main/java/com/google/android/exoplayer2/source/SingleSampleMediaPeriod.java

@@ -31,11 +31,14 @@ import com.google.android.exoplayer2.upstream.Loader.LoadErrorAction;
 import com.google.android.exoplayer2.upstream.Loader.Loadable;
 import com.google.android.exoplayer2.upstream.StatsDataSource;
 import com.google.android.exoplayer2.upstream.TransferListener;
+import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /**
  * A {@link MediaPeriod} with a single sample.
@@ -64,8 +67,7 @@ import java.util.Arrays;
 
   /* package */ boolean notifiedReadingStarted;
   /* package */ boolean loadingFinished;
-  /* package */ boolean loadingSucceeded;
+  /* package */ byte @MonotonicNonNull [] sampleData;
-  /* package */ byte[] sampleData;
   /* package */ int sampleSize;
 
   public SingleSampleMediaPeriod(
@@ -112,8 +114,12 @@ import java.util.Arrays;
   }
 
   @Override
-  public long selectTracks(TrackSelection[] selections, boolean[] mayRetainStreamFlags,
+  public long selectTracks(
-      SampleStream[] streams, boolean[] streamResetFlags, long positionUs) {
+      @NullableType TrackSelection[] selections,
+      boolean[] mayRetainStreamFlags,
+      @NullableType SampleStream[] streams,
+      boolean[] streamResetFlags,
+      long positionUs) {
     for (int i = 0; i < selections.length; i++) {
       if (streams[i] != null && (selections[i] == null || !mayRetainStreamFlags[i])) {
         sampleStreams.remove(streams[i]);
@@ -204,9 +210,8 @@ import java.util.Arrays;
   public void onLoadCompleted(SourceLoadable loadable, long elapsedRealtimeMs,
       long loadDurationMs) {
     sampleSize = (int) loadable.dataSource.getBytesRead();
-    sampleData = loadable.sampleData;
+    sampleData = Assertions.checkNotNull(loadable.sampleData);
     loadingFinished = true;
-    loadingSucceeded = true;
     eventDispatcher.loadCompleted(
         loadable.dataSpec,
         loadable.dataSource.getLastOpenedUri(),
@@ -325,7 +330,7 @@ import java.util.Arrays;
         streamState = STREAM_STATE_SEND_SAMPLE;
         return C.RESULT_FORMAT_READ;
       } else if (loadingFinished) {
-        if (loadingSucceeded) {
+        if (sampleData != null) {
           buffer.addFlag(C.BUFFER_FLAG_KEY_FRAME);
           buffer.timeUs = 0;
           if (buffer.isFlagsOnly()) {
@@ -371,7 +376,7 @@ import java.util.Arrays;
 
     private final StatsDataSource dataSource;
 
-    private byte[] sampleData;
+    @Nullable private byte[] sampleData;
 
     public SourceLoadable(DataSpec dataSpec, DataSource dataSource) {
       this.dataSpec = dataSpec;

library/core/src/main/java/com/google/android/exoplayer2/source/ads/AdPlaybackState.java

@@ -18,12 +18,15 @@ package com.google.android.exoplayer2.source.ads;
 import android.net.Uri;
 import androidx.annotation.CheckResult;
 import androidx.annotation.IntDef;
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.util.Util;
 import java.lang.annotation.Documented;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.util.Arrays;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /**
  * Represents ad group times relative to the start of the media and information on the state and
@@ -45,9 +48,9 @@ public final class AdPlaybackState {
     /** The number of ads in the ad group, or {@link C#LENGTH_UNSET} if unknown. */
     public final int count;
     /** The URI of each ad in the ad group. */
-    public final Uri[] uris;
+    public final @NullableType Uri[] uris;
     /** The state of each ad in the ad group. */
-    public final @AdState int[] states;
+    @AdState public final int[] states;
     /** The durations of each ad in the ad group, in microseconds. */
     public final long[] durationsUs;
 
@@ -60,7 +63,8 @@ public final class AdPlaybackState {
           /* durationsUs= */ new long[0]);
     }
 
-    private AdGroup(int count, @AdState int[] states, Uri[] uris, long[] durationsUs) {
+    private AdGroup(
+        int count, @AdState int[] states, @NullableType Uri[] uris, long[] durationsUs) {
       Assertions.checkArgument(states.length == uris.length);
       this.count = count;
       this.states = states;
@@ -98,7 +102,7 @@ public final class AdPlaybackState {
     }
 
     @Override
-    public boolean equals(Object o) {
+    public boolean equals(@Nullable Object o) {
       if (this == o) {
         return true;
       }
@@ -130,7 +134,7 @@ public final class AdPlaybackState {
       Assertions.checkArgument(this.count == C.LENGTH_UNSET && states.length <= count);
       @AdState int[] states = copyStatesWithSpaceForAdCount(this.states, count);
       long[] durationsUs = copyDurationsUsWithSpaceForAdCount(this.durationsUs, count);
-      Uri[] uris = Arrays.copyOf(this.uris, count);
+      @NullableType Uri[] uris = Arrays.copyOf(this.uris, count);
       return new AdGroup(count, states, uris, durationsUs);
     }
 
@@ -151,7 +155,7 @@ public final class AdPlaybackState {
           this.durationsUs.length == states.length
               ? this.durationsUs
               : copyDurationsUsWithSpaceForAdCount(this.durationsUs, states.length);
-      Uri[] uris = Arrays.copyOf(this.uris, states.length);
+      @NullableType Uri[] uris = Arrays.copyOf(this.uris, states.length);
       uris[index] = uri;
       states[index] = AD_STATE_AVAILABLE;
       return new AdGroup(count, states, uris, durationsUs);
@@ -177,6 +181,7 @@ public final class AdPlaybackState {
           this.durationsUs.length == states.length
               ? this.durationsUs
               : copyDurationsUsWithSpaceForAdCount(this.durationsUs, states.length);
+      @NullableType
       Uri[] uris =
           this.uris.length == states.length ? this.uris : Arrays.copyOf(this.uris, states.length);
       states[index] = state;
@@ -362,7 +367,7 @@ public final class AdPlaybackState {
     if (adGroups[adGroupIndex].count == adCount) {
       return this;
     }
-    AdGroup[] adGroups = Arrays.copyOf(this.adGroups, this.adGroups.length);
+    AdGroup[] adGroups = Util.nullSafeArrayCopy(this.adGroups, this.adGroups.length);
     adGroups[adGroupIndex] = this.adGroups[adGroupIndex].withAdCount(adCount);
     return new AdPlaybackState(adGroupTimesUs, adGroups, adResumePositionUs, contentDurationUs);
   }
@@ -370,7 +375,7 @@ public final class AdPlaybackState {
   /** Returns an instance with the specified ad URI. */
   @CheckResult
   public AdPlaybackState withAdUri(int adGroupIndex, int adIndexInAdGroup, Uri uri) {
-    AdGroup[] adGroups = Arrays.copyOf(this.adGroups, this.adGroups.length);
+    AdGroup[] adGroups = Util.nullSafeArrayCopy(this.adGroups, this.adGroups.length);
     adGroups[adGroupIndex] = adGroups[adGroupIndex].withAdUri(uri, adIndexInAdGroup);
     return new AdPlaybackState(adGroupTimesUs, adGroups, adResumePositionUs, contentDurationUs);
   }
@@ -378,7 +383,7 @@ public final class AdPlaybackState {
   /** Returns an instance with the specified ad marked as played. */
   @CheckResult
   public AdPlaybackState withPlayedAd(int adGroupIndex, int adIndexInAdGroup) {
-    AdGroup[] adGroups = Arrays.copyOf(this.adGroups, this.adGroups.length);
+    AdGroup[] adGroups = Util.nullSafeArrayCopy(this.adGroups, this.adGroups.length);
     adGroups[adGroupIndex] = adGroups[adGroupIndex].withAdState(AD_STATE_PLAYED, adIndexInAdGroup);
     return new AdPlaybackState(adGroupTimesUs, adGroups, adResumePositionUs, contentDurationUs);
   }
@@ -386,7 +391,7 @@ public final class AdPlaybackState {
   /** Returns an instance with the specified ad marked as skipped. */
   @CheckResult
   public AdPlaybackState withSkippedAd(int adGroupIndex, int adIndexInAdGroup) {
-    AdGroup[] adGroups = Arrays.copyOf(this.adGroups, this.adGroups.length);
+    AdGroup[] adGroups = Util.nullSafeArrayCopy(this.adGroups, this.adGroups.length);
     adGroups[adGroupIndex] = adGroups[adGroupIndex].withAdState(AD_STATE_SKIPPED, adIndexInAdGroup);
     return new AdPlaybackState(adGroupTimesUs, adGroups, adResumePositionUs, contentDurationUs);
   }
@@ -394,7 +399,7 @@ public final class AdPlaybackState {
   /** Returns an instance with the specified ad marked as having a load error. */
   @CheckResult
   public AdPlaybackState withAdLoadError(int adGroupIndex, int adIndexInAdGroup) {
-    AdGroup[] adGroups = Arrays.copyOf(this.adGroups, this.adGroups.length);
+    AdGroup[] adGroups = Util.nullSafeArrayCopy(this.adGroups, this.adGroups.length);
     adGroups[adGroupIndex] = adGroups[adGroupIndex].withAdState(AD_STATE_ERROR, adIndexInAdGroup);
     return new AdPlaybackState(adGroupTimesUs, adGroups, adResumePositionUs, contentDurationUs);
   }
@@ -405,7 +410,7 @@ public final class AdPlaybackState {
    */
   @CheckResult
   public AdPlaybackState withSkippedAdGroup(int adGroupIndex) {
-    AdGroup[] adGroups = Arrays.copyOf(this.adGroups, this.adGroups.length);
+    AdGroup[] adGroups = Util.nullSafeArrayCopy(this.adGroups, this.adGroups.length);
     adGroups[adGroupIndex] = adGroups[adGroupIndex].withAllAdsSkipped();
     return new AdPlaybackState(adGroupTimesUs, adGroups, adResumePositionUs, contentDurationUs);
   }
@@ -413,7 +418,7 @@ public final class AdPlaybackState {
   /** Returns an instance with the specified ad durations, in microseconds. */
   @CheckResult
   public AdPlaybackState withAdDurationsUs(long[][] adDurationUs) {
-    AdGroup[] adGroups = Arrays.copyOf(this.adGroups, this.adGroups.length);
+    AdGroup[] adGroups = Util.nullSafeArrayCopy(this.adGroups, this.adGroups.length);
     for (int adGroupIndex = 0; adGroupIndex < adGroupCount; adGroupIndex++) {
       adGroups[adGroupIndex] = adGroups[adGroupIndex].withAdDurationsUs(adDurationUs[adGroupIndex]);
     }
@@ -441,7 +446,7 @@ public final class AdPlaybackState {
   }
 
   @Override
-  public boolean equals(Object o) {
+  public boolean equals(@Nullable Object o) {
     if (this == o) {
       return true;
     }

library/core/src/main/java/com/google/android/exoplayer2/source/ads/AdsMediaSource.java

@@ -47,6 +47,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /**
  * A {@link MediaSource} that inserts ads linearly with a provided content media source. This source
@@ -114,7 +115,7 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
      */
     public RuntimeException getRuntimeExceptionForUnexpected() {
       Assertions.checkState(type == TYPE_UNEXPECTED);
-      return (RuntimeException) getCause();
+      return (RuntimeException) Assertions.checkNotNull(getCause());
     }
   }
 
@@ -131,12 +132,12 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
   private final Timeline.Period period;
 
   // Accessed on the player thread.
-  private ComponentListener componentListener;
+  @Nullable private ComponentListener componentListener;
-  private Timeline contentTimeline;
+  @Nullable private Timeline contentTimeline;
-  private Object contentManifest;
+  @Nullable private Object contentManifest;
-  private AdPlaybackState adPlaybackState;
+  @Nullable private AdPlaybackState adPlaybackState;
-  private MediaSource[][] adGroupMediaSources;
+  private @NullableType MediaSource[][] adGroupMediaSources;
-  private Timeline[][] adGroupTimelines;
+  private @NullableType Timeline[][] adGroupTimelines;
 
   /**
    * Constructs a new source that inserts ads linearly with the content specified by {@code
@@ -202,24 +203,25 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
 
   @Override
   public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
+    AdPlaybackState adPlaybackState = Assertions.checkNotNull(this.adPlaybackState);
     if (adPlaybackState.adGroupCount > 0 && id.isAd()) {
       int adGroupIndex = id.adGroupIndex;
       int adIndexInAdGroup = id.adIndexInAdGroup;
-      Uri adUri = adPlaybackState.adGroups[adGroupIndex].uris[adIndexInAdGroup];
+      Uri adUri =
+          Assertions.checkNotNull(adPlaybackState.adGroups[adGroupIndex].uris[adIndexInAdGroup]);
       if (adGroupMediaSources[adGroupIndex].length <= adIndexInAdGroup) {
-        MediaSource adMediaSource = adMediaSourceFactory.createMediaSource(adUri);
+        int adCount = adIndexInAdGroup + 1;
-        int oldAdCount = adGroupMediaSources[adGroupIndex].length;
+        adGroupMediaSources[adGroupIndex] =
-        if (adIndexInAdGroup >= oldAdCount) {
+            Arrays.copyOf(adGroupMediaSources[adGroupIndex], adCount);
-          int adCount = adIndexInAdGroup + 1;
+        adGroupTimelines[adGroupIndex] = Arrays.copyOf(adGroupTimelines[adGroupIndex], adCount);
-          adGroupMediaSources[adGroupIndex] =
-              Arrays.copyOf(adGroupMediaSources[adGroupIndex], adCount);
-          adGroupTimelines[adGroupIndex] = Arrays.copyOf(adGroupTimelines[adGroupIndex], adCount);
-        }
-        adGroupMediaSources[adGroupIndex][adIndexInAdGroup] = adMediaSource;
-        deferredMediaPeriodByAdMediaSource.put(adMediaSource, new ArrayList<>());
-        prepareChildSource(id, adMediaSource);
       }
       MediaSource mediaSource = adGroupMediaSources[adGroupIndex][adIndexInAdGroup];
+      if (mediaSource == null) {
+        mediaSource = adMediaSourceFactory.createMediaSource(adUri);
+        adGroupMediaSources[adGroupIndex][adIndexInAdGroup] = mediaSource;
+        deferredMediaPeriodByAdMediaSource.put(mediaSource, new ArrayList<>());
+        prepareChildSource(id, mediaSource);
+      }
       DeferredMediaPeriod deferredMediaPeriod =
           new DeferredMediaPeriod(mediaSource, id, allocator, startPositionUs);
       deferredMediaPeriod.setPrepareErrorListener(
@@ -227,7 +229,8 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
       List<DeferredMediaPeriod> mediaPeriods = deferredMediaPeriodByAdMediaSource.get(mediaSource);
       if (mediaPeriods == null) {
         Object periodUid =
-            adGroupTimelines[adGroupIndex][adIndexInAdGroup].getUidOfPeriod(/* periodIndex= */ 0);
+            Assertions.checkNotNull(adGroupTimelines[adGroupIndex][adIndexInAdGroup])
+                .getUidOfPeriod(/* periodIndex= */ 0);
         MediaPeriodId adSourceMediaPeriodId = new MediaPeriodId(periodUid, id.windowSequenceNumber);
         deferredMediaPeriod.createPeriod(adSourceMediaPeriodId);
       } else {
@@ -258,7 +261,7 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
   @Override
   public void releaseSourceInternal() {
     super.releaseSourceInternal();
-    componentListener.release();
+    Assertions.checkNotNull(componentListener).release();
     componentListener = null;
     deferredMediaPeriodByAdMediaSource.clear();
     contentTimeline = null;
@@ -305,7 +308,7 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
     maybeUpdateSourceInfo();
   }
 
-  private void onContentSourceInfoRefreshed(Timeline timeline, Object manifest) {
+  private void onContentSourceInfoRefreshed(Timeline timeline, @Nullable Object manifest) {
     Assertions.checkArgument(timeline.getPeriodCount() == 1);
     contentTimeline = timeline;
     contentManifest = manifest;
@@ -330,6 +333,7 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
   }
 
   private void maybeUpdateSourceInfo() {
+    Timeline contentTimeline = this.contentTimeline;
     if (adPlaybackState != null && contentTimeline != null) {
       adPlaybackState = adPlaybackState.withAdDurationsUs(getAdDurations(adGroupTimelines, period));
       Timeline timeline =
@@ -340,7 +344,8 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
     }
   }
 
-  private static long[][] getAdDurations(Timeline[][] adTimelines, Timeline.Period period) {
+  private static long[][] getAdDurations(
+      @NullableType Timeline[][] adTimelines, Timeline.Period period) {
     long[][] adDurations = new long[adTimelines.length][];
     for (int i = 0; i < adTimelines.length; i++) {
       adDurations[i] = new long[adTimelines[i].length];