diff --git a/libraries/common/src/main/java/androidx/media3/common/util/Util.java b/libraries/common/src/main/java/androidx/media3/common/util/Util.java
index 374e70f689..98d1113eda 100644
--- a/libraries/common/src/main/java/androidx/media3/common/util/Util.java
+++ b/libraries/common/src/main/java/androidx/media3/common/util/Util.java
@@ -69,6 +69,7 @@ import android.security.NetworkSecurityPolicy;
 import android.telephony.TelephonyManager;
 import android.text.TextUtils;
 import android.util.Base64;
+import android.util.SparseArray;
 import android.util.SparseLongArray;
 import android.view.Display;
 import android.view.SurfaceView;
@@ -516,6 +517,16 @@ public final class Util {
     return false;
   }
 
+  /**
+   * Tests whether a {@link SparseArray} contains a given {@code key}.
+   *
+   * <p>This implements {@code SparseArray#contains} for lower API versions.
+   */
+  @UnstableApi
+  public static <T> boolean containsKey(SparseArray<T> sparseArray, int key) {
+    return sparseArray.indexOfKey(key) >= 0;
+  }
+
   /**
    * Removes an indexed range from a List.
    *
diff --git a/libraries/effect/src/main/java/androidx/media3/effect/InputSwitcher.java b/libraries/effect/src/main/java/androidx/media3/effect/InputSwitcher.java
index 058492ed8d..8edab8770b 100644
--- a/libraries/effect/src/main/java/androidx/media3/effect/InputSwitcher.java
+++ b/libraries/effect/src/main/java/androidx/media3/effect/InputSwitcher.java
@@ -20,6 +20,7 @@ package androidx.media3.effect;
 import static androidx.media3.common.util.Assertions.checkNotNull;
 import static androidx.media3.common.util.Assertions.checkState;
 import static androidx.media3.common.util.Assertions.checkStateNotNull;
+import static androidx.media3.common.util.Util.containsKey;
 
 import android.content.Context;
 import android.util.SparseArray;
@@ -147,7 +148,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
    */
   public void switchToInput(@VideoFrameProcessor.InputType int newInputType) {
     checkStateNotNull(downstreamShaderProgram);
-    checkState(inputs.indexOfKey(newInputType) >= 0, "Input type not registered: " + newInputType);
+    checkState(containsKey(inputs, newInputType), "Input type not registered: " + newInputType);
 
     for (int i = 0; i < inputs.size(); i++) {
       @VideoFrameProcessor.InputType int inputType = inputs.keyAt(i);
diff --git a/libraries/transformer/src/main/java/androidx/media3/transformer/AudioMixerImpl.java b/libraries/transformer/src/main/java/androidx/media3/transformer/AudioMixerImpl.java
index 8a27712906..8bee6e9172 100644
--- a/libraries/transformer/src/main/java/androidx/media3/transformer/AudioMixerImpl.java
+++ b/libraries/transformer/src/main/java/androidx/media3/transformer/AudioMixerImpl.java
@@ -18,7 +18,7 @@ package androidx.media3.transformer;
 import static androidx.media3.common.audio.AudioProcessor.EMPTY_BUFFER;
 import static androidx.media3.common.util.Assertions.checkArgument;
 import static androidx.media3.common.util.Assertions.checkState;
-import static androidx.media3.common.util.Assertions.checkStateNotNull;
+import static androidx.media3.common.util.Util.containsKey;
 import static java.lang.Math.max;
 import static java.lang.Math.min;
 
@@ -153,7 +153,7 @@ import java.nio.ByteOrder;
 
   public boolean hasSource(int sourceId) {
     checkStateIsConfigured();
-    return sources.get(sourceId) != null;
+    return containsKey(sources, sourceId);
   }
 
   @Override
@@ -295,7 +295,8 @@ import java.nio.ByteOrder;
   }
 
   private SourceInfo getSourceById(int sourceId) {
-    return checkStateNotNull(sources.get(sourceId), "Source not found.");
+    checkState(containsKey(sources, sourceId), "Source not found.");
+    return sources.get(sourceId);
   }
 
   /** A buffer holding partially-mixed audio within an interval. */
diff --git a/libraries/transformer/src/main/java/androidx/media3/transformer/MuxerWrapper.java b/libraries/transformer/src/main/java/androidx/media3/transformer/MuxerWrapper.java
index ec3b2a18e3..8ebf121719 100644
--- a/libraries/transformer/src/main/java/androidx/media3/transformer/MuxerWrapper.java
+++ b/libraries/transformer/src/main/java/androidx/media3/transformer/MuxerWrapper.java
@@ -19,6 +19,7 @@ package androidx.media3.transformer;
 import static androidx.media3.common.util.Assertions.checkArgument;
 import static androidx.media3.common.util.Assertions.checkNotNull;
 import static androidx.media3.common.util.Assertions.checkState;
+import static androidx.media3.common.util.Util.containsKey;
 import static java.lang.Math.max;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 
@@ -174,9 +175,8 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
         trackType == C.TRACK_TYPE_AUDIO || trackType == C.TRACK_TYPE_VIDEO,
         "Unsupported track format: " + sampleMimeType);
 
-    // SparseArray.get() returns null by default if the value is not found.
     checkState(
-        trackTypeToInfo.get(trackType) == null, "There is already a track of type " + trackType);
+        !containsKey(trackTypeToInfo, trackType), "There is already a track of type " + trackType);
 
     ensureMuxerInitialized();
 
@@ -218,10 +218,8 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
   public boolean writeSample(
       @C.TrackType int trackType, ByteBuffer data, boolean isKeyFrame, long presentationTimeUs)
       throws Muxer.MuxerException {
-    @Nullable TrackInfo trackInfo = trackTypeToInfo.get(trackType);
-    // SparseArray.get() returns null by default if the value is not found.
-    checkArgument(
-        trackInfo != null, "Could not write sample because there is no track of type " + trackType);
+    checkArgument(containsKey(trackTypeToInfo, trackType));
+    TrackInfo trackInfo = trackTypeToInfo.get(trackType);
     boolean canWriteSample = canWriteSample(trackType, presentationTimeUs);
     if (trackType == C.TRACK_TYPE_VIDEO) {
       DebugTraceUtil.logEvent(
@@ -262,12 +260,11 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
    * @param trackType The {@link C.TrackType}.
    */
   public void endTrack(@C.TrackType int trackType) {
-    @Nullable TrackInfo trackInfo = trackTypeToInfo.get(trackType);
-    if (trackInfo == null) {
-      // SparseArray.get() returns null by default if the value is not found.
+    if (!containsKey(trackTypeToInfo, trackType)) {
       return;
     }
 
+    TrackInfo trackInfo = trackTypeToInfo.get(trackType);
     maxEndedTrackTimeUs = max(maxEndedTrackTimeUs, trackInfo.timeUs);
     listener.onTrackEnded(
         trackType, trackInfo.format, trackInfo.getAverageBitrate(), trackInfo.sampleCount);
diff --git a/libraries/transformer/src/main/java/androidx/media3/transformer/TransformerInternal.java b/libraries/transformer/src/main/java/androidx/media3/transformer/TransformerInternal.java
index 9dbf2b1233..696686a51a 100644
--- a/libraries/transformer/src/main/java/androidx/media3/transformer/TransformerInternal.java
+++ b/libraries/transformer/src/main/java/androidx/media3/transformer/TransformerInternal.java
@@ -18,6 +18,7 @@ package androidx.media3.transformer;
 
 import static androidx.media3.common.util.Assertions.checkArgument;
 import static androidx.media3.common.util.Assertions.checkState;
+import static androidx.media3.common.util.Util.containsKey;
 import static androidx.media3.transformer.AssetLoader.SUPPORTED_OUTPUT_TYPE_DECODED;
 import static androidx.media3.transformer.AssetLoader.SUPPORTED_OUTPUT_TYPE_ENCODED;
 import static androidx.media3.transformer.Composition.HDR_MODE_KEEP_HDR;
@@ -792,7 +793,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     public Format getAssetLoaderInputFormat(int sequenceIndex, @C.TrackType int trackType) {
       SparseArray<Format> trackTypeToFirstAssetLoaderInputFormat =
           sequencesMetadata.get(sequenceIndex).trackTypeToFirstAssetLoaderInputFormat;
-      checkState(contains(trackTypeToFirstAssetLoaderInputFormat, trackType));
+      checkState(containsKey(trackTypeToFirstAssetLoaderInputFormat, trackType));
       return trackTypeToFirstAssetLoaderInputFormat.get(trackType);
     }
 
@@ -833,7 +834,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
       @C.TrackType int trackType = getProcessedTrackType(assetLoaderInputFormat.sampleMimeType);
       SparseArray<Format> trackTypeToFirstAssetLoaderInputFormat =
           sequencesMetadata.get(sequenceIndex).trackTypeToFirstAssetLoaderInputFormat;
-      checkState(!contains(trackTypeToFirstAssetLoaderInputFormat, trackType));
+      checkState(!containsKey(trackTypeToFirstAssetLoaderInputFormat, trackType));
       trackTypeToFirstAssetLoaderInputFormat.put(trackType, assetLoaderInputFormat);
     }
 
@@ -841,7 +842,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
      * Returns the index of the primary sequence for a given {@link C.TrackType trackType}.
      *
      * <p>A primary sequence for a {@link C.TrackType trackType} is defined as the lowest indexed
-     * sequence that contains a track of the given {@code trackType}.
+     * sequence that containsKey a track of the given {@code trackType}.
      */
     public int getIndexForPrimarySequence(@C.TrackType int trackType) {
       checkState(
@@ -850,7 +851,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
       for (int i = 0; i < sequencesMetadata.size(); i++) {
         SparseArray<Format> trackTypeToFirstAssetLoaderInputFormat =
             sequencesMetadata.get(i).trackTypeToFirstAssetLoaderInputFormat;
-        if (contains(trackTypeToFirstAssetLoaderInputFormat, trackType)) {
+        if (containsKey(trackTypeToFirstAssetLoaderInputFormat, trackType)) {
           return i;
         }
       }
@@ -881,7 +882,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
      */
     public void registerGraphInput(@C.TrackType int trackType) {
       int numberOfGraphInputForTrackType = 1;
-      if (contains(trackTypeToNumberOfRegisteredGraphInput, trackType)) {
+      if (containsKey(trackTypeToNumberOfRegisteredGraphInput, trackType)) {
         numberOfGraphInputForTrackType += trackTypeToNumberOfRegisteredGraphInput.get(trackType);
       }
       trackTypeToNumberOfRegisteredGraphInput.put(trackType, numberOfGraphInputForTrackType);
@@ -894,7 +895,8 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     public boolean hasAssociatedAllTracksWithGraphInput(@C.TrackType int trackType) {
       int numberOfTracksForTrackType = 0;
       for (int i = 0; i < sequencesMetadata.size(); i++) {
-        if (contains(sequencesMetadata.get(i).trackTypeToFirstAssetLoaderInputFormat, trackType)) {
+        if (containsKey(
+            sequencesMetadata.get(i).trackTypeToFirstAssetLoaderInputFormat, trackType)) {
           numberOfTracksForTrackType++;
         }
       }
@@ -908,10 +910,10 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
       for (int i = 0; i < sequencesMetadata.size(); i++) {
         SparseArray<Format> trackTypeToFirstAssetLoaderInputFormat =
             sequencesMetadata.get(i).trackTypeToFirstAssetLoaderInputFormat;
-        if (contains(trackTypeToFirstAssetLoaderInputFormat, C.TRACK_TYPE_AUDIO)) {
+        if (containsKey(trackTypeToFirstAssetLoaderInputFormat, C.TRACK_TYPE_AUDIO)) {
           outputHasAudio = true;
         }
-        if (contains(trackTypeToFirstAssetLoaderInputFormat, C.TRACK_TYPE_VIDEO)) {
+        if (containsKey(trackTypeToFirstAssetLoaderInputFormat, C.TRACK_TYPE_VIDEO)) {
           outputHasVideo = true;
         }
       }
@@ -921,14 +923,14 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     /** Registers a {@link SampleExporter} for the given {@link C.TrackType trackType}. */
     public void registerSampleExporter(int trackType, SampleExporter sampleExporter) {
       checkState(
-          !contains(trackTypeToSampleExporter, trackType),
+          !containsKey(trackTypeToSampleExporter, trackType),
           "Exactly one SampleExporter can be added for each track type.");
       trackTypeToSampleExporter.put(trackType, sampleExporter);
     }
 
     /** Sets whether a track should be transcoded. */
     public void setShouldTranscode(@C.TrackType int trackType, boolean shouldTranscode) {
-      if (contains(trackTypeToShouldTranscode, trackType)) {
+      if (containsKey(trackTypeToShouldTranscode, trackType)) {
         checkState(shouldTranscode == trackTypeToShouldTranscode.get(trackType));
         return;
       }
@@ -937,7 +939,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
     /** Returns whether a track should be transcoded. */
     public boolean shouldTranscode(@C.TrackType int trackType) {
-      checkState(contains(trackTypeToShouldTranscode, trackType));
+      checkState(containsKey(trackTypeToShouldTranscode, trackType));
       return trackTypeToShouldTranscode.get(trackType);
     }
 
@@ -962,10 +964,5 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
         requiredTrackCount = C.LENGTH_UNSET;
       }
     }
-
-    /** Implements {@code SparseArray#contains} for lower API versions. */
-    private static <T> boolean contains(SparseArray<T> sparseArray, int key) {
-      return sparseArray.get(key) != null;
-    }
   }
 }