diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/BinarySearchSeeker.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/BinarySearchSeeker.java
index 9d5f7f1788..c4375e490c 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/BinarySearchSeeker.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/BinarySearchSeeker.java
@@ -174,7 +174,8 @@ public abstract class BinarySearchSeeker {
   public int handlePendingSeek(ExtractorInput input, PositionHolder seekPositionHolder)
       throws InterruptedException, IOException {
     while (true) {
-      SeekOperationParams seekOperationParams = Assertions.checkNotNull(this.seekOperationParams);
+      SeekOperationParams seekOperationParams =
+          Assertions.checkStateNotNull(this.seekOperationParams);
       long floorPosition = seekOperationParams.getFloorBytePosition();
       long ceilingPosition = seekOperationParams.getCeilingBytePosition();
       long searchPosition = seekOperationParams.getNextSearchBytePosition();
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/FlacSeekTableSeekMap.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/FlacSeekTableSeekMap.java
index a711f09e2f..be65e77c95 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/FlacSeekTableSeekMap.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/FlacSeekTableSeekMap.java
@@ -52,7 +52,7 @@ public final class FlacSeekTableSeekMap implements SeekMap {
 
   @Override
   public SeekPoints getSeekPoints(long timeUs) {
-    Assertions.checkNotNull(flacStreamMetadata.seekTable);
+    Assertions.checkStateNotNull(flacStreamMetadata.seekTable);
     long[] pointSampleNumbers = flacStreamMetadata.seekTable.pointSampleNumbers;
     long[] pointOffsets = flacStreamMetadata.seekTable.pointOffsets;
 
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java
index 5e6164249b..5aed97ec9a 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java
@@ -80,7 +80,7 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
 
   @Override
   public boolean read(ExtractorInput input) throws IOException, InterruptedException {
-    Assertions.checkNotNull(processor);
+    Assertions.checkStateNotNull(processor);
     while (true) {
       MasterElement head = masterElementsStack.peek();
       if (head != null && input.getPosition() >= head.elementEndPosition) {
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp3/XingSeeker.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp3/XingSeeker.java
index aa1d8be316..816b647675 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp3/XingSeeker.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp3/XingSeeker.java
@@ -133,7 +133,7 @@ import com.google.android.exoplayer2.util.Util;
       scaledPosition = 256;
     } else {
       int prevTableIndex = (int) percent;
-      long[] tableOfContents = Assertions.checkNotNull(this.tableOfContents);
+      long[] tableOfContents = Assertions.checkStateNotNull(this.tableOfContents);
       double prevScaledPosition = tableOfContents[prevTableIndex];
       double nextScaledPosition = prevTableIndex == 99 ? 256 : tableOfContents[prevTableIndex + 1];
       // Linearly interpolate between the two scaled positions.
@@ -153,7 +153,7 @@ import com.google.android.exoplayer2.util.Util;
     if (!isSeekable() || positionOffset <= xingFrameSize) {
       return 0L;
     }
-    long[] tableOfContents = Assertions.checkNotNull(this.tableOfContents);
+    long[] tableOfContents = Assertions.checkStateNotNull(this.tableOfContents);
     double scaledPosition = (positionOffset * 256d) / dataSize;
     int prevTableIndex = Util.binarySearchFloor(tableOfContents, (long) scaledPosition, true, true);
     long prevTimeUs = getTimeUsForTableIndex(prevTableIndex);
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ogg/StreamReader.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ogg/StreamReader.java
index 41ae394de2..ed0e3637da 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ogg/StreamReader.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ogg/StreamReader.java
@@ -177,7 +177,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     }
 
     if (!seekMapSet) {
-      SeekMap seekMap = Assertions.checkNotNull(oggSeeker.createSeekMap());
+      SeekMap seekMap = Assertions.checkStateNotNull(oggSeeker.createSeekMap());
       extractorOutput.seekMap(seekMap);
       seekMapSet = true;
     }
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/AdtsExtractor.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/AdtsExtractor.java
index 86dacd8c30..d14b6a0b3e 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/AdtsExtractor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/AdtsExtractor.java
@@ -20,7 +20,6 @@ import static com.google.android.exoplayer2.metadata.id3.Id3Decoder.ID3_HEADER_L
 import static com.google.android.exoplayer2.metadata.id3.Id3Decoder.ID3_TAG;
 
 import androidx.annotation.IntDef;
-import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.ParserException;
 import com.google.android.exoplayer2.extractor.ConstantBitrateSeekMap;
@@ -39,6 +38,8 @@ import java.io.IOException;
 import java.lang.annotation.Documented;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+import org.checkerframework.checker.nullness.qual.RequiresNonNull;
 
 /**
  * Extracts data from AAC bit streams with ADTS framing.
@@ -86,7 +87,7 @@ public final class AdtsExtractor implements Extractor {
   private final ParsableByteArray scratch;
   private final ParsableBitArray scratchBits;
 
-  @Nullable private ExtractorOutput extractorOutput;
+  @MonotonicNonNull private ExtractorOutput extractorOutput;
 
   private long firstSampleTimestampUs;
   private long firstFramePosition;
@@ -180,6 +181,8 @@ public final class AdtsExtractor implements Extractor {
   @Override
   public int read(ExtractorInput input, PositionHolder seekPosition)
       throws IOException, InterruptedException {
+    Assertions.checkStateNotNull(extractorOutput); // Asserts that init has been called.
+
     long inputLength = input.getLength();
     boolean canUseConstantBitrateSeeking =
         (flags & FLAG_ENABLE_CONSTANT_BITRATE_SEEKING) != 0 && inputLength != C.LENGTH_UNSET;
@@ -230,6 +233,7 @@ public final class AdtsExtractor implements Extractor {
     return firstFramePosition;
   }
 
+  @RequiresNonNull("extractorOutput")
   private void maybeOutputSeekMap(
       long inputLength, boolean canUseConstantBitrateSeeking, boolean readEndOfStream) {
     if (hasOutputSeekMap) {
@@ -244,7 +248,6 @@ public final class AdtsExtractor implements Extractor {
       return;
     }
 
-    ExtractorOutput extractorOutput = Assertions.checkNotNull(this.extractorOutput);
     if (useConstantBitrateSeeking && reader.getSampleDurationUs() != C.TIME_UNSET) {
       extractorOutput.seekMap(getConstantBitrateSeekMap(inputLength));
     } else {