diff --git a/library/core/src/main/java/com/google/android/exoplayer2/offline/DefaultDownloadIndex.java b/library/core/src/main/java/com/google/android/exoplayer2/offline/DefaultDownloadIndex.java
index 2a62b0602c..3388424e6e 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/offline/DefaultDownloadIndex.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/offline/DefaultDownloadIndex.java
@@ -15,12 +15,15 @@
  */
 package com.google.android.exoplayer2.offline;
 
+import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
+
 import android.content.ContentValues;
 import android.database.Cursor;
 import android.database.SQLException;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteException;
 import android.net.Uri;
+import android.text.TextUtils;
 import androidx.annotation.GuardedBy;
 import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
@@ -371,7 +374,7 @@ public final class DefaultDownloadIndex implements WritableDownloadIndex {
   }
 
   /** Infers the MIME type from a v2 table row. */
-  private static String inferMimeType(String downloadType) {
+  private static String inferMimeType(@Nullable String downloadType) {
     if ("dash".equals(downloadType)) {
       return MimeTypes.APPLICATION_MPD;
     } else if ("hls".equals(downloadType)) {
@@ -441,8 +444,8 @@ public final class DefaultDownloadIndex implements WritableDownloadIndex {
     byte[] keySetId = cursor.getBlob(COLUMN_INDEX_KEY_SET_ID);
     DownloadRequest request =
         new DownloadRequest.Builder(
-                /* id= */ cursor.getString(COLUMN_INDEX_ID),
-                /* uri= */ Uri.parse(cursor.getString(COLUMN_INDEX_URI)))
+                /* id= */ checkNotNull(cursor.getString(COLUMN_INDEX_ID)),
+                /* uri= */ Uri.parse(checkNotNull(cursor.getString(COLUMN_INDEX_URI))))
             .setMimeType(cursor.getString(COLUMN_INDEX_MIME_TYPE))
             .setStreamKeys(decodeStreamKeys(cursor.getString(COLUMN_INDEX_STREAM_KEYS)))
             .setKeySetId(keySetId.length > 0 ? keySetId : null)
@@ -493,7 +496,8 @@ public final class DefaultDownloadIndex implements WritableDownloadIndex {
      */
     DownloadRequest request =
         new DownloadRequest.Builder(
-                /* id= */ cursor.getString(0), /* uri= */ Uri.parse(cursor.getString(2)))
+                /* id= */ checkNotNull(cursor.getString(0)),
+                /* uri= */ Uri.parse(checkNotNull(cursor.getString(2))))
             .setMimeType(inferMimeType(cursor.getString(1)))
             .setStreamKeys(decodeStreamKeys(cursor.getString(3)))
             .setCustomCacheKey(cursor.getString(4))
@@ -519,9 +523,9 @@ public final class DefaultDownloadIndex implements WritableDownloadIndex {
         downloadProgress);
   }
 
-  private static List<StreamKey> decodeStreamKeys(String encodedStreamKeys) {
+  private static List<StreamKey> decodeStreamKeys(@Nullable String encodedStreamKeys) {
     ArrayList<StreamKey> streamKeys = new ArrayList<>();
-    if (encodedStreamKeys.isEmpty()) {
+    if (TextUtils.isEmpty(encodedStreamKeys)) {
       return streamKeys;
     }
     String[] streamKeysStrings = Util.split(encodedStreamKeys, ",");
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CacheFileMetadataIndex.java b/library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CacheFileMetadataIndex.java
index e288a5258e..ec0ff46ac2 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CacheFileMetadataIndex.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CacheFileMetadataIndex.java
@@ -15,6 +15,8 @@
  */
 package com.google.android.exoplayer2.upstream.cache;
 
+import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
+
 import android.content.ContentValues;
 import android.database.Cursor;
 import android.database.SQLException;
@@ -146,7 +148,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     try (Cursor cursor = getCursor()) {
       Map<String, CacheFileMetadata> fileMetadata = new HashMap<>(cursor.getCount());
       while (cursor.moveToNext()) {
-        String name = cursor.getString(COLUMN_INDEX_NAME);
+        String name = checkNotNull(cursor.getString(COLUMN_INDEX_NAME));
         long length = cursor.getLong(COLUMN_INDEX_LENGTH);
         long lastTouchTimestamp = cursor.getLong(COLUMN_INDEX_LAST_TOUCH_TIMESTAMP);
         fileMetadata.put(name, new CacheFileMetadata(length, lastTouchTimestamp));
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CachedContentIndex.java b/library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CachedContentIndex.java
index ce69d5a46c..f8289809f8 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CachedContentIndex.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CachedContentIndex.java
@@ -832,7 +832,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
         try (Cursor cursor = getCursor()) {
           while (cursor.moveToNext()) {
             int id = cursor.getInt(COLUMN_INDEX_ID);
-            String key = cursor.getString(COLUMN_INDEX_KEY);
+            String key = checkNotNull(cursor.getString(COLUMN_INDEX_KEY));
             byte[] metadataBytes = cursor.getBlob(COLUMN_INDEX_METADATA);
 
             ByteArrayInputStream inputStream = new ByteArrayInputStream(metadataBytes);