Remove most nullness marking from Transformer demos

The nullness checking is very verbose and redundant in some places, for
example, the ensures-non-null marking in the transformer activity, and it makes
changing features in the demo app more time consuming. The cost/benefit balance
seems to be in favor of removing this for demo code.

Note: the ExoPlayer main demo has nullness checks turned off.
PiperOrigin-RevId: 641890618

demos/composition/src/main/java/androidx/media3/demo/composition/CompositionPreviewActivity.java

@@ -15,10 +15,6 @@
  */
 package androidx.media3.demo.composition;
 
-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 android.app.Activity;
 import android.content.DialogInterface;
 import android.os.Bundle;
@@ -59,7 +55,6 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
-import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.json.JSONException;
 import org.json.JSONObject;
 
@@ -70,18 +65,17 @@ import org.json.JSONObject;
 public final class CompositionPreviewActivity extends AppCompatActivity {
   private static final String TAG = "CompPreviewActivity";
 
-  private final ArrayList<String> sequenceAssetTitles = new ArrayList<>();
+  private ArrayList<String> sequenceAssetTitles;
-
+  private boolean[] selectedMediaItems;
-  @Nullable private boolean[] selectedMediaItems = null;
+  private String[] presetDescriptions;
-  private String[] presetDescriptions = new String[0];
+  private AssetItemAdapter assetItemAdapter;
-  @Nullable private AssetItemAdapter assetItemAdapter;
   @Nullable private CompositionPlayer compositionPlayer;
   @Nullable private Transformer transformer;
   @Nullable private File outputFile;
-  private @MonotonicNonNull PlayerView playerView;
+  private PlayerView playerView;
-  private @MonotonicNonNull AppCompatButton exportButton;
+  private AppCompatButton exportButton;
-  private @MonotonicNonNull AppCompatTextView exportInformationTextView;
+  private AppCompatTextView exportInformationTextView;
-  private @MonotonicNonNull Stopwatch exportStopwatch;
+  private Stopwatch exportStopwatch;
 
   @Override
   protected void onCreate(@Nullable Bundle savedInstanceState) {
@@ -106,8 +100,9 @@ public final class CompositionPreviewActivity extends AppCompatActivity {
     selectedMediaItems = new boolean[presetDescriptions.length];
     selectedMediaItems[0] = true;
     selectedMediaItems[2] = true;
-    for (int i = 0; i < checkNotNull(selectedMediaItems).length; i++) {
+    sequenceAssetTitles = new ArrayList<>();
-      if (checkNotNull(selectedMediaItems)[i]) {
+    for (int i = 0; i < selectedMediaItems.length; i++) {
+      if (selectedMediaItems[i]) {
         sequenceAssetTitles.add(presetDescriptions[i]);
       }
     }
@@ -127,38 +122,27 @@ public final class CompositionPreviewActivity extends AppCompatActivity {
   @Override
   protected void onStart() {
     super.onStart();
-    checkStateNotNull(playerView).onResume();
+    playerView.onResume();
   }
 
   @Override
   protected void onStop() {
     super.onStop();
-    checkStateNotNull(playerView).onPause();
+    playerView.onPause();
     releasePlayer();
     cancelExport();
-    checkStateNotNull(exportStopwatch).reset();
+    exportStopwatch.reset();
   }
 
   private Composition prepareComposition() {
-    // Reading from resources here does not create a performance bottleneck, this
-    // method is called as part of more expensive operations.
     String[] presetUris = getResources().getStringArray(/* id= */ R.array.preset_uris);
-    checkState(
-        /* expression= */ checkStateNotNull(presetUris).length == presetDescriptions.length,
-        /* errorMessage= */ "Unexpected array length "
-            + getResources().getResourceName(R.array.preset_uris));
     int[] presetDurationsUs = getResources().getIntArray(/* id= */ R.array.preset_durations);
-    checkState(
-        /* expression= */ checkStateNotNull(presetDurationsUs).length == presetDescriptions.length,
-        /* errorMessage= */ "Unexpected array length "
-            + getResources().getResourceName(R.array.preset_durations));
-
     List<EditedMediaItem> mediaItems = new ArrayList<>();
     ImmutableList<Effect> effects =
         ImmutableList.of(
             MatrixTransformationFactory.createDizzyCropEffect(), RgbFilter.createGrayscaleFilter());
-    for (int i = 0; i < checkNotNull(selectedMediaItems).length; i++) {
+    for (int i = 0; i < selectedMediaItems.length; i++) {
-      if (checkNotNull(selectedMediaItems)[i]) {
+      if (selectedMediaItems[i]) {
         SonicAudioProcessor pitchChanger = new SonicAudioProcessor();
         pitchChanger.setPitch(mediaItems.size() % 2 == 0 ? 2f : 0.2f);
         MediaItem mediaItem =
@@ -190,12 +174,12 @@ public final class CompositionPreviewActivity extends AppCompatActivity {
   private void previewComposition(View view) {
     releasePlayer();
     Composition composition = prepareComposition();
-    checkStateNotNull(playerView).setPlayer(null);
+    playerView.setPlayer(null);
 
     CompositionPlayer player = new CompositionPlayer.Builder(getApplicationContext()).build();
     this.compositionPlayer = player;
-    checkStateNotNull(playerView).setPlayer(compositionPlayer);
+    playerView.setPlayer(compositionPlayer);
-    checkStateNotNull(playerView).setControllerAutoShow(false);
+    playerView.setControllerAutoShow(false);
     player.addListener(
         new Player.Listener() {
           @Override
@@ -213,8 +197,7 @@ public final class CompositionPreviewActivity extends AppCompatActivity {
   private void selectPreset(View view) {
     new AlertDialog.Builder(/* context= */ this)
         .setTitle(R.string.select_preset_title)
-        .setMultiChoiceItems(
+        .setMultiChoiceItems(presetDescriptions, selectedMediaItems, this::selectPresetInDialog)
-            presetDescriptions, checkNotNull(selectedMediaItems), this::selectPresetInDialog)
         .setPositiveButton(android.R.string.ok, /* listener= */ null)
         .setCancelable(false)
         .create()
@@ -222,18 +205,15 @@ public final class CompositionPreviewActivity extends AppCompatActivity {
   }
 
   private void selectPresetInDialog(DialogInterface dialog, int which, boolean isChecked) {
-    if (selectedMediaItems == null) {
-      return;
-    }
     selectedMediaItems[which] = isChecked;
     // The items will be added to a the sequence in the order they were selected.
     if (isChecked) {
       sequenceAssetTitles.add(presetDescriptions[which]);
-      checkNotNull(assetItemAdapter).notifyItemInserted(sequenceAssetTitles.size() - 1);
+      assetItemAdapter.notifyItemInserted(sequenceAssetTitles.size() - 1);
     } else {
       int index = sequenceAssetTitles.indexOf(presetDescriptions[which]);
       sequenceAssetTitles.remove(presetDescriptions[which]);
-      checkNotNull(assetItemAdapter).notifyItemRemoved(index);
+      assetItemAdapter.notifyItemRemoved(index);
     }
   }
 
@@ -253,23 +233,23 @@ public final class CompositionPreviewActivity extends AppCompatActivity {
               "Aborting export! Unable to create output file: " + e,
               Toast.LENGTH_LONG)
           .show();
-      Log.e(TAG, "Aborting export! Unable to create output file: " + e);
+      Log.e(TAG, "Aborting export! Unable to create output file: ", e);
       return;
     }
     String filePath = outputFile.getAbsolutePath();
 
     transformer =
-        new Transformer.Builder(this)
+        new Transformer.Builder(/* context= */ this)
             .addListener(
                 new Transformer.Listener() {
                   @Override
                   public void onCompleted(Composition composition, ExportResult exportResult) {
-                    checkStateNotNull(exportStopwatch).stop();
+                    exportStopwatch.stop();
                     long elapsedTimeMs = exportStopwatch.elapsed(TimeUnit.MILLISECONDS);
                     String details =
                         getString(R.string.export_completed, elapsedTimeMs / 1000.f, filePath);
                     Log.i(TAG, details);
-                    checkStateNotNull(exportInformationTextView).setText(details);
+                    exportInformationTextView.setText(details);
 
                     try {
                       JSONObject resultJson =
@@ -289,22 +269,22 @@ public final class CompositionPreviewActivity extends AppCompatActivity {
                       Composition composition,
                       ExportResult exportResult,
                       ExportException exportException) {
-                    checkStateNotNull(exportStopwatch).stop();
+                    exportStopwatch.stop();
                     Toast.makeText(
                             getApplicationContext(),
                             "Export error: " + exportException,
                             Toast.LENGTH_LONG)
                         .show();
                     Log.e(TAG, "Export error", exportException);
-                    checkStateNotNull(exportInformationTextView).setText(R.string.export_error);
+                    exportInformationTextView.setText(R.string.export_error);
                   }
                 })
             .build();
 
-    checkStateNotNull(exportInformationTextView).setText(R.string.export_started);
+    exportInformationTextView.setText(R.string.export_started);
-    checkStateNotNull(exportStopwatch).reset();
+    exportStopwatch.reset();
     exportStopwatch.start();
-    checkStateNotNull(transformer).start(composition, filePath);
+    transformer.start(composition, filePath);
     Log.i(TAG, "Export started");
   }
 
@@ -325,7 +305,7 @@ public final class CompositionPreviewActivity extends AppCompatActivity {
       outputFile.delete();
       outputFile = null;
     }
-    checkStateNotNull(exportInformationTextView).setText("");
+    exportInformationTextView.setText("");
   }
 
   /**

demos/transformer/src/main/java/androidx/media3/demo/transformer/ConfigurationActivity.java

@@ -17,7 +17,6 @@ package androidx.media3.demo.transformer;
 
 import static android.Manifest.permission.READ_EXTERNAL_STORAGE;
 import static android.Manifest.permission.READ_MEDIA_VIDEO;
-import static androidx.media3.common.util.Assertions.checkNotNull;
 import static androidx.media3.common.util.Assertions.checkState;
 import static androidx.media3.common.util.Util.SDK_INT;
 import static androidx.media3.transformer.Composition.HDR_MODE_EXPERIMENTAL_FORCE_INTERPRET_HDR_AS_SDR;
@@ -56,8 +55,6 @@ import com.google.android.material.slider.Slider;
 import com.google.common.collect.ImmutableMap;
 import java.util.Arrays;
 import java.util.List;
-import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
-import org.checkerframework.checker.nullness.qual.RequiresNonNull;
 
 /**
  * An {@link Activity} that sets the configuration to use for exporting and playing media, using
@@ -154,35 +151,35 @@ public final class ConfigurationActivity extends AppCompatActivity {
   private static final String SAME_AS_INPUT_OPTION = "same as input";
   private static final float HALF_DIAGONAL = 1f / (float) Math.sqrt(2);
 
-  private @MonotonicNonNull Runnable onPermissionsGranted;
+  private Runnable onPermissionsGranted;
-  private @MonotonicNonNull ActivityResultLauncher<Intent> videoLocalFilePickerLauncher;
+  private ActivityResultLauncher<Intent> videoLocalFilePickerLauncher;
-  private @MonotonicNonNull ActivityResultLauncher<Intent> overlayLocalFilePickerLauncher;
+  private ActivityResultLauncher<Intent> overlayLocalFilePickerLauncher;
-  private @MonotonicNonNull Button selectPresetFileButton;
+  private Button selectPresetFileButton;
-  private @MonotonicNonNull Button selectLocalFileButton;
+  private Button selectLocalFileButton;
-  private @MonotonicNonNull TextView selectedFileTextView;
+  private TextView selectedFileTextView;
-  private @MonotonicNonNull CheckBox removeAudioCheckbox;
+  private CheckBox removeAudioCheckbox;
-  private @MonotonicNonNull CheckBox removeVideoCheckbox;
+  private CheckBox removeVideoCheckbox;
-  private @MonotonicNonNull CheckBox flattenForSlowMotionCheckbox;
+  private CheckBox flattenForSlowMotionCheckbox;
-  private @MonotonicNonNull CheckBox forceAudioTrackCheckbox;
+  private CheckBox forceAudioTrackCheckbox;
-  private @MonotonicNonNull Spinner audioMimeSpinner;
+  private Spinner audioMimeSpinner;
-  private @MonotonicNonNull Spinner videoMimeSpinner;
+  private Spinner videoMimeSpinner;
-  private @MonotonicNonNull Spinner resolutionHeightSpinner;
+  private Spinner resolutionHeightSpinner;
-  private @MonotonicNonNull Spinner scaleSpinner;
+  private Spinner scaleSpinner;
-  private @MonotonicNonNull Spinner rotateSpinner;
+  private Spinner rotateSpinner;
-  private @MonotonicNonNull CheckBox trimCheckBox;
+  private CheckBox trimCheckBox;
-  private @MonotonicNonNull CheckBox enableFallbackCheckBox;
+  private CheckBox enableFallbackCheckBox;
-  private @MonotonicNonNull CheckBox enableAnalyzerModeCheckBox;
+  private CheckBox enableAnalyzerModeCheckBox;
-  private @MonotonicNonNull CheckBox enableDebugPreviewCheckBox;
+  private CheckBox enableDebugPreviewCheckBox;
-  private @MonotonicNonNull CheckBox enableDebugTracingCheckBox;
+  private CheckBox enableDebugTracingCheckBox;
-  private @MonotonicNonNull CheckBox abortSlowExportCheckBox;
+  private CheckBox abortSlowExportCheckBox;
-  private @MonotonicNonNull CheckBox produceFragmentedMp4CheckBox;
+  private CheckBox produceFragmentedMp4CheckBox;
-  private @MonotonicNonNull Spinner hdrModeSpinner;
+  private Spinner hdrModeSpinner;
-  private @MonotonicNonNull Button selectAudioEffectsButton;
+  private Button selectAudioEffectsButton;
-  private @MonotonicNonNull Button selectVideoEffectsButton;
+  private Button selectVideoEffectsButton;
-  private boolean @MonotonicNonNull [] audioEffectsSelections;
+  private boolean[] audioEffectsSelections;
-  private boolean @MonotonicNonNull [] videoEffectsSelections;
+  private boolean[] videoEffectsSelections;
-  private String[] presetFileDescriptions = new String[0];
+  private String[] presetFileDescriptions;
-  private @Nullable Uri localFileUri;
+  private Uri localFileUri;
   private int inputUriPosition;
   private long trimStartMs;
   private long trimEndMs;
@@ -198,9 +195,9 @@ public final class ConfigurationActivity extends AppCompatActivity {
   private float periodicVignetteCenterY;
   private float periodicVignetteInnerRadius;
   private float periodicVignetteOuterRadius;
-  private @MonotonicNonNull String bitmapOverlayUri;
+  private String bitmapOverlayUri;
   private float bitmapOverlayAlpha;
-  private @MonotonicNonNull String textOverlayText;
+  private String textOverlayText;
   private int textOverlayTextColor;
   private float textOverlayAlpha;
 
@@ -227,7 +224,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
     selectLocalFileButton.setOnClickListener(
         view ->
             selectLocalFile(
-                checkNotNull(videoLocalFilePickerLauncher),
+                videoLocalFilePickerLauncher,
                 /* mimeTypes= */ new String[] {"image/*", "video/*", "audio/*"}));
 
     selectedFileTextView = findViewById(R.id.selected_file_text_view);
@@ -331,7 +328,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
     if (requestCode == FILE_PERMISSION_REQUEST_CODE
         && grantResults.length == 1
         && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
-      checkNotNull(onPermissionsGranted).run();
+      onPermissionsGranted.run();
     } else {
       Toast.makeText(
               getApplicationContext(), getString(R.string.permission_denied), Toast.LENGTH_LONG)
@@ -344,9 +341,9 @@ public final class ConfigurationActivity extends AppCompatActivity {
     super.onResume();
     @Nullable Uri intentUri = getIntent().getData();
     if (intentUri != null) {
-      checkNotNull(selectPresetFileButton).setEnabled(false);
+      selectPresetFileButton.setEnabled(false);
-      checkNotNull(selectLocalFileButton).setEnabled(false);
+      selectLocalFileButton.setEnabled(false);
-      checkNotNull(selectedFileTextView).setText(intentUri.toString());
+      selectedFileTextView.setText(intentUri.toString());
     }
   }
 
@@ -356,26 +353,6 @@ public final class ConfigurationActivity extends AppCompatActivity {
     setIntent(intent);
   }
 
-  @RequiresNonNull({
-    "removeAudioCheckbox",
-    "removeVideoCheckbox",
-    "flattenForSlowMotionCheckbox",
-    "forceAudioTrackCheckbox",
-    "audioMimeSpinner",
-    "videoMimeSpinner",
-    "resolutionHeightSpinner",
-    "scaleSpinner",
-    "rotateSpinner",
-    "trimCheckBox",
-    "enableFallbackCheckBox",
-    "enableAnalyzerModeCheckBox",
-    "enableDebugPreviewCheckBox",
-    "abortSlowExportCheckBox",
-    "produceFragmentedMp4CheckBox",
-    "hdrModeSpinner",
-    "audioEffectsSelections",
-    "videoEffectsSelections"
-  })
   private void startExport(View view) {
     Intent transformerIntent = new Intent(/* packageContext= */ this, TransformerActivity.class);
     Bundle bundle = new Bundle();
@@ -415,8 +392,8 @@ public final class ConfigurationActivity extends AppCompatActivity {
     bundle.putBoolean(ENABLE_DEBUG_PREVIEW, enableDebugPreviewCheckBox.isChecked());
     bundle.putBoolean(ABORT_SLOW_EXPORT, abortSlowExportCheckBox.isChecked());
     bundle.putBoolean(PRODUCE_FRAGMENTED_MP4, produceFragmentedMp4CheckBox.isChecked());
-    String selectedhdrMode = String.valueOf(hdrModeSpinner.getSelectedItem());
+    String selectedHdrMode = String.valueOf(hdrModeSpinner.getSelectedItem());
-    bundle.putInt(HDR_MODE, checkNotNull(HDR_MODE_DESCRIPTIONS.get(selectedhdrMode)));
+    bundle.putInt(HDR_MODE, HDR_MODE_DESCRIPTIONS.get(selectedHdrMode));
     bundle.putBooleanArray(AUDIO_EFFECTS_SELECTIONS, audioEffectsSelections);
     bundle.putBooleanArray(VIDEO_EFFECTS_SELECTIONS, videoEffectsSelections);
     bundle.putInt(COLOR_FILTER_SELECTION, colorFilterSelection);
@@ -462,7 +439,6 @@ public final class ConfigurationActivity extends AppCompatActivity {
         .show();
   }
 
-  @RequiresNonNull("selectedFileTextView")
   private void selectPresetFileInDialog(DialogInterface dialog, int which) {
     inputUriPosition = which;
     localFileUri = null;
@@ -487,14 +463,13 @@ public final class ConfigurationActivity extends AppCompatActivity {
     Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
     intent.setType("*/*");
     intent.putExtra(Intent.EXTRA_MIME_TYPES, mimeTypes);
-    checkNotNull(localFilePickerLauncher).launch(intent);
+    localFilePickerLauncher.launch(intent);
   }
 
-  @RequiresNonNull("selectedFileTextView")
   private void videoLocalFilePickerLauncherResult(ActivityResult result) {
     Intent data = result.getData();
     if (data != null) {
-      localFileUri = checkNotNull(data.getData());
+      localFileUri = data.getData();
       selectedFileTextView.setText(localFileUri.toString());
     } else {
       Toast.makeText(
@@ -508,7 +483,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
   private void overlayLocalFilePickerLauncherResult(ActivityResult result) {
     Intent data = result.getData();
     if (data != null) {
-      bitmapOverlayUri = checkNotNull(data.getData()).toString();
+      bitmapOverlayUri = data.getData().toString();
     } else {
       Toast.makeText(
               getApplicationContext(),
@@ -521,8 +496,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
   private void selectAudioEffects(View view, String[] audioEffectsNames) {
     new AlertDialog.Builder(/* context= */ this)
         .setTitle(R.string.select_audio_effects)
-        .setMultiChoiceItems(
+        .setMultiChoiceItems(audioEffectsNames, audioEffectsSelections, this::selectAudioEffect)
-            audioEffectsNames, checkNotNull(audioEffectsSelections), this::selectAudioEffect)
         .setPositiveButton(android.R.string.ok, /* listener= */ null)
         .create()
         .show();
@@ -531,8 +505,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
   private void selectVideoEffects(View view, String[] videoEffectsNames) {
     new AlertDialog.Builder(/* context= */ this)
         .setTitle(R.string.select_video_effects)
-        .setMultiChoiceItems(
+        .setMultiChoiceItems(videoEffectsNames, videoEffectsSelections, this::selectVideoEffect)
-            videoEffectsNames, checkNotNull(videoEffectsSelections), this::selectVideoEffect)
         .setPositiveButton(android.R.string.ok, /* listener= */ null)
         .create()
         .show();
@@ -543,8 +516,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
       return;
     }
     View dialogView = getLayoutInflater().inflate(R.layout.trim_options, /* root= */ null);
-    RangeSlider trimRangeSlider =
+    RangeSlider trimRangeSlider = dialogView.findViewById(R.id.trim_bounds_range_slider);
-        checkNotNull(dialogView.findViewById(R.id.trim_bounds_range_slider));
     trimRangeSlider.setValues(0f, 1f); // seconds
     new AlertDialog.Builder(/* context= */ this)
         .setView(dialogView)
@@ -559,12 +531,10 @@ public final class ConfigurationActivity extends AppCompatActivity {
         .show();
   }
 
-  @RequiresNonNull("audioEffectsSelections")
   private void selectAudioEffect(DialogInterface dialog, int which, boolean isChecked) {
     audioEffectsSelections[which] = isChecked;
   }
 
-  @RequiresNonNull("videoEffectsSelections")
   private void selectVideoEffect(DialogInterface dialog, int which, boolean isChecked) {
     videoEffectsSelections[which] = isChecked;
     if (!isChecked) {
@@ -617,10 +587,9 @@ public final class ConfigurationActivity extends AppCompatActivity {
   private void controlRgbAdjustmentsScale() {
     View dialogView =
         getLayoutInflater().inflate(R.layout.rgb_adjustment_options, /* root= */ null);
-    Slider redScaleSlider = checkNotNull(dialogView.findViewById(R.id.rgb_adjustment_red_scale));
+    Slider redScaleSlider = dialogView.findViewById(R.id.rgb_adjustment_red_scale);
-    Slider greenScaleSlider =
+    Slider greenScaleSlider = dialogView.findViewById(R.id.rgb_adjustment_green_scale);
-        checkNotNull(dialogView.findViewById(R.id.rgb_adjustment_green_scale));
+    Slider blueScaleSlider = dialogView.findViewById(R.id.rgb_adjustment_blue_scale);
-    Slider blueScaleSlider = checkNotNull(dialogView.findViewById(R.id.rgb_adjustment_blue_scale));
     new AlertDialog.Builder(/* context= */ this)
         .setTitle(R.string.rgb_adjustment_options)
         .setView(dialogView)
@@ -637,7 +606,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
 
   private void controlContrastSettings() {
     View dialogView = getLayoutInflater().inflate(R.layout.contrast_options, /* root= */ null);
-    Slider contrastSlider = checkNotNull(dialogView.findViewById(R.id.contrast_slider));
+    Slider contrastSlider = dialogView.findViewById(R.id.contrast_slider);
     new AlertDialog.Builder(/* context= */ this)
         .setView(dialogView)
         .setPositiveButton(
@@ -650,11 +619,9 @@ public final class ConfigurationActivity extends AppCompatActivity {
   private void controlHslAdjustmentSettings() {
     View dialogView =
         getLayoutInflater().inflate(R.layout.hsl_adjustment_options, /* root= */ null);
-    Slider hueAdjustmentSlider = checkNotNull(dialogView.findViewById(R.id.hsl_adjustments_hue));
+    Slider hueAdjustmentSlider = dialogView.findViewById(R.id.hsl_adjustments_hue);
-    Slider saturationAdjustmentSlider =
+    Slider saturationAdjustmentSlider = dialogView.findViewById(R.id.hsl_adjustments_saturation);
-        checkNotNull(dialogView.findViewById(R.id.hsl_adjustments_saturation));
+    Slider lightnessAdjustmentSlider = dialogView.findViewById(R.id.hsl_adjustment_lightness);
-    Slider lightnessAdjustmentSlider =
-        checkNotNull(dialogView.findViewById(R.id.hsl_adjustment_lightness));
     new AlertDialog.Builder(/* context= */ this)
         .setTitle(R.string.hsl_adjustment_options)
         .setView(dialogView)
@@ -672,12 +639,10 @@ public final class ConfigurationActivity extends AppCompatActivity {
   private void controlPeriodicVignetteSettings() {
     View dialogView =
         getLayoutInflater().inflate(R.layout.periodic_vignette_options, /* root= */ null);
-    Slider centerXSlider =
+    Slider centerXSlider = dialogView.findViewById(R.id.periodic_vignette_center_x_slider);
-        checkNotNull(dialogView.findViewById(R.id.periodic_vignette_center_x_slider));
+    Slider centerYSlider = dialogView.findViewById(R.id.periodic_vignette_center_y_slider);
-    Slider centerYSlider =
-        checkNotNull(dialogView.findViewById(R.id.periodic_vignette_center_y_slider));
     RangeSlider radiusRangeSlider =
-        checkNotNull(dialogView.findViewById(R.id.periodic_vignette_radius_range_slider));
+        dialogView.findViewById(R.id.periodic_vignette_radius_range_slider);
     radiusRangeSlider.setValues(0f, HALF_DIAGONAL);
     new AlertDialog.Builder(/* context= */ this)
         .setTitle(R.string.periodic_vignette_options)
@@ -698,13 +663,12 @@ public final class ConfigurationActivity extends AppCompatActivity {
   private void controlBitmapOverlaySettings() {
     View dialogView =
         getLayoutInflater().inflate(R.layout.bitmap_overlay_options, /* root= */ null);
-    Button uriButton = checkNotNull(dialogView.findViewById(R.id.bitmap_overlay_uri));
+    Button uriButton = dialogView.findViewById(R.id.bitmap_overlay_uri);
     uriButton.setOnClickListener(
         (view ->
             selectLocalFile(
-                checkNotNull(overlayLocalFilePickerLauncher),
+                overlayLocalFilePickerLauncher, /* mimeTypes= */ new String[] {"image/*"})));
-                /* mimeTypes= */ new String[] {"image/*"})));
+    Slider alphaSlider = dialogView.findViewById(R.id.bitmap_overlay_alpha_slider);
-    Slider alphaSlider = checkNotNull(dialogView.findViewById(R.id.bitmap_overlay_alpha_slider));
     new AlertDialog.Builder(/* context= */ this)
         .setTitle(R.string.bitmap_overlay_settings)
         .setView(dialogView)
@@ -719,16 +683,16 @@ public final class ConfigurationActivity extends AppCompatActivity {
 
   private void controlTextOverlaySettings() {
     View dialogView = getLayoutInflater().inflate(R.layout.text_overlay_options, /* root= */ null);
-    EditText textEditText = checkNotNull(dialogView.findViewById(R.id.text_overlay_text));
+    EditText textEditText = dialogView.findViewById(R.id.text_overlay_text);
 
     ArrayAdapter<String> textColorAdapter =
         new ArrayAdapter<>(/* context= */ this, R.layout.spinner_item);
     textColorAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
-    Spinner textColorSpinner = checkNotNull(dialogView.findViewById(R.id.text_overlay_text_color));
+    Spinner textColorSpinner = dialogView.findViewById(R.id.text_overlay_text_color);
     textColorSpinner.setAdapter(textColorAdapter);
     textColorAdapter.addAll(OVERLAY_COLORS.keySet());
 
-    Slider alphaSlider = checkNotNull(dialogView.findViewById(R.id.text_overlay_alpha_slider));
+    Slider alphaSlider = dialogView.findViewById(R.id.text_overlay_alpha_slider);
     new AlertDialog.Builder(/* context= */ this)
         .setTitle(R.string.bitmap_overlay_settings)
         .setView(dialogView)
@@ -737,26 +701,13 @@ public final class ConfigurationActivity extends AppCompatActivity {
             (DialogInterface dialogInterface, int i) -> {
               textOverlayText = textEditText.getText().toString();
               String selectedTextColor = String.valueOf(textColorSpinner.getSelectedItem());
-              textOverlayTextColor = checkNotNull(OVERLAY_COLORS.get(selectedTextColor));
+              textOverlayTextColor = OVERLAY_COLORS.get(selectedTextColor);
               textOverlayAlpha = alphaSlider.getValue();
             })
         .create()
         .show();
   }
 
-  @RequiresNonNull({
-    "removeVideoCheckbox",
-    "forceAudioTrackCheckbox",
-    "audioMimeSpinner",
-    "videoMimeSpinner",
-    "resolutionHeightSpinner",
-    "scaleSpinner",
-    "rotateSpinner",
-    "enableDebugPreviewCheckBox",
-    "hdrModeSpinner",
-    "selectAudioEffectsButton",
-    "selectVideoEffectsButton"
-  })
   private void onRemoveAudio(View view) {
     if (((CheckBox) view).isChecked()) {
       removeVideoCheckbox.setChecked(false);
@@ -766,19 +717,6 @@ public final class ConfigurationActivity extends AppCompatActivity {
     }
   }
 
-  @RequiresNonNull({
-    "removeAudioCheckbox",
-    "forceAudioTrackCheckbox",
-    "audioMimeSpinner",
-    "videoMimeSpinner",
-    "resolutionHeightSpinner",
-    "scaleSpinner",
-    "rotateSpinner",
-    "enableDebugPreviewCheckBox",
-    "hdrModeSpinner",
-    "selectAudioEffectsButton",
-    "selectVideoEffectsButton"
-  })
   private void onRemoveVideo(View view) {
     if (((CheckBox) view).isChecked()) {
       removeAudioCheckbox.setChecked(false);
@@ -788,18 +726,6 @@ public final class ConfigurationActivity extends AppCompatActivity {
     }
   }
 
-  @RequiresNonNull({
-    "forceAudioTrackCheckbox",
-    "audioMimeSpinner",
-    "videoMimeSpinner",
-    "resolutionHeightSpinner",
-    "scaleSpinner",
-    "rotateSpinner",
-    "enableDebugPreviewCheckBox",
-    "hdrModeSpinner",
-    "selectAudioEffectsButton",
-    "selectVideoEffectsButton"
-  })
   private void enableTrackSpecificOptions(boolean isAudioEnabled, boolean isVideoEnabled) {
     forceAudioTrackCheckbox.setEnabled(isVideoEnabled);
     audioMimeSpinner.setEnabled(isAudioEnabled);

demos/transformer/src/main/java/androidx/media3/demo/transformer/TransformerActivity.java

@@ -112,8 +112,6 @@ import java.util.Arrays;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
-import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
-import org.checkerframework.checker.nullness.qual.RequiresNonNull;
 import org.json.JSONException;
 import org.json.JSONObject;
 
@@ -121,21 +119,21 @@ import org.json.JSONObject;
 public final class TransformerActivity extends AppCompatActivity {
   private static final String TAG = "TransformerActivity";
 
-  private @MonotonicNonNull Button displayInputButton;
+  private Button displayInputButton;
-  private @MonotonicNonNull MaterialCardView inputCardView;
+  private MaterialCardView inputCardView;
-  private @MonotonicNonNull TextView inputTextView;
+  private TextView inputTextView;
-  private @MonotonicNonNull ImageView inputImageView;
+  private ImageView inputImageView;
-  private @MonotonicNonNull PlayerView inputPlayerView;
+  private PlayerView inputPlayerView;
-  private @MonotonicNonNull PlayerView outputPlayerView;
+  private PlayerView outputPlayerView;
-  private @MonotonicNonNull TextView outputVideoTextView;
+  private TextView outputVideoTextView;
-  private @MonotonicNonNull TextView debugTextView;
+  private TextView debugTextView;
-  private @MonotonicNonNull TextView informationTextView;
+  private TextView informationTextView;
-  private @MonotonicNonNull ViewGroup progressViewGroup;
+  private ViewGroup progressViewGroup;
-  private @MonotonicNonNull LinearProgressIndicator progressIndicator;
+  private LinearProgressIndicator progressIndicator;
-  private @MonotonicNonNull Button cancelButton;
+  private Button cancelButton;
-  private @MonotonicNonNull Button resumeButton;
+  private Button resumeButton;
-  private @MonotonicNonNull Stopwatch exportStopwatch;
+  private Stopwatch exportStopwatch;
-  private @MonotonicNonNull AspectRatioFrameLayout debugFrame;
+  private AspectRatioFrameLayout debugFrame;
 
   @Nullable private DebugTextViewHelper debugTextViewHelper;
   @Nullable private ExoPlayer inputPlayer;
@@ -183,8 +181,8 @@ public final class TransformerActivity extends AppCompatActivity {
 
     startExport();
 
-    checkNotNull(inputPlayerView).onResume();
+    inputPlayerView.onResume();
-    checkNotNull(outputPlayerView).onResume();
+    outputPlayerView.onResume();
   }
 
   @Override
@@ -198,13 +196,13 @@ public final class TransformerActivity extends AppCompatActivity {
 
     // The stop watch is reset after cancelling the export, in case cancelling causes the stop watch
     // to be stopped in a transformer callback.
-    checkNotNull(exportStopwatch).reset();
+    exportStopwatch.reset();
 
-    checkNotNull(inputPlayerView).onPause();
+    inputPlayerView.onPause();
-    checkNotNull(outputPlayerView).onPause();
+    outputPlayerView.onPause();
     releasePlayer();
 
-    checkNotNull(outputFile).delete();
+    outputFile.delete();
     outputFile = null;
     if (oldOutputFile != null) {
       oldOutputFile.delete();
@@ -213,22 +211,6 @@ public final class TransformerActivity extends AppCompatActivity {
   }
 
   private void startExport() {
-    checkNotNull(progressIndicator);
-    checkNotNull(informationTextView);
-    checkNotNull(exportStopwatch);
-    checkNotNull(inputCardView);
-    checkNotNull(inputTextView);
-    checkNotNull(inputImageView);
-    checkNotNull(inputPlayerView);
-    checkNotNull(outputPlayerView);
-    checkNotNull(outputVideoTextView);
-    checkNotNull(debugTextView);
-    checkNotNull(progressViewGroup);
-    checkNotNull(debugFrame);
-    checkNotNull(displayInputButton);
-    checkNotNull(cancelButton);
-    checkNotNull(resumeButton);
-
     requestReadVideoPermission(/* activity= */ this);
 
     Intent intent = getIntent();
@@ -297,20 +279,6 @@ public final class TransformerActivity extends AppCompatActivity {
     return mediaItemBuilder.build();
   }
 
-  @RequiresNonNull({
-    "inputCardView",
-    "inputTextView",
-    "inputImageView",
-    "inputPlayerView",
-    "outputPlayerView",
-    "outputVideoTextView",
-    "displayInputButton",
-    "debugTextView",
-    "informationTextView",
-    "exportStopwatch",
-    "progressViewGroup",
-    "debugFrame",
-  })
   private Transformer createTransformer(@Nullable Bundle bundle, Uri inputUri, String filePath) {
     Transformer.Builder transformerBuilder =
         new Transformer.Builder(/* context= */ this)
@@ -380,12 +348,6 @@ public final class TransformerActivity extends AppCompatActivity {
     return file;
   }
 
-  @RequiresNonNull({
-    "inputCardView",
-    "outputPlayerView",
-    "exportStopwatch",
-    "progressViewGroup",
-  })
   private Composition createComposition(MediaItem mediaItem, @Nullable Bundle bundle) {
     EditedMediaItem.Builder editedMediaItemBuilder = new EditedMediaItem.Builder(mediaItem);
     // For image inputs. Automatically ignored if input is audio/video.
@@ -657,7 +619,7 @@ public final class TransformerActivity extends AppCompatActivity {
       BitmapOverlay bitmapOverlay =
           BitmapOverlay.createStaticBitmapOverlay(
               getApplicationContext(),
-              Uri.parse(checkNotNull(bundle.getString(ConfigurationActivity.BITMAP_OVERLAY_URI))),
+              Uri.parse(bundle.getString(ConfigurationActivity.BITMAP_OVERLAY_URI)),
               overlaySettings);
       overlaysBuilder.add(bitmapOverlay);
     }
@@ -668,8 +630,7 @@ public final class TransformerActivity extends AppCompatActivity {
                   bundle.getFloat(ConfigurationActivity.TEXT_OVERLAY_ALPHA, /* defaultValue= */ 1))
               .build();
       SpannableString overlayText =
-          new SpannableString(
+          new SpannableString(bundle.getString(ConfigurationActivity.TEXT_OVERLAY_TEXT));
-              checkNotNull(bundle.getString(ConfigurationActivity.TEXT_OVERLAY_TEXT)));
       overlayText.setSpan(
           new ForegroundColorSpan(bundle.getInt(ConfigurationActivity.TEXT_OVERLAY_TEXT_COLOR)),
           /* start= */ 0,
@@ -683,12 +644,6 @@ public final class TransformerActivity extends AppCompatActivity {
     return overlays.isEmpty() ? null : new OverlayEffect(overlays);
   }
 
-  @RequiresNonNull({
-    "informationTextView",
-    "progressViewGroup",
-    "debugFrame",
-    "exportStopwatch",
-  })
   private void onError(ExportException exportException) {
     exportStopwatch.stop();
     informationTextView.setText(R.string.export_error);
@@ -699,20 +654,6 @@ public final class TransformerActivity extends AppCompatActivity {
     Log.e(TAG, "Export error", exportException);
   }
 
-  @RequiresNonNull({
-    "inputCardView",
-    "inputTextView",
-    "inputImageView",
-    "inputPlayerView",
-    "outputPlayerView",
-    "outputVideoTextView",
-    "debugTextView",
-    "displayInputButton",
-    "informationTextView",
-    "progressViewGroup",
-    "debugFrame",
-    "exportStopwatch",
-  })
   private void onCompleted(Uri inputUri, String filePath, ExportResult exportResult) {
     exportStopwatch.stop();
     long elapsedTimeMs = exportStopwatch.elapsed(TimeUnit.MILLISECONDS);
@@ -748,14 +689,6 @@ public final class TransformerActivity extends AppCompatActivity {
     }
   }
 
-  @RequiresNonNull({
-    "inputCardView",
-    "inputTextView",
-    "inputImageView",
-    "inputPlayerView",
-    "outputPlayerView",
-    "debugTextView",
-  })
   private void playMediaItems(MediaItem inputMediaItem, MediaItem outputMediaItem) {
     inputPlayerView.setPlayer(null);
     outputPlayerView.setPlayer(null);
@@ -791,8 +724,8 @@ public final class TransformerActivity extends AppCompatActivity {
       ExoPlayer inputPlayer = new ExoPlayer.Builder(/* context= */ this).build();
       inputPlayerView.setPlayer(inputPlayer);
       inputPlayerView.setControllerAutoShow(false);
-      inputPlayerView.setOnClickListener(this::onClickingPlayerView);
+      inputPlayerView.setOnClickListener(this::handlePlayerViewClick);
-      outputPlayerView.setOnClickListener(this::onClickingPlayerView);
+      outputPlayerView.setOnClickListener(this::handlePlayerViewClick);
       inputPlayer.setMediaItem(inputMediaItem);
       inputPlayer.prepare();
       this.inputPlayer = inputPlayer;
@@ -805,21 +738,21 @@ public final class TransformerActivity extends AppCompatActivity {
     debugTextViewHelper.start();
   }
 
-  private void onClickingPlayerView(View view) {
+  private void handlePlayerViewClick(View view) {
     if (view == inputPlayerView) {
-      if (inputPlayer != null && inputTextView != null) {
+      if (inputPlayer != null) {
         inputPlayer.setVolume(1f);
         inputTextView.setText(R.string.input_video_playing_sound);
       }
-      checkNotNull(outputPlayer).setVolume(0f);
+      outputPlayer.setVolume(0f);
-      checkNotNull(outputVideoTextView).setText(R.string.output_video_no_sound);
+      outputVideoTextView.setText(R.string.output_video_no_sound);
     } else {
-      if (inputPlayer != null && inputTextView != null) {
+      if (inputPlayer != null) {
         inputPlayer.setVolume(0f);
         inputTextView.setText(getString(R.string.input_video_no_sound));
       }
-      checkNotNull(outputPlayer).setVolume(1f);
+      outputPlayer.setVolume(1f);
-      checkNotNull(outputVideoTextView).setText(R.string.output_video_playing_sound);
+      outputVideoTextView.setText(R.string.output_video_playing_sound);
     }
   }
 
@@ -850,10 +783,6 @@ public final class TransformerActivity extends AppCompatActivity {
     Toast.makeText(getApplicationContext(), getString(messageResource), Toast.LENGTH_LONG).show();
   }
 
-  @RequiresNonNull({
-    "inputCardView",
-    "displayInputButton",
-  })
   private void toggleInputVideoDisplay(View view) {
     if (inputCardView.getVisibility() == View.GONE) {
       inputCardView.setVisibility(View.VISIBLE);
@@ -867,7 +796,6 @@ public final class TransformerActivity extends AppCompatActivity {
     }
   }
 
-  @RequiresNonNull({"transformer", "exportStopwatch", "cancelButton", "resumeButton"})
   private void cancelExport(View view) {
     transformer.cancel();
     transformer = null;
@@ -882,7 +810,7 @@ public final class TransformerActivity extends AppCompatActivity {
 
   private final class DemoDebugViewProvider implements DebugViewProvider {
 
-    private @MonotonicNonNull SurfaceView surfaceView;
+    @Nullable private SurfaceView surfaceView;
     private int width;
     private int height;
 
@@ -909,7 +837,7 @@ public final class TransformerActivity extends AppCompatActivity {
       runOnUiThread(
           () -> {
             surfaceView = new SurfaceView(/* context= */ TransformerActivity.this);
-            AspectRatioFrameLayout debugFrame = checkNotNull(TransformerActivity.this.debugFrame);
+            AspectRatioFrameLayout debugFrame = TransformerActivity.this.debugFrame;
             debugFrame.addView(surfaceView);
             debugFrame.setAspectRatio((float) width / height);
             surfaceView