Add @Nullable annotations for simple cases

Add @Nullable annotations for the fields that are expected
to be null at arbitrary lifecycle time and are their usage
is protected by null checks.

Bug: 205828770
Test: m LauncherGoResLib
Change-Id: I9c31e1dc0d01cdd68dfff0a005ba1f40c257f8ea
(cherry picked from commit 920dc2f28f81ce2aec07477dfb6f4efd8f91e4ad)

go/quickstep/src/com/android/quickstep/views/GoOverviewActionsView.java

@@ -35,6 +35,7 @@ import com.android.quickstep.util.RecentsOrientedState;
  */
 public class GoOverviewActionsView extends OverviewActionsView<OverlayUICallbacksGo> {
 
+    @Nullable
     private ArrowTipView mArrowTipView;
 
     public GoOverviewActionsView(Context context) {

quickstep/src/com/android/quickstep/views/AllAppsEduView.java

@@ -35,6 +35,7 @@ import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.View;
 
+import androidx.annotation.Nullable;
 import androidx.core.graphics.ColorUtils;
 
 import com.android.launcher3.AbstractFloatingView;
@@ -58,6 +59,7 @@ public class AllAppsEduView extends AbstractFloatingView {
     private Launcher mLauncher;
     private AllAppsEduTouchController mTouchController;
 
+    @Nullable
     private AnimatorSet mAnimation;
 
     private GradientDrawable mCircle;

quickstep/src/com/android/quickstep/views/DigitalWellBeingToast.java

@@ -44,6 +44,7 @@ import android.view.ViewOutlineProvider;
 import android.widget.FrameLayout;
 import android.widget.TextView;
 
+import androidx.annotation.Nullable;
 import androidx.annotation.StringRes;
 
 import com.android.launcher3.BaseActivity;
@@ -69,6 +70,7 @@ public final class DigitalWellBeingToast {
     private Task mTask;
     private boolean mHasLimit;
     private long mAppRemainingTimeMs;
+    @Nullable
     private View mBanner;
     private ViewOutlineProvider mOldBannerOutlineProvider;
     private float mBannerOffsetPercentage;
@@ -234,7 +236,7 @@ public final class DigitalWellBeingToast {
                 task.titleDescription;
     }
 
-    private void replaceBanner(View view) {
+    private void replaceBanner(@Nullable View view) {
         resetOldBanner();
         setBanner(view);
     }
@@ -248,7 +250,7 @@ public final class DigitalWellBeingToast {
         }
     }
 
-    private void setBanner(View view) {
+    private void setBanner(@Nullable View view) {
         mBanner = view;
         if (view != null) {
             setupAndAddBanner();

quickstep/src/com/android/quickstep/views/FloatingWidgetBackgroundView.java

@@ -27,6 +27,8 @@ import android.view.View;
 import android.view.ViewOutlineProvider;
 import android.widget.RemoteViews.RemoteViewOutlineProvider;
 
+import androidx.annotation.Nullable;
+
 import com.android.launcher3.widget.LauncherAppWidgetHostView;
 import com.android.launcher3.widget.RoundedCornerEnforcement;
 
@@ -42,7 +44,9 @@ final class FloatingWidgetBackgroundView extends View {
     private final DrawableProperties mForegroundProperties = new DrawableProperties();
     private final DrawableProperties mBackgroundProperties = new DrawableProperties();
 
+    @Nullable
     private Drawable mOriginalForeground;
+    @Nullable
     private Drawable mOriginalBackground;
     private float mFinalRadius;
     private float mInitialOutlineRadius;
@@ -50,7 +54,7 @@ final class FloatingWidgetBackgroundView extends View {
     private boolean mIsUsingFallback;
     private View mSourceView;
 
-    FloatingWidgetBackgroundView(Context context, AttributeSet attrs, int defStyleAttr) {
+    FloatingWidgetBackgroundView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
         super(context, attrs, defStyleAttr);
         setOutlineProvider(new ViewOutlineProvider() {
             @Override
@@ -161,8 +165,10 @@ final class FloatingWidgetBackgroundView extends View {
 
     /** Stores and modifies a drawable's properties through an animation. */
     private static class DrawableProperties {
+        @Nullable
         private Drawable mDrawable;
         private float mOriginalRadius;
+        @Nullable
         private float[] mOriginalRadii;
         private final float[] mTmpRadii = new float[8];
 

quickstep/src/com/android/quickstep/views/FloatingWidgetView.java

@@ -57,10 +57,14 @@ public class FloatingWidgetView extends FrameLayout implements AnimatorListener,
     private LauncherAppWidgetHostView mAppWidgetView;
     private View mAppWidgetBackgroundView;
     private RectF mBackgroundPosition;
+    @Nullable
     private GhostView mForegroundOverlayView;
 
+    @Nullable
     private Runnable mEndRunnable;
+    @Nullable
     private Runnable mFastFinishRunnable;
+    @Nullable
     private Runnable mOnTargetChangeRunnable;
     private boolean mAppTargetIsTranslucent;
 

quickstep/src/com/android/quickstep/views/GroupedTaskView.java

@@ -39,10 +39,13 @@ import java.util.function.Consumer;
  */
 public class GroupedTaskView extends TaskView {
 
+    @Nullable
     private Task mSecondaryTask;
     private TaskThumbnailView mSnapshotView2;
     private IconView mIconView2;
+    @Nullable
     private CancellableTask<ThumbnailData> mThumbnailLoadRequest2;
+    @Nullable
     private CancellableTask mIconLoadRequest2;
     private final float[] mIcon2CenterCoords = new float[2];
     private TransformingTouchDelegate mIcon2TouchDelegate;
@@ -153,6 +156,7 @@ public class GroupedTaskView extends TaskView {
         }
     }
 
+    @Nullable
     @Override
     public RunnableList launchTaskAnimated() {
         getRecentsView().getSplitPlaceholder().launchTasks(mTask, mSecondaryTask,
@@ -167,7 +171,7 @@ public class GroupedTaskView extends TaskView {
     }
 
     @Override
-    void refreshThumbnails(HashMap<Integer, ThumbnailData> thumbnailDatas) {
+    void refreshThumbnails(@Nullable HashMap<Integer, ThumbnailData> thumbnailDatas) {
         super.refreshThumbnails(thumbnailDatas);
         if (mSecondaryTask != null && thumbnailDatas != null) {
             final ThumbnailData thumbnailData = thumbnailDatas.get(mSecondaryTask.key.id);

quickstep/src/com/android/quickstep/views/IconView.java

@@ -23,6 +23,8 @@ import android.util.AttributeSet;
 import android.view.Gravity;
 import android.view.View;
 
+import androidx.annotation.Nullable;
+
 import com.android.launcher3.Utilities;
 
 /**
@@ -31,6 +33,7 @@ import com.android.launcher3.Utilities;
  */
 public class IconView extends View {
 
+    @Nullable
     private Drawable mDrawable;
     private int mDrawableWidth, mDrawableHeight;
 
@@ -46,7 +49,10 @@ public class IconView extends View {
         super(context, attrs, defStyleAttr);
     }
 
-    public void setDrawable(Drawable d) {
+    /**
+     * Sets a {@link Drawable} to be displayed.
+     */
+    public void setDrawable(@Nullable Drawable d) {
         if (mDrawable != null) {
             mDrawable.setCallback(null);
         }
@@ -76,6 +82,7 @@ public class IconView extends View {
         mDrawable.setBounds(drawableRect);
     }
 
+    @Nullable
     public Drawable getDrawable() {
         return mDrawable;
     }

quickstep/src/com/android/quickstep/views/OverviewActionsView.java

@@ -90,8 +90,10 @@ public class OverviewActionsView<T extends OverlayUICallbacks> extends FrameLayo
     @ActionsDisabledFlags
     protected int mDisabledFlags;
 
+    @Nullable
     protected T mCallbacks;
 
+    @Nullable
     protected DeviceProfile mDp;
 
     public OverviewActionsView(Context context) {

quickstep/src/com/android/quickstep/views/SplitPlaceholderView.java

@@ -40,6 +40,7 @@ public class SplitPlaceholderView extends FrameLayout {
                 }
             };
 
+    @Nullable
     private IconView mIconView;
 
     public SplitPlaceholderView(Context context, AttributeSet attrs) {

quickstep/src/com/android/quickstep/views/TaskMenuView.java

@@ -39,6 +39,8 @@ import android.view.ViewTreeObserver.OnScrollChangedListener;
 import android.widget.LinearLayout;
 import android.widget.TextView;
 
+import androidx.annotation.Nullable;
+
 import com.android.launcher3.AbstractFloatingView;
 import com.android.launcher3.BaseDraggingActivity;
 import com.android.launcher3.DeviceProfile;
@@ -67,6 +69,7 @@ public class TaskMenuView extends AbstractFloatingView implements OnScrollChange
 
     private BaseDraggingActivity mActivity;
     private TextView mTaskName;
+    @Nullable
     private AnimatorSet mOpenCloseAnimator;
     private TaskView mTaskView;
     private TaskIdAttributeContainer mTaskContainer;

quickstep/src/com/android/quickstep/views/TaskThumbnailView.java

@@ -78,6 +78,7 @@ public class TaskThumbnailView extends View {
             };
 
     private final BaseActivity mActivity;
+    @Nullable
     private TaskOverlay mOverlay;
     private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
     private final Paint mBackgroundPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
@@ -90,8 +91,11 @@ public class TaskThumbnailView extends View {
     private final PreviewPositionHelper mPreviewPositionHelper = new PreviewPositionHelper();
     private TaskView.FullscreenDrawParams mFullscreenParams;
 
+    @Nullable
     private Task mTask;
+    @Nullable
     private ThumbnailData mThumbnailData;
+    @Nullable
     protected BitmapShader mBitmapShader;
 
     /** How much this thumbnail is dimmed, 0 not dimmed at all, 1 totally dimmed. */
@@ -141,7 +145,8 @@ public class TaskThumbnailView extends View {
      *                   upon swipe up so that a usable screenshot is accessible immediately when
      *                   recents animation needs to be finished / cancelled.
      */
-    public void setThumbnail(Task task, ThumbnailData thumbnailData, boolean refreshNow) {
+    public void setThumbnail(@Nullable Task task, @Nullable ThumbnailData thumbnailData,
+            boolean refreshNow) {
         mTask = task;
         mThumbnailData =
                 (thumbnailData != null && thumbnailData.thumbnail != null) ? thumbnailData : null;
@@ -151,7 +156,7 @@ public class TaskThumbnailView extends View {
     }
 
     /** See {@link #setThumbnail(Task, ThumbnailData, boolean)} */
-    public void setThumbnail(Task task, ThumbnailData thumbnailData) {
+    public void setThumbnail(@Nullable Task task, @Nullable ThumbnailData thumbnailData) {
         setThumbnail(task, thumbnailData, true /* refreshNow */);
     }
 
@@ -366,6 +371,10 @@ public class TaskThumbnailView extends View {
         return Utilities.makeColorTintingColorFilter(mDimColor, dimAmount);
     }
 
+    /**
+     * Returns current thumbnail or null if none is set.
+     */
+    @Nullable
     public Bitmap getThumbnail() {
         if (mThumbnailData == null) {
             return null;

quickstep/src/com/android/quickstep/views/TaskView.java

@@ -360,6 +360,7 @@ public class TaskView extends FrameLayout implements Reusable {
 
     private final TaskOutlineProvider mOutlineProvider;
 
+    @Nullable
     protected Task mTask;
     protected TaskThumbnailView mSnapshotView;
     protected IconView mIconView;
@@ -394,6 +395,7 @@ public class TaskView extends FrameLayout implements Reusable {
     private float mSplitSelectTranslationX;
     private float mSplitSelectScrollOffsetPrimary;
 
+    @Nullable
     private ObjectAnimator mIconAndDimAnimator;
     private float mIconScaleAnimStartProgress = 0;
     private float mFocusTransitionProgress = 1;
@@ -411,7 +413,9 @@ public class TaskView extends FrameLayout implements Reusable {
     private boolean mShowScreenshot;
 
     // The current background requests to load the task thumbnail and icon
+    @Nullable
     private CancellableTask mThumbnailLoadRequest;
+    @Nullable
     private CancellableTask mIconLoadRequest;
 
     private boolean mEndQuickswitchCuj;
@@ -544,6 +548,7 @@ public class TaskView extends FrameLayout implements Reusable {
         return mTaskIdAttributeContainer;
     }
 
+    @Nullable
     public Task getTask() {
         return mTask;
     }
@@ -686,6 +691,7 @@ public class TaskView extends FrameLayout implements Reusable {
      * Starts the task associated with this view and animates the startup.
      * @return CompletionStage to indicate the animation completion or null if the launch failed.
      */
+    @Nullable
     public RunnableList launchTaskAnimated() {
         if (mTask != null) {
             TestLogging.recordEvent(
@@ -843,7 +849,7 @@ public class TaskView extends FrameLayout implements Reusable {
         }
     }
 
-    protected void setIcon(IconView iconView, Drawable icon) {
+    protected void setIcon(IconView iconView, @Nullable Drawable icon) {
         if (icon != null) {
             iconView.setDrawable(icon);
             iconView.setOnClickListener(v -> {