Fix PickerAndroid will reset selected value during items update.

ReactAndroid/src/main/java/com/facebook/react/views/picker/ReactPicker.java

@@ -13,6 +13,7 @@
 import android.view.View;
 import android.widget.AdapterView;
 import android.widget.Spinner;
+import android.widget.SpinnerAdapter;
 
 import com.facebook.react.common.annotations.VisibleForTesting;
 
@@ -23,6 +24,7 @@ public class ReactPicker extends AppCompatSpinner {
   private int mMode = Spinner.MODE_DIALOG;
   private @Nullable Integer mPrimaryColor;
   private @Nullable OnSelectListener mOnSelectListener;
+  private @Nullable SpinnerAdapter mStagedAdapter;
   private @Nullable Integer mStagedSelection;
 
   private final OnItemSelectedListener mItemSelectedListener = new OnItemSelectedListener() {
@@ -111,33 +113,42 @@ public void setOnSelectListener(@Nullable OnSelectListener onSelectListener) {
     return mOnSelectListener;
   }
 
+  /* package */ void setStagedAdapter(final SpinnerAdapter adapter) {
+   mStagedAdapter = adapter;
+  }
+
   /**
-   * Will cache "selection" value locally and set it only once {@link #updateStagedSelection} is
+   * Will cache "selection" value locally and set it only once {@link #commitStagedData} is
    * called
    */
-  public void setStagedSelection(int selection) {
+  /* package */ void setStagedSelection(int selection) {
     mStagedSelection = selection;
   }
 
-  public void updateStagedSelection() {
-    if (mStagedSelection != null) {
-      setSelectionWithSuppressEvent(mStagedSelection);
-      mStagedSelection = null;
-    }
-  }
-
   /**
-   * Set the selection while suppressing the follow-up {@link OnSelectListener#onItemSelected(int)}
-   * event. This is used so we don't get an event when changing the selection ourselves.
-   *
-   * @param position the position of the selected item
+   * Used to commit staged data into ReactPicker view.
+   * During this period, we will disable {@link OnSelectListener#onItemSelected(int)} temporarily,
+   * so we don't get an event when changing the items/selection ourselves.
    */
-  private void setSelectionWithSuppressEvent(int position) {
-    if (position != getSelectedItemPosition()) {
-      setOnItemSelectedListener(null);
-      setSelection(position, false);
-      setOnItemSelectedListener(mItemSelectedListener);
+  /* package */ void commitStagedData() {
+    setOnItemSelectedListener(null);
+
+    final int origSelection = getSelectedItemPosition();
+    if (mStagedAdapter != null && mStagedAdapter != getAdapter()) {
+      setAdapter(mStagedAdapter);
+      // After setAdapter(), Spinner will reset selection and cause unnecessary onValueChange event.
+      // Explicitly setup selection again to prevent this.
+      // Ref: https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/widget/AbsSpinner.java#123
+      setSelection(origSelection, false);
+      mStagedAdapter = null;
     }
+
+    if (mStagedSelection != null && mStagedSelection != origSelection) {
+      setSelection(mStagedSelection, false);
+      mStagedSelection = null;
+    }
+
+    setOnItemSelectedListener(mItemSelectedListener);
   }
 
   public @Nullable Integer getPrimaryColor() {

ReactAndroid/src/main/java/com/facebook/react/views/picker/ReactPickerManager.java

@@ -44,9 +44,9 @@ public void setItems(ReactPicker view, @Nullable ReadableArray items) {
       }
       ReactPickerAdapter adapter = new ReactPickerAdapter(view.getContext(), data);
       adapter.setPrimaryTextColor(view.getPrimaryColor());
-      view.setAdapter(adapter);
+      view.setStagedAdapter(adapter);
     } else {
-      view.setAdapter(null);
+      view.setStagedAdapter(null);
     }
   }
 
@@ -77,7 +77,7 @@ public void setSelected(ReactPicker view, int selected) {
   @Override
   protected void onAfterUpdateTransaction(ReactPicker view) {
     super.onAfterUpdateTransaction(view);
-    view.updateStagedSelection();
+    view.commitStagedData();
   }
 
   @Override