Fix null pointer exception in year picker

Retain year picker position offset on orientation change

Bug: 8658299
Bug: 8581974
Change-Id: Ib21c5235be29f9143788b22fbd25d62538203265

2 files changed, 30 insertions, 21 deletions

diff --git a/src/com/android/datetimepicker/date/DatePickerDialog.java b/src/com/android/datetimepicker/date/DatePickerDialog.java
index 77bedbf..8954c35 100644
--- a/src/com/android/datetimepicker/date/DatePickerDialog.java
+++ b/src/com/android/datetimepicker/date/DatePickerDialog.java
@@ -67,6 +67,7 @@ public class DatePickerDialog extends DialogFragment implements
     private static final String KEY_YEAR_START = "year_start";
     private static final String KEY_YEAR_END = "year_end";
     private static final String KEY_CURRENT_VIEW = "current_view";
+    private static final String KEY_LIST_POSITION_OFFSET = "list_position_offset";
 
     private static final int DEFAULT_START_YEAR = 1900;
     private static final int DEFAULT_END_YEAR = 2100;
@@ -181,6 +182,7 @@ public class DatePickerDialog extends DialogFragment implements
             listPosition = mDayPickerView.getMostVisiblePosition();
         } else if (mCurrentView == YEAR_VIEW) {
             listPosition = mYearPickerView.getFirstVisiblePosition();
+            outState.putInt(KEY_LIST_POSITION_OFFSET, mYearPickerView.getFirstPositionOffset());
         }
         outState.putInt(KEY_LIST_POSITION, listPosition);
     }
@@ -202,6 +204,7 @@ public class DatePickerDialog extends DialogFragment implements
         mYearView.setOnClickListener(this);
 
         int listPosition = -1;
+        int listPositionOffset = 0;
         int currentView = MONTH_AND_DAY_VIEW;
         if (savedInstanceState != null) {
             mWeekStart = savedInstanceState.getInt(KEY_WEEK_START);
@@ -209,6 +212,7 @@ public class DatePickerDialog extends DialogFragment implements
             mMaxYear = savedInstanceState.getInt(KEY_YEAR_END);
             currentView = savedInstanceState.getInt(KEY_CURRENT_VIEW);
             listPosition = savedInstanceState.getInt(KEY_LIST_POSITION);
+            listPositionOffset = savedInstanceState.getInt(KEY_LIST_POSITION_OFFSET);
         }
 
         final Activity activity = getActivity();
@@ -248,7 +252,7 @@ public class DatePickerDialog extends DialogFragment implements
             if (currentView == MONTH_AND_DAY_VIEW) {
                 mDayPickerView.postSetSelection(listPosition);
             } else if (currentView == YEAR_VIEW) {
-                mYearPickerView.postSetSelection(listPosition);
+                mYearPickerView.postSetSelectionFromTop(listPosition, listPositionOffset);
             }
         }
         return view;
diff --git a/src/com/android/datetimepicker/date/YearPickerView.java b/src/com/android/datetimepicker/date/YearPickerView.java
index 465b759..411c574 100644
--- a/src/com/android/datetimepicker/date/YearPickerView.java
+++ b/src/com/android/datetimepicker/date/YearPickerView.java
@@ -79,15 +79,19 @@ public class YearPickerView extends ListView implements OnItemClickListener, OnD
     public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
         mController.tryVibrate();
         TextViewWithCircularIndicator clickedView = (TextViewWithCircularIndicator) view;
-        if (mSelectedView != clickedView) {
-            mSelectedView.drawIndicator(false);
-            mSelectedView.requestLayout();
-            clickedView.drawIndicator(true);
-            clickedView.requestLayout();
-            mSelectedView = clickedView;
+        if (clickedView != null) {
+            if (clickedView != mSelectedView) {
+                if (mSelectedView != null) {
+                    mSelectedView.drawIndicator(false);
+                    mSelectedView.requestLayout();
+                }
+                clickedView.drawIndicator(true);
+                clickedView.requestLayout();
+                mSelectedView = clickedView;
+            }
+            mController.onYearSelected(getYearFromTextView(clickedView));
+            mAdapter.notifyDataSetChanged();
         }
-        mController.onYearSelected(getYearFromTextView(clickedView));
-        mAdapter.notifyDataSetChanged();
     }
 
     private int getYearFromTextView(TextView view) {
@@ -115,31 +119,32 @@ public class YearPickerView extends ListView implements OnItemClickListener, OnD
         }
     }
 
-    public void postSetSelection(final int position) {
-        post(new Runnable() {
-
-            @Override
-            public void run() {
-                setSelection(position);
-                requestLayout();
-            }
-        });
+    public void postSetSelectionCentered(final int position) {
+        postSetSelectionFromTop(position, mViewSize / 2 - mChildSize / 2);
     }
 
-    public void postSetSelectionFromTop(final int position) {
+    public void postSetSelectionFromTop(final int position, final int offset) {
         post(new Runnable() {
 
             @Override
             public void run() {
-                setSelectionFromTop(position, mViewSize / 2 - mChildSize / 2);
+                setSelectionFromTop(position, offset);
                 requestLayout();
             }
         });
     }
 
+    public int getFirstPositionOffset() {
+        final View firstChild = getChildAt(0);
+        if (firstChild == null) {
+            return 0;
+        }
+        return firstChild.getTop();
+    }
+
     @Override
     public void onDateChanged() {
         mAdapter.notifyDataSetChanged();
-        postSetSelectionFromTop(mController.getSelectedDay().year - mController.getMinYear());
+        postSetSelectionCentered(mController.getSelectedDay().year - mController.getMinYear());
     }
 }