More detailed error reporting for AbsListView/CHOICE_MODE_MULTIPLE_MODAL

Throw a more descriptive exception when an app has not set a
multi-choice mode listener and an item becomes checked.

Change-Id: Ib682fd7a467a3751bb81dacbd22676aaa4407d36

Author: adamp

core/java/android/widget/AbsListView.java

@@ -973,6 +973,12 @@ public void setItemChecked(int position, boolean value) {
 
         // Start selection mode if needed. We don't need to if we're unchecking something.
         if (value && mChoiceMode == CHOICE_MODE_MULTIPLE_MODAL && mChoiceActionMode == null) {
+            if (mMultiChoiceModeCallback == null ||
+                    !mMultiChoiceModeCallback.hasWrappedCallback()) {
+                throw new IllegalStateException("AbsListView: attempted to start selection mode " +
+                        "for CHOICE_MODE_MULTIPLE_MODAL but no choice mode callback was " +
+                        "supplied. Call setMultiChoiceModeListener to set a callback.");
+            }
             mChoiceActionMode = startActionMode(mMultiChoiceModeCallback);
         }
 
@@ -5945,6 +5951,10 @@ public void setWrapped(MultiChoiceModeListener wrapped) {
             mWrapped = wrapped;
         }
 
+        public boolean hasWrappedCallback() {
+            return mWrapped != null;
+        }
+
         public boolean onCreateActionMode(ActionMode mode, Menu menu) {
             if (mWrapped.onCreateActionMode(mode, menu)) {
                 // Initialize checked graphic state?