Throw a more descriptive exception when adding null to a ViewGroup

Help developers during debugging bad calls to addView by throwing an
IllegalArgumentException earlier rather than implicitly tossing NPE
the first time the child view is accessed.

Change-Id: I4a554635815a5d0b415f637b93592fb45973f26d

1 files changed, 10 insertions, 0 deletions

diff --git a/core/java/android/view/ViewGroup.java b/core/java/android/view/ViewGroup.java
index 3a183ed6707b..2921cfaa03b4 100644
--- a/core/java/android/view/ViewGroup.java
+++ b/core/java/android/view/ViewGroup.java
@@ -3671,6 +3671,9 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager
      * @see #generateDefaultLayoutParams()
      */
     public void addView(View child, int index) {
+        if (child == null) {
+            throw new IllegalArgumentException("Cannot add a null child view to a ViewGroup");
+        }
         LayoutParams params = child.getLayoutParams();
         if (params == null) {
             params = generateDefaultLayoutParams();
@@ -3728,6 +3731,10 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager
             System.out.println(this + " addView");
         }
 
+        if (child == null) {
+            throw new IllegalArgumentException("Cannot add a null child view to a ViewGroup");
+        }
+
         // addViewInner() will call child.requestLayout() when setting the new LayoutParams
         // therefore, we call requestLayout() on ourselves before, so that the child's request
         // will be blocked at our level
@@ -3855,6 +3862,9 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager
      */
     protected boolean addViewInLayout(View child, int index, LayoutParams params,
             boolean preventRequestLayout) {
+        if (child == null) {
+            throw new IllegalArgumentException("Cannot add a null child view to a ViewGroup");
+        }
         child.mParent = null;
         addViewInner(child, index, params, preventRequestLayout);
         child.mPrivateFlags = (child.mPrivateFlags & ~PFLAG_DIRTY_MASK) | PFLAG_DRAWN;