Tweaks to Activity up navigation

Be more explicit in docs about getParentActivityIntent and guard against
calls when a parent has not been declared in the manifest.

Move automatic up navigation to happen after dispatch of the menu
selection event of id android.R.id.home to fragments. (Last.)

Fixes bug 6305357

Change-Id: I944e5c40774121f9a28250d8d98da6aa646f9357

1 files changed, 23 insertions, 12 deletions

diff --git a/core/java/android/app/Activity.java b/core/java/android/app/Activity.java
index 3e123ba..7207e29 100644
--- a/core/java/android/app/Activity.java
+++ b/core/java/android/app/Activity.java
@@ -2522,7 +2522,19 @@ public class Activity extends ContextThemeWrapper
                 if (onOptionsItemSelected(item)) {
                     return true;
                 }
-                return mFragments.dispatchOptionsItemSelected(item);
+                if (mFragments.dispatchOptionsItemSelected(item)) {
+                    return true;
+                }
+                if (item.getItemId() == android.R.id.home && mActionBar != null &&
+                        (mActionBar.getDisplayOptions() & ActionBar.DISPLAY_HOME_AS_UP) != 0) {
+                    if (mParent == null) {
+                        onNavigateUp();
+                    } else {
+                        mParent.onNavigateUpFromChild(this);
+                    }
+                    return true;
+                }
+                return false;
                 
             case Window.FEATURE_CONTEXT_MENU:
                 EventLog.writeEvent(50000, 1, item.getTitleCondensed());
@@ -2654,15 +2666,6 @@ public class Activity extends ContextThemeWrapper
         if (mParent != null) {
             return mParent.onOptionsItemSelected(item);
         }
-        if (item.getItemId() == android.R.id.home && mActionBar != null &&
-                (mActionBar.getDisplayOptions() & ActionBar.DISPLAY_HOME_AS_UP) != 0) {
-            if (mParent == null) {
-                onNavigateUp();
-            } else {
-                mParent.onNavigateUpFromChild(this);
-            }
-            return true;
-        }
         return false;
     }
 
@@ -4865,11 +4868,19 @@ public class Activity extends ContextThemeWrapper
      * Obtain an {@link Intent} that will launch an explicit target activity specified by
      * this activity's logical parent. The logical parent is named in the application's manifest
      * by the {@link android.R.attr#parentActivityName parentActivityName} attribute.
+     * Activity subclasses may override this method to modify the Intent returned by
+     * super.getParentActivityIntent() or to implement a different mechanism of retrieving
+     * the parent intent entirely.
      *
-     * @return a new Intent targeting the defined parent of this activity
+     * @return a new Intent targeting the defined parent of this activity or null if
+     *         there is no valid parent.
      */
     public Intent getParentActivityIntent() {
-        return new Intent().setClassName(this, mActivityInfo.parentActivityName);
+        final String parentName = mActivityInfo.parentActivityName;
+        if (TextUtils.isEmpty(parentName)) {
+            return null;
+        }
+        return new Intent().setClassName(this, parentName);
     }
 
     // ------------------ Internal API ------------------