From f05db56f242da7a0bd3770d69eb816091b303d3d Mon Sep 17 00:00:00 2001
From: George Mount <mount@google.com>
Date: Wed, 1 Mar 2017 15:38:02 -0800
Subject: [PATCH] Fix NPE when combining pop with add transaction.

Bug 35832085

When pop transactions and an add transaction are acting
in the same frame, optimized tranactions can work properly,
but unoptimized transactions have no guarantees. This fixes
a crash with unoptimized transactions so they will at least
not break.

Test: I996f54ae2540f31134e6a9a28870826a73ea1610
Change-Id: I3890dd30e9aff70f4ac142773de8479f1a9dffc8
---
 core/java/android/app/FragmentTransition.java | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/core/java/android/app/FragmentTransition.java b/core/java/android/app/FragmentTransition.java
index f62ab8d76c3c9..780a9227cecca 100644
--- a/core/java/android/app/FragmentTransition.java
+++ b/core/java/android/app/FragmentTransition.java
@@ -780,8 +780,10 @@ class FragmentTransition {
             names = inTransaction.mSharedElementTargetNames;
         }
 
-        inSharedElements.retainAll(names);
-        if (sharedElementCallback != null) {
+        if (names != null) {
+            inSharedElements.retainAll(names);
+        }
+        if (names != null && sharedElementCallback != null) {
             sharedElementCallback.onMapSharedElements(names, inSharedElements);
             for (int i = names.size() - 1; i >= 0; i--) {
                 String name = names.get(i);
@@ -830,8 +832,9 @@ class FragmentTransition {
             FragmentContainerTransition fragments,
             Transition enterTransition, boolean inIsPop) {
         BackStackRecord inTransaction = fragments.lastInTransaction;
-        if (enterTransition != null && inTransaction.mSharedElementSourceNames != null &&
-                !inTransaction.mSharedElementSourceNames.isEmpty()) {
+        if (enterTransition != null && inSharedElements != null
+                && inTransaction.mSharedElementSourceNames != null
+                && !inTransaction.mSharedElementSourceNames.isEmpty()) {
             final String targetName = inIsPop
                     ? inTransaction.mSharedElementSourceNames.get(0)
                     : inTransaction.mSharedElementTargetNames.get(0);
@@ -1096,7 +1099,9 @@ class FragmentTransition {
         if (transition != null) {
             viewList = new ArrayList<>();
             View root = fragment.getView();
-            root.captureTransitioningViews(viewList);
+            if (root != null) {
+                root.captureTransitioningViews(viewList);
+            }
             if (sharedElements != null) {
                 viewList.removeAll(sharedElements);
             }