ahat: Target Java 1.7.

So that users can run ahat with Java 7 without getting unsupported
major/minor version errors.

Change-Id: I76faab19bc1b14c76d5fd6b3ba19fcb07855dfd9
Test: m ahat-test
Test: /usr/local/buildtools/java/jdk7/bin/java -jar ahat.jar
Test: /usr/local/buildtools/java/jdk8/bin/java -jar ahat.jar
Bug: 28303627
diff --git a/tools/ahat/Android.mk b/tools/ahat/Android.mk
index 834426d..60e0cd8 100644
--- a/tools/ahat/Android.mk
+++ b/tools/ahat/Android.mk
@@ -30,6 +30,10 @@
 LOCAL_IS_HOST_MODULE := true
 LOCAL_MODULE_TAGS := optional
 LOCAL_MODULE := ahat
+
+# Let users with Java 7 run ahat (b/28303627)
+LOCAL_JAVA_LANGUAGE_VERSION := 1.7
+
 include $(BUILD_HOST_JAVA_LIBRARY)
 
 # --- ahat script ----------------
diff --git a/tools/ahat/src/AhatSnapshot.java b/tools/ahat/src/AhatSnapshot.java
index e6f8411..a8205c7 100644
--- a/tools/ahat/src/AhatSnapshot.java
+++ b/tools/ahat/src/AhatSnapshot.java
@@ -86,7 +86,7 @@
     mSnapshot = snapshot;
     mHeaps = new ArrayList<Heap>(mSnapshot.getHeaps());
 
-    ClassObj javaLangClass = mSnapshot.findClass("java.lang.Class");
+    final ClassObj javaLangClass = mSnapshot.findClass("java.lang.Class");
     for (Heap heap : mHeaps) {
       // Use a single element array for the total to act as a reference to a
       // long.