[android] don't delete local reference on value copy

2 files changed, 32 insertions, 19 deletions

diff --git a/platform/android/src/style/value.cpp b/platform/android/src/style/value.cpp
index c03dd39132..c8aad1682b 100644
--- a/platform/android/src/style/value.cpp
+++ b/platform/android/src/style/value.cpp
@@ -5,65 +5,76 @@
 namespace mbgl {
 namespace android {
 
+    class ObjectDeleter {
+    public:
+        ObjectDeleter() = default;
+        ObjectDeleter(JNIEnv& e) : env(e) {}
+
+        void operator()(jni::jobject* p) const {
+          if (p) {
+              jni::DeleteLocalRef(env, p);
+          }
+        }
+
+    private:
+        JNIEnv& env;
+    };
+
     //Instance
 
-    Value::Value(jni::JNIEnv& env, jni::jobject* _value) : jenv(env), value(_value) {}
+    Value::Value(jni::JNIEnv& env, jni::jobject* _value) : jenv(env), value(_value, ObjectDeleter(env)) {}
 
-    Value::~Value() {
-        if (value) {
-            jni::DeleteLocalRef(jenv, value);
-        }
-    }
+    Value::~Value() = default;
 
     bool Value::isNull() const {
         return value == nullptr;
     }
 
     bool Value::isArray() const {
-        return jni::IsInstanceOf(jenv, value, *java::ObjectArray::jclass);
+        return jni::IsInstanceOf(jenv, value.get(), *java::ObjectArray::jclass);
     }
 
     bool Value::isObject() const {
-        return jni::IsInstanceOf(jenv, value, *java::Map::jclass);;
+        return jni::IsInstanceOf(jenv, value.get(), *java::Map::jclass);;
     }
 
     bool Value::isString() const {
-        return jni::IsInstanceOf(jenv, value, *java::String::jclass);
+        return jni::IsInstanceOf(jenv, value.get(), *java::String::jclass);
     }
 
     bool Value::isBool() const {
-        return jni::IsInstanceOf(jenv, value, *java::Boolean::jclass);
+        return jni::IsInstanceOf(jenv, value.get(), *java::Boolean::jclass);
     }
 
     bool Value::isNumber() const {
-        return jni::IsInstanceOf(jenv, value, *java::Number::jclass);
+        return jni::IsInstanceOf(jenv, value.get(), *java::Number::jclass);
     }
 
     std::string Value::toString() const {
-        jni::jstring* string = reinterpret_cast<jni::jstring*>(value);
+        jni::jstring* string = reinterpret_cast<jni::jstring*>(value.get());
         return jni::Make<std::string>(jenv, jni::String(string));
     }
 
     float Value::toNumber() const {
-        return jni::CallMethod<jni::jfloat>(jenv, value, *java::Number::floatValueMethodId);
+        return jni::CallMethod<jni::jfloat>(jenv, value.get(), *java::Number::floatValueMethodId);
     }
 
     bool Value::toBool() const {
-        return jni::CallMethod<jni::jboolean>(jenv, value, *java::Boolean::booleanValueMethodId);
+        return jni::CallMethod<jni::jboolean>(jenv, value.get(), *java::Boolean::booleanValueMethodId);
     }
 
     Value Value::get(const char* key) const {
-        jni::jobject* member = jni::CallMethod<jni::jobject*>(jenv, value, *java::Map::getMethodId, jni::Make<jni::String>(jenv, std::string(key)).Get());
+        jni::jobject* member = jni::CallMethod<jni::jobject*>(jenv, value.get(), *java::Map::getMethodId, jni::Make<jni::String>(jenv, std::string(key)).Get());
         return Value(jenv, member);
     }
 
     int Value::getLength() const {
-        auto array = (jni::jarray<jni::jobject>*) value;
+        auto array = (jni::jarray<jni::jobject>*) value.get();
         return jni::GetArrayLength(jenv, *array);
     }
 
     Value Value::get(const int index ) const {
-        auto array = (jni::jarray<jni::jobject>*) value;
+        auto array = (jni::jarray<jni::jobject>*) value.get();
         return Value(jenv, jni::GetObjectArrayElement(jenv, *array, index));
     }
 }
diff --git a/platform/android/src/style/value.hpp b/platform/android/src/style/value.hpp
index 2f0b1d9706..461fc1a033 100644
--- a/platform/android/src/style/value.hpp
+++ b/platform/android/src/style/value.hpp
@@ -7,7 +7,7 @@
 namespace mbgl {
 namespace android {
 
-class Value  {
+class Value {
 public:
 
     Value(jni::JNIEnv&, jni::jobject*);
@@ -27,8 +27,10 @@ public:
     int getLength() const;
     Value get(const int index ) const;
 
+private:
+
     jni::JNIEnv& jenv;
-    jni::jobject* value;
+    std::shared_ptr<jni::jobject> value;
 };
 
 }