8 files changed, 150 insertions, 2 deletions
diff --git a/platform/android/src/gson/json_array.cpp b/platform/android/src/gson/json_array.cpp
index d91e323ac9..e8852d77e9 100644
--- a/platform/android/src/gson/json_array.cpp
+++ b/platform/android/src/gson/json_array.cpp
@@ -6,7 +6,22 @@ namespace mbgl {
 namespace android {
 namespace gson {
 
-std::vector<mapbox::geometry::value> JsonArray::convert(jni::JNIEnv &env, jni::Object<JsonArray> jsonArray) {
+jni::Object<JsonArray> JsonArray::New(jni::JNIEnv& env, const std::vector<mapbox::geometry::value>& values){
+    static auto constructor = JsonArray::javaClass.GetConstructor(env);
+    static auto addMethod = JsonArray::javaClass.GetMethod<void (jni::Object<JsonElement>)>(env, "add");
+
+    auto jsonArray = JsonArray::javaClass.New(env, constructor);
+
+    for (const auto &v : values) {
+        auto jsonElement = JsonElement::New(env, v);
+        jsonArray.Call(env, addMethod, jsonElement);
+        jni::DeleteLocalRef(env, jsonElement);
+    }
+
+    return jsonArray;
+}
+
+std::vector<mapbox::geometry::value> JsonArray::convert(jni::JNIEnv& env, const jni::Object<JsonArray> jsonArray) {
     std::vector<mapbox::geometry::value> values;
 
     if (jsonArray) {
@@ -28,7 +43,7 @@ std::vector<mapbox::geometry::value> JsonArray::convert(jni::JNIEnv &env, jni::O
     return values;
 }
 
-void JsonArray::registerNative(jni::JNIEnv &env) {
+void JsonArray::registerNative(jni::JNIEnv& env) {
     // Lookup the class
     javaClass = *jni::Class<JsonArray>::Find(env).NewGlobalRef(env).release();
 }
diff --git a/platform/android/src/gson/json_array.hpp b/platform/android/src/gson/json_array.hpp
index 8571ad5dba..c9ae98692f 100644
--- a/platform/android/src/gson/json_array.hpp
+++ b/platform/android/src/gson/json_array.hpp
@@ -13,6 +13,8 @@ class JsonArray : private mbgl::util::noncopyable {
 public:
     static constexpr auto Name() { return "com/google/gson/JsonArray"; };
 
+    static jni::Object<JsonArray> New(jni::JNIEnv&, const std::vector<mapbox::geometry::value>&);
+
     static std::vector<mapbox::geometry::value> convert(JNIEnv&, jni::Object<JsonArray>);
 
     static jni::Class<JsonArray> javaClass;
diff --git a/platform/android/src/gson/json_element.cpp b/platform/android/src/gson/json_element.cpp
index 060b1e0fe2..5eaaf531f4 100644
--- a/platform/android/src/gson/json_element.cpp
+++ b/platform/android/src/gson/json_element.cpp
@@ -11,6 +11,34 @@ namespace mbgl {
 namespace android {
 namespace gson {
 
+/**
+ * Turn mapbox::geometry::value into Java Gson JsonElement
+ */
+class JsonElementEvaluator {
+public:
+
+    jni::JNIEnv& env;
+
+    jni::Object<JsonElement> operator()(const JsonPrimitive::value value) const {
+        return jni::Cast(env, JsonPrimitive::New(env, value), JsonElement::javaClass);
+    }
+
+    jni::Object<JsonElement> operator()(const std::vector<mapbox::geometry::value> &values) const {
+        return jni::Cast(env, JsonArray::New(env, values), JsonElement::javaClass);
+    }
+
+    jni::Object<JsonElement> operator()(const std::unordered_map<std::string, mapbox::geometry::value> &values) const {
+        return jni::Cast(env, JsonObject::New(env, values), JsonElement::javaClass);
+    }
+
+};
+
+
+jni::Object<JsonElement> JsonElement::New(jni::JNIEnv& env, const mapbox::geometry::value& value) {
+  JsonElementEvaluator evaluator { env } ;
+  return mapbox::geometry::value::visit(value, evaluator);
+}
+
 mapbox::geometry::value JsonElement::convert(jni::JNIEnv &env, jni::Object<JsonElement> jsonElement) {
     mapbox::geometry::value value;
 
diff --git a/platform/android/src/gson/json_element.hpp b/platform/android/src/gson/json_element.hpp
index 7619350617..d850caa526 100644
--- a/platform/android/src/gson/json_element.hpp
+++ b/platform/android/src/gson/json_element.hpp
@@ -13,6 +13,8 @@ class JsonElement : private mbgl::util::noncopyable {
 public:
     static constexpr auto Name() { return "com/google/gson/JsonElement"; };
 
+    static jni::Object<JsonElement> New(jni::JNIEnv&, const mapbox::geometry::value&);
+
     static mapbox::geometry::value convert(JNIEnv&, jni::Object<JsonElement>);
 
     static bool isJsonObject(JNIEnv&, jni::Object<JsonElement>);
diff --git a/platform/android/src/gson/json_object.cpp b/platform/android/src/gson/json_object.cpp
index a704dae9dd..61b55f8b9e 100644
--- a/platform/android/src/gson/json_object.cpp
+++ b/platform/android/src/gson/json_object.cpp
@@ -9,6 +9,23 @@ namespace android {
 namespace gson {
 
 
+jni::Object<JsonObject> JsonObject::New(jni::JNIEnv& env, const std::unordered_map<std::string, mapbox::geometry::value>& values) {
+    static auto constructor = JsonObject::javaClass.GetConstructor(env);
+    static auto addMethod = JsonObject::javaClass.GetMethod<void (jni::String, jni::Object<JsonElement>)>(env, "add");
+
+    jni::Object<JsonObject> jsonObject = JsonObject::javaClass.New(env, constructor);
+
+    for (auto &item : values) {
+        jni::Object<JsonElement> jsonElement = JsonElement::New(env, item.second);
+        jni::String key = jni::Make<jni::String>(env, item.first);
+        jsonObject.Call(env, addMethod, key, jsonElement);
+        jni::DeleteLocalRef(env, jsonElement);
+        jni::DeleteLocalRef(env, key);
+    }
+
+    return jsonObject;
+}
+
 template <typename F> // void (jni::String, jni::Object<gson::JsonElement>)
 static void iterateEntrySet(jni::JNIEnv& env, jni::Object<JsonObject> jsonObject, F callback) {
     // Get Set<Map.Entry<String, JsonElement>>
diff --git a/platform/android/src/gson/json_object.hpp b/platform/android/src/gson/json_object.hpp
index aba8e40415..4bc61e51a2 100644
--- a/platform/android/src/gson/json_object.hpp
+++ b/platform/android/src/gson/json_object.hpp
@@ -13,6 +13,8 @@ class JsonObject : private mbgl::util::noncopyable {
 public:
     static constexpr auto Name() { return "com/google/gson/JsonObject"; };
 
+    static jni::Object<JsonObject> New(jni::JNIEnv&, const std::unordered_map<std::string, mapbox::geometry::value>&);
+
     static mapbox::geometry::property_map convert(JNIEnv&, jni::Object<JsonObject>);
 
     static jni::Class<JsonObject> javaClass;
diff --git a/platform/android/src/gson/json_primitive.cpp b/platform/android/src/gson/json_primitive.cpp
index 58d0b45fe7..4e171c4845 100644
--- a/platform/android/src/gson/json_primitive.cpp
+++ b/platform/android/src/gson/json_primitive.cpp
@@ -1,9 +1,89 @@
 #include "json_primitive.hpp"
+#include "../java/lang.hpp"
 
 namespace mbgl {
 namespace android {
 namespace gson {
 
+/**
+ * Turn mapbox::geometry::value into Java Gson JsonPrimitives
+ */
+class JsonPrimitiveEvaluator {
+public:
+
+    jni::JNIEnv& env;
+
+    /**
+     * Create a null primitive
+     */
+    jni::Object<JsonPrimitive> operator()(const mapbox::geometry::null_value_t) const {
+        return jni::Object<JsonPrimitive>();
+    }
+
+    /**
+     * Create a primitive containing a string value
+     */
+    jni::Object<JsonPrimitive> operator()(const std::string value) const {
+        static auto constructor = JsonPrimitive::javaClass.GetConstructor<jni::String>(env);
+        auto jvalue = jni::Make<jni::String>(env, value);
+        auto jsonPrimitive = JsonPrimitive::javaClass.New(env, constructor, jvalue);
+        jni::DeleteLocalRef(env, jvalue);
+        return jsonPrimitive;
+    }
+
+    /**
+     * Create a primitive containing a number value with type double
+     */
+    jni::Object<JsonPrimitive> operator()(const double value) const {
+        static auto constructor = JsonPrimitive::javaClass.GetConstructor<jni::Object<java::lang::Number>>(env);
+        auto boxedValue = java::lang::Double::valueOf(env, value);
+        auto number = jni::Cast(env, boxedValue, java::lang::Number::javaClass);
+        auto jsonPrimitive = JsonPrimitive::javaClass.New(env, constructor, number);
+        jni::DeleteLocalRef(env, boxedValue);
+        return jsonPrimitive;
+    }
+
+    /**
+     * Create a primitive containing a number value with type long
+     */
+    jni::Object<JsonPrimitive> operator()(const int64_t value) const {
+        static auto constructor = JsonPrimitive::javaClass.GetConstructor<jni::Object<java::lang::Number>>(env);
+        auto boxedValue = java::lang::Long::valueOf(env, value);
+        auto number = jni::Cast(env, boxedValue, java::lang::Number::javaClass);
+        auto jsonPrimitive =  JsonPrimitive::javaClass.New(env, constructor, number);
+        jni::DeleteLocalRef(env, boxedValue);
+        return jsonPrimitive;
+    }
+
+    /**
+     * Create a primitive containing a number value with type long
+     */
+    jni::Object<JsonPrimitive> operator()(const uint64_t value) const {
+        static auto constructor = JsonPrimitive::javaClass.GetConstructor<jni::Object<java::lang::Number>>(env);
+        auto boxedValue = java::lang::Long::valueOf(env, value);
+        auto number = jni::Cast(env, boxedValue, java::lang::Number::javaClass);
+        auto jsonPrimitive = JsonPrimitive::javaClass.New(env, constructor, number);
+        jni::DeleteLocalRef(env, boxedValue);
+        return jsonPrimitive;
+    }
+
+    /**
+     * Create a primitive containing a boolean value
+     */
+    jni::Object<JsonPrimitive> operator()(const bool value) const {
+        static auto constructor = JsonPrimitive::javaClass.GetConstructor<jni::Object<java::lang::Boolean>>(env);
+        auto boxedValue = java::lang::Boolean::valueOf(env, value);
+        auto jsonPrimitive = JsonPrimitive::javaClass.New(env, constructor, boxedValue);
+        jni::DeleteLocalRef(env, boxedValue);
+        return jsonPrimitive;
+    }
+};
+
+jni::Object<JsonPrimitive> JsonPrimitive::New(jni::JNIEnv &env, const value& value) {
+    JsonPrimitiveEvaluator evaluator { env };
+    return value::visit(value, evaluator);
+}
+
 JsonPrimitive::value JsonPrimitive::convert(jni::JNIEnv &env, jni::Object<JsonPrimitive> jsonPrimitive) {
     value value;
     if (jsonPrimitive) {
diff --git a/platform/android/src/gson/json_primitive.hpp b/platform/android/src/gson/json_primitive.hpp
index 5fc8a2b485..c418e0ebe8 100644
--- a/platform/android/src/gson/json_primitive.hpp
+++ b/platform/android/src/gson/json_primitive.hpp
@@ -15,6 +15,8 @@ public:
 
     static constexpr auto Name() { return "com/google/gson/JsonPrimitive"; };
 
+    static jni::Object<JsonPrimitive> New(jni::JNIEnv&, const value&);
+
     static value convert(JNIEnv&, jni::Object<JsonPrimitive>);
 
     static bool isBoolean(JNIEnv&, jni::Object<JsonPrimitive>);