[android] geojson conversion optimisation

platform/android/src/geojson/multi_line_string.cpp

@@ -0,0 +1,56 @@
+#include "multi_line_string.hpp"
+
+#include "line_string.hpp"
+
+namespace mbgl {
+namespace android {
+namespace geojson {
+
+mapbox::geojson::multi_line_string MultiLineString::convert(jni::JNIEnv &env, jni::Object<MultiLineString> jMultiLineString) {
+    mapbox::geojson::multi_line_string multiLineString;
+
+    if (jMultiLineString) {
+        auto jPositionListsList = MultiLineString::getCoordinates(env, jMultiLineString);
+        multiLineString = MultiLineString::convert(env, jPositionListsList);
+        jni::DeleteLocalRef(env, jPositionListsList);
+    }
+
+    return multiLineString;
+}
+
+mapbox::geojson::multi_line_string MultiLineString::convert(jni::JNIEnv &env, jni::Object<java::util::List/*<java::util::List<Position>>*/> jPositionListsList) {
+    mapbox::geojson::multi_line_string multiLineString;
+
+    if (jPositionListsList) {
+        auto jPositionListsArray = java::util::List::toArray<java::util::List>(env, jPositionListsList);
+
+        auto size = jPositionListsArray.Length(env);
+        multiLineString.reserve(size);
+
+        for (std::size_t i = 0; i < size; i++) {
+            auto jPositionList = jPositionListsArray.Get(env, i);
+            multiLineString.push_back(LineString::convert(env, jPositionList));
+            jni::DeleteLocalRef(env, jPositionList);
+        }
+
+        jni::DeleteLocalRef(env, jPositionListsArray);
+    }
+
+    return multiLineString;
+}
+
+jni::Object<java::util::List> MultiLineString::getCoordinates(jni::JNIEnv &env, jni::Object<MultiLineString> jLineString) {
+    static auto method = MultiLineString::javaClass.GetMethod<jni::Object<java::util::List> ()>(env, "getCoordinates");
+    return jLineString.Call(env, method);
+}
+
+void MultiLineString::registerNative(jni::JNIEnv &env) {
+    // Lookup the class
+    javaClass = *jni::Class<MultiLineString>::Find(env).NewGlobalRef(env).release();
+}
+
+jni::Class<MultiLineString> MultiLineString::javaClass;
+
+} // namespace geojson
+} // namespace android
+} // namespace mbgl