--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Plugin/JavaLocalObject.cpp	Thu Oct 19 11:14:45 2023 +0200
@@ -0,0 +1,107 @@
+/**
+ * SPDX-FileCopyrightText: 2023 Sebastien Jodogne, UCLouvain, Belgium
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/**
+ * Java plugin for Orthanc
+ * Copyright (C) 2023 Sebastien Jodogne, UCLouvain, Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#include "JavaLocalObject.h"
+
+#include <memory>
+#include <stdexcept>
+
+
+JavaLocalObject::JavaLocalObject(JavaEnvironment& env,
+                                 jobject obj,
+                                 bool objCanBeNull) :
+  env_(&env.GetValue()),
+  obj_(obj)
+{
+  if (!objCanBeNull && obj == NULL)
+  {
+    throw std::runtime_error("Null pointer");
+  }
+}
+
+
+JavaLocalObject::~JavaLocalObject()
+{
+  env_->DeleteLocalRef(obj_);
+}
+
+
+JavaLocalObject* JavaLocalObject::CreateArrayOfStrings(JavaEnvironment& env,
+                                                       const std::vector<std::string>& items)
+{
+  JavaLocalObject emptyString(env, env.GetValue().NewStringUTF(""));
+
+  jobjectArray obj = env.GetValue().NewObjectArray(
+    items.size(), env.GetValue().FindClass("java/lang/String"),
+    emptyString.GetValue());
+
+  if (obj == NULL)
+  {
+    throw std::runtime_error("Cannot create an array of Java strings");
+  }
+  else
+  {
+    std::unique_ptr<JavaLocalObject> result(new JavaLocalObject(env, obj));
+
+    for (size_t i = 0; i < items.size(); i++)
+    {
+      JavaLocalObject item(env, env.GetValue().NewStringUTF(items[i].c_str()));
+      env.GetValue().SetObjectArrayElement(obj, i, item.GetValue());
+    }
+
+    return result.release();
+  }
+}
+
+
+JavaLocalObject* JavaLocalObject::CreateDictionary(JavaEnvironment& env,
+                                                   const std::map<std::string, std::string>& items)
+{
+  // NB: In JNI, there are no generics. All the templated arguments
+  // are taken as instances of the "Object" base class.
+
+  jclass cls = env.FindClass("java/util/HashMap");
+  jmethodID constructor = env.GetMethodID(cls, "<init>", "()V");
+  jmethodID setter = env.GetMethodID(cls, "put", "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;");
+  jobject obj = env.GetValue().NewObject(cls, constructor);
+
+  if (obj == NULL)
+  {
+    throw std::runtime_error("Cannot create a Java dictionary");
+  }
+  else
+  {
+    std::unique_ptr<JavaLocalObject> result(new JavaLocalObject(env, obj));
+
+    for (std::map<std::string, std::string>::const_iterator it = items.begin(); it != items.end(); ++it)
+    {
+      JavaLocalObject key(env, env.GetValue().NewStringUTF(it->first.c_str()));
+      JavaLocalObject value(env, env.GetValue().NewStringUTF(it->second.c_str()));
+      JavaLocalObject previousValue(env, env.GetValue().CallObjectMethod(obj, setter, key.GetValue(), value.GetValue()), true);
+      env.CheckException();
+    }
+
+    return result.release();
+  }
+}