1 files changed, 115 insertions, 0 deletions
diff --git a/java/jni/helper.cxx b/java/jni/helper.cxx
new file mode 100644
index 00000000..9f41eea3
--- /dev/null
+++ b/java/jni/helper.cxx
@@ -0,0 +1,115 @@
+#include <jni.h>
+#include <memory>
+#include <stdexcept>
+#include <vector>
+
+#include "helper.h"
+
+jfieldID getInstanceField(JNIEnv *env, jobject obj)
+{
+    jclass clazz = env->GetObjectClass(obj);
+    // J == long
+    return env->GetFieldID(clazz, "nativeInstance", "J");
+}
+
+jclass search_class(JNIEnv *env, const char *clazz_name)
+{
+    jclass clazz = env->FindClass(clazz_name);
+    if (clazz == NULL)
+    {
+        throw std::runtime_error("no class found\n");
+    }
+    return clazz;
+}
+
+jmethodID search_method(JNIEnv *env, jclass clazz, const char *method_name,
+                const char *prototype, bool is_static)
+{
+    jmethodID method;
+    if(is_static)
+    {
+        method = env->GetStaticMethodID(clazz, method_name, prototype);
+    }
+    else
+    {
+        method = env->GetMethodID(clazz, method_name, prototype);
+    }
+
+    if(method == NULL)
+    {
+        throw std::runtime_error("no method found\n");
+    }
+
+    return method;
+}
+
+jfieldID search_field(JNIEnv *env, jclass clazz, const char *field_name,
+                const char *type, bool is_static)
+{
+    jfieldID field;
+    if(is_static)
+    {
+        field = env->GetStaticFieldID(clazz, field_name, type);
+    }
+    else
+    {
+        field = env->GetFieldID(clazz, field_name, type);
+    }
+
+    if(field == NULL)
+    {
+        throw std::runtime_error("no method found\n");
+    }
+
+    return field;
+}
+
+bool from_jboolean_to_bool(jboolean val)
+{
+    bool result;
+
+    if (val == JNI_TRUE)
+    {
+        result = true;
+    }
+    else
+    {
+        if (val == JNI_FALSE)
+        {
+            result = false;
+        }
+        else
+        {
+            throw std::invalid_argument("the jboolean value is not true/false\n");
+        }
+    }
+
+    return result;
+}
+
+jobject get_bluetooth_type(JNIEnv *env, const char *field_name)
+{
+    jclass b_type_enum = search_class(env, "BluetoothType");
+
+    jfieldID b_type_field = search_field(env, b_type_enum, field_name, "l", true);
+
+    jobject result = env->GetStaticObjectField(b_type_enum, b_type_field);
+    return result;
+}
+
+
+jobject get_new_arraylist(JNIEnv *env, unsigned int size, jmethodID *add)
+{
+    jclass arraylist_class = search_class(env, "Ljava/util/ArrayList;");
+    jmethodID arraylist_ctor = search_method(env, arraylist_class, "<init>", "(I)V", false);
+
+    jobject result = env->NewObject(arraylist_class, arraylist_ctor, size);
+    if (result == NULL)
+    {
+        throw std::runtime_error("cannot create instance of class\n");
+    }
+
+    *add = search_method(env, arraylist_class, "add", "(Ljava/lang/Object;)Z", false);
+
+    return result;
+}