Direct-BT: API doc and clarify interface JavaAnonObj, JavaUplink and JavaAnonObj implementation JavaGlobalObj

JavaAnonObj is now a full virtual interface.
JavaGlobalObj gets default spec for copy and move ctor and assignment.

2 files changed, 22 insertions, 2 deletions

diff --git a/api/direct_bt/JavaUplink.hpp b/api/direct_bt/JavaUplink.hpp
index bea38e4..601bafd 100644
--- a/api/direct_bt/JavaUplink.hpp
+++ b/api/direct_bt/JavaUplink.hpp
@@ -33,15 +33,27 @@ namespace direct_bt {
 
     #define JAVA_DBT_PACKAGE "direct_bt/tinyb/"
 
+    /**
+     * Pure virtual JavaAnonObj, hiding Java JNI details from API,
+     * to be implemented by JNI module.
+     * <p>
+     * One implementation is JavaGlobalObj within the JNI module,
+     * wrapping a JNIGlobalRef instance.
+     * </p>
+     */
     class JavaAnonObj {
         public:
             virtual ~JavaAnonObj() { }
             virtual std::string toString() const { return "JavaAnonObj[???]"; }
 
             /** Clears the java reference, i.e. nulling it, without deleting the global reference via JNI. */
-            virtual void clear() { }
+            virtual void clear() = 0;
     };
 
+    /**
+     * Sharing the anonymous Java object (JavaAnonObj),
+     * i.e. exposing the Java object uplink to the C++ implementation.
+     */
     class JavaUplink {
         private:
             std::shared_ptr<JavaAnonObj> javaObjectRef;
diff --git a/java/jni/direct_bt/helper_dbt.hpp b/java/jni/direct_bt/helper_dbt.hpp
index b2f002d..40e2c60 100644
--- a/java/jni/direct_bt/helper_dbt.hpp
+++ b/java/jni/direct_bt/helper_dbt.hpp
@@ -52,6 +52,10 @@ namespace direct_bt {
     };
     extern DirectBTJNISettings directBTJNISettings;
 
+    /**
+     * Implementation for JavaAnonObj,
+     * by simply wrapping a JNIGlobalRef instance.
+     */
     class JavaGlobalObj : public JavaAnonObj {
         private:
             JNIGlobalRef javaObjectRef;
@@ -77,7 +81,11 @@ namespace direct_bt {
                 return true;
             }
             JavaGlobalObj(jobject obj) : javaObjectRef(obj) { }
-            ~JavaGlobalObj() override { }
+
+            JavaGlobalObj(const JavaGlobalObj &o) noexcept = default;
+            JavaGlobalObj(JavaGlobalObj &&o) noexcept = default;
+            JavaGlobalObj& operator=(const JavaGlobalObj &o) noexcept = default;
+            JavaGlobalObj& operator=(JavaGlobalObj &&o) noexcept = default;
 
             std::string toString() const override {
                 const uint64_t ref = (uint64_t)(void*)javaObjectRef.getObject();