RAII JNI string

jni_string.hpp

#include <jni.h>

class jni_string 
{
public:
    jni_string (JNIEnv *env, 
                jstring javaString)
        : _env(env)
        , _javaString(javaString)
    { 
        _nativeString = _env->GetStringUTFChars(_javaString, 0); 
    }

    ~jni_string ()
    {
        if (_nativeString)
        {
            _env->ReleaseStringUTFChars(_javaString, _nativeString);
        }
    }
    
    jni_string (jni_string && other)
        : _env(std::move(other._env))
        , _javaString(std::move(other._javaString))
        , _nativeString(std::move(other._nativeString))
    {
        other._nativeString = nullptr;        
    }
    
    jni_string &
    operator= (jni_string && other)
    {
        if (&other != this)
        {
            _env          = std::move(other._env);
            _javaString   = std::move(other._javaString);
            _nativeString = std::move(other._nativeString);

            other._nativeString = nullptr;
        }
        return *this;
    }

    operator const char *() const { return _nativeString; }
    
    const char * const c_str () const { return _nativeString; }
    
private:
    jni_string (const jni_string &x) = delete;
    jni_string &operator=(const jni_string &x) = delete;
    
private:
    JNIEnv     * _env;
    jstring      _javaString;
    const char * _nativeString;
};