[Android] Java Bridge with Gin: implement Java methods invocation

base/android/jni_weak_ref.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_ANDROID_JNI_WEAK_REF_H_
 #define BASE_ANDROID_JNI_WEAK_REF_H_
 
 #include <jni.h>
 
 #include "base/android/scoped_java_ref.h"
 #include "base/base_export.h"
 
 // Manages WeakGlobalRef lifecycle.
 // This class is not thread-safe w.r.t. get() and reset(). Multiple threads may
 // safely use get() concurrently, but if the user calls reset() (or of course,
 // calls the destructor) they'll need to provide their own synchronization.
 class BASE_EXPORT JavaObjectWeakGlobalRef {
  public:
   JavaObjectWeakGlobalRef();
   JavaObjectWeakGlobalRef(const JavaObjectWeakGlobalRef& orig);
   JavaObjectWeakGlobalRef(JNIEnv* env, jobject obj);
   virtual ~JavaObjectWeakGlobalRef();
 
   void operator=(const JavaObjectWeakGlobalRef& rhs);
 
   base::android::ScopedJavaLocalRef<jobject> get(JNIEnv* env) const;
 
+  bool is_null() const { return obj_ == NULL; }

[bulach, 2014/06/09 11:44:33]

hmm... :)

this can be misleading, it'd be possible to is_null() == false, and yet, get()
can return a "real object" that can be NULL...

how about "is_initialized()", or "has_reference()" ?

[mnaganov (inactive), 2014/06/11 13:50:44]

Thanks for raising this! Indeed, is_null() seems to be misleading.

My preference will be is_empty() -- also looks informative(and is similar to the
terminology used in variant types) and is short.

+
   void reset();
 
  private:
   void Assign(const JavaObjectWeakGlobalRef& rhs);
 
   jweak obj_;
 };
 
 // Get the real object stored in the weak reference returned as a
 // ScopedJavaLocalRef.
 BASE_EXPORT base::android::ScopedJavaLocalRef<jobject> GetRealObject(
     JNIEnv* env, jweak obj);
 
 #endif  // BASE_ANDROID_JNI_WEAK_REF_H_