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// Copyright (c) 2011 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_SCOPED_JAVA_REFERENCE_H_
#define BASE_ANDROID_SCOPED_JAVA_REFERENCE_H_
#include <jni.h>
#include <stddef.h>
namespace base {
namespace android {
// Holds a local reference to a Java object. The local reference is scoped
// to the lifetime of this object. Note that since a JNI Env is only suitable
// for use on a single thread, objects of this class must be created, used and
// destroyed on the same thread.
template<typename T>
class ScopedJavaReference {
public:
// Holds a NULL reference.
ScopedJavaReference()
: env_(NULL),
obj_(NULL) {
}
// Assumes that obj is a local reference to a Java object and takes ownership
// of this local reference.
ScopedJavaReference(JNIEnv* env, T obj)
: env_(env),
obj_(obj) {
}
// Takes a new local reference to the Java object held by other.
ScopedJavaReference(const ScopedJavaReference& other)
: env_(other.env_),
obj_(other.obj_ ? static_cast<T>(other.env_->NewLocalRef(other.obj_)) :
NULL) {
}
~ScopedJavaReference() {
if (obj_)
env_->DeleteLocalRef(obj_);
}
void operator=(const ScopedJavaReference& other) {
if (obj_)
env_->DeleteLocalRef(obj_);
env_ = other.env_;
obj_ = other.obj_ ? static_cast<T>(env_->NewLocalRef(other.obj_)) : NULL;
}
JNIEnv* env() const { return env_; }
T obj() const { return obj_; }
// Releases the local reference to the caller. The caller *must* delete the
// local reference when it is done with it.
T Release() {
jobject obj = obj_;
obj_ = NULL;
return obj;
}
private:
JNIEnv* env_;
T obj_;
};
} // namespace android
} // namespace base
#endif // BASE_ANDROID_SCOPED_JAVA_REFERENCE_H_
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