Allowing a Java object field to be null in a new JNI helper method.

webrtc/api/java/jni/jni_helpers.h

 /*
  *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 46 matching lines @@
     JNIEnv* jni, jclass c, const std::string& name, const char* signature);
 
 jmethodID GetStaticMethodID(
     JNIEnv* jni, jclass c, const char* name, const char* signature);
 
 jfieldID GetFieldID(JNIEnv* jni, jclass c, const char* name,
                     const char* signature);
 
 jclass GetObjectClass(JNIEnv* jni, jobject object);
 
+// Throws an exception if the object field is null.

[pthatcher1, 2016/04/11 19:39:29]

Doesn't the code actually crash?  

[Taylor Brandstetter, 2016/04/11 23:13:38]

Oh yeah. It calls abort(). I'll make a CL to fix this comment.

 jobject GetObjectField(JNIEnv* jni, jobject object, jfieldID id);

[pthatcher1, 2016/04/11 19:39:29]

Can we rename this one GetNonNullObjectField to make it clear things may throw
an exception (or crash)?

[Taylor Brandstetter, 2016/04/11 23:13:38]

Since you, Vlad and I prefer that naming, it seems worth doing. I'll do it in
the new CL.

 
+jobject GetNullableObjectField(JNIEnv* jni, jobject object, jfieldID id);
+
 jstring GetStringField(JNIEnv* jni, jobject object, jfieldID id);
 
 jlong GetLongField(JNIEnv* jni, jobject object, jfieldID id);
 
 jint GetIntField(JNIEnv* jni, jobject object, jfieldID id);
 
 bool GetBooleanField(JNIEnv* jni, jobject object, jfieldID id);
 
 // Returns true if |obj| == null in Java.
 bool IsNull(JNIEnv* jni, jobject obj);
@@ skipping 100 matching lines @@
  private:
   JNIEnv* jni_;
   jobject iterable_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(Iterable);
 };
 
 }  // namespace webrtc_jni
 
 #endif  // WEBRTC_API_JAVA_JNI_JNI_HELPERS_H_