How to create Java object in Unity3d (using AndroidJavaObject or AndroidJNI.NewObject)?

Question

What's the difference between creating the object using AndroidJavaObject and AndroidJNI.NewObject?

new AndroidJavaObject("android.content.Intent", ACTION_SEND);

vs

IntPtr intentClass = AndroidJNI.FindClass("android.content.Intent");
IntPtr intentConstructor = AndroidJNI.GetMethodID(IntentClass,"<init>","(Ljava/lang/String;)V");


jvalue[] intentParameters = new jvalue[1];
intentParameters[0] = ACTION_SEND;
IntPtr intentObject = AndroidJNI.NewObject(intentClass, intentConstructor, intentParameters);

Is AndroidJavaObject just a shorter version or there are any downsides?

Perhaps the AndroidJavaObject constructor always calls FindClass internally without any kind of caching. There are times where you might prefer just calling FindClass once and saving the result as a global reference for repeated use (e.g. trying to use FindClass for non-system classes on a purely native thread can be problematic). — Michael
– Michael, Commented Jul 20, 2018 at 9:14

Suvitruf - Andrei Apanasik · Accepted Answer · 2018-07-20 12:44:46Z

2

If you decompile this class, you will see that it does the same thing:

private void _AndroidJavaObject(string className, params object[] args)
{
  this.DebugPrint("Creating AndroidJavaObject from " + className);
  if (args == null)
    args = new object[1];
  using (AndroidJavaObject @class = AndroidJavaObject.FindClass(className))
  {
    this.m_jclass = new GlobalJavaObjectRef(@class.GetRawObject());
    jvalue[] jniArgArray = AndroidJNIHelper.CreateJNIArgArray(args);
    try
    {
      IntPtr num = AndroidJNISafe.NewObject((IntPtr) this.m_jclass, AndroidJNIHelper.GetConstructorID((IntPtr) this.m_jclass, args), jniArgArray);
      this.m_jobject = new GlobalJavaObjectRef(num);
      AndroidJNISafe.DeleteLocalRef(num);
    }
    finally
    {
      AndroidJNIHelper.DeleteJNIArgArray(args, jniArgArray);
    }
  }
}

edited Jul 20, 2018 at 12:44

answered Jul 20, 2018 at 9:21

Suvitruf - Andrei Apanasik

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