JAVADOC clarification needed in Class.getMethod

Kyung Koo Yoon yoonforh at
Sat Aug 29 13:40:53 UTC 2015

Hi, Jochen.

 Software Innovation Driver yoonforh at gmail dot com
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> 2015. 8. 29., 오후 10:01, Jochen Theodorou <blackdrag at> 작성:
> Am 29.08.2015 10:56, schrieb Kyung Koo Yoon:
>> Hi, all.
>> The javadoc comment of java.lang.Class.getMethod API has following clause.
>> @CallerSensitive
>>     public Method getMethod(String name, Class<?>... parameterTypes)
>>         throws NoSuchMethodException, SecurityException
>> "The {@code parameterTypes} parameter is an array of {@code Class}
>> objects that identify the method's formal parameter types, in declared
>>  order. If {@code parameterTypes} is {@code null}, it is
>>  treated as if it were an empty array."
>> As you know the method signature changed to use varargs since JDK 1.5,
>> if parameterTypes is given null, the compiler will interpret the parameter with “new Class[] { null }”.
> you are making a wrong assumption here. If null is given there will be
> no wrapping in an array.  varargs are defined that there is no wrapping
> if the given argument type is compatible. For Class[] this is Class[]
> and of course null. Even if you had been right, you could still give
> produce a call with null by reflection or using the MethodHandles API

You can check by simply decompiling the generated byte codes.
vararg is not a JVM feature so the compiler pre-processes and the compiler handles the given null as array’s first element.

Originally class.getMethod(“methodName”, null) should have meant a static method, but with vararg, it’s not.

> bye blackdrag
> -- 
> Jochen "blackdrag" Theodorou
> blog: <>

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