Codereview request for JDK-8023669: MBean*Info.hashCode : NPE

[Daniel Fuchs]

On 8/29/13 9:34 AM, shanliang wrote:
> Hi,
>
> Please review following fix, it addresses the issue only in the method
> "hashCode":
>     bug: https://bugs.openjdk.java.net/browse/JDK-8023669
>     webrev: http://cr.openjdk.java.net/~sjiang/jdk-8023669/00/
>
> Thanks,
> Shanliang
>

Hi Shanliang,

<http://cr.openjdk.java.net/~sjiang/jdk-8023669/00/src/share/classes/javax/management/MBeanAttributeInfo.java.frames.html>

I suggest to simplify this by calling:

public int hashCode() {
    return Objects.hash(getName(), getType());
}

(see 
<http://docs.oracle.com/javase/7/docs/api/java/util/Objects.html#hash%28java.lang.Object...%29>)

<http://cr.openjdk.java.net/~sjiang/jdk-8023669/00/src/share/classes/javax/management/MBeanConstructorInfo.java.frames.html>

     int hash = getName() == null ? 10 : getName().hashCode();

could be replaced by:

     int hash = Objects.hashCode(getName());

Generally - and that stands for the other files you modified, you can
simplify things by replacing  x.hashCode() with Objects.hashCode(x)
whenever there's the possibility that x can be null.

Note however that Objects is an API @since JDK 7 - so if you intend
to backport this fix to 6 & 5 you will need to alter your changeset
when backporting it.


MBeanOperationInfo.java, MBeanParameterInfo.java: I suggest
to use Objects.hash(...);

best regards,

-- daniel

BTW: one more question: you're also testing toString() in the test
      and that's good - but are there any toString() that will require
      fixing?