Useless null check in HashMap.merge()

[Zheka Kozlov]

Oh yes, you are right. Then this is not dead code, just a useless null
check.

2018-07-04 19:55 GMT+07:00 Scott Palmer <swpalmer at gmail.com>:

> On Jul 4, 2018, at 5:42 AM, Zheka Kozlov <orionllmain at gmail.com> wrote:
> >
> > I noticed dead code in java.util.HashMap.merge():
> >
> > public V merge(K key, V value,
> >                   BiFunction<? super V, ? super V, ? extends V>
> > remappingFunction) {
> >    if (value == null)
> >        throw new NullPointerException();
> >
> >    ...
> >
> >    if (value != null) { *// Condition ' value != null' is always true*
> >        if (t != null)
> >            t.putTreeVal(this, tab, hash, key, value);
> >        else {
> >            tab[i] = newNode(hash, key, value, first);
> >            if (binCount >= TREEIFY_THRESHOLD - 1)
> >                treeifyBin(tab, hash);
> >        }
> >        ++modCount;
> >        ++size;
> >        afterNodeInsertion(true);
> >    }
> >    return value;
> > }
> >
> > The code in the if branch will never be executed because `value` was
> > previously checked at the beginning of the method.
> >
> > Is this a mistake?
>
> You mean it will ALWAYS be executed.  Yes, it looks to me like the ‘if’ is
> useless.
>
>
>