<s>
A	O
phantom	B-General_Concept
reference	I-General_Concept
is	O
a	O
kind	O
of	O
reference	O
in	O
Java	B-Language
,	O
where	O
the	O
memory	O
can	O
be	O
reclaimed	O
.	O
</s>
<s>
The	O
phantom	B-General_Concept
reference	I-General_Concept
is	O
one	O
of	O
the	O
strengths	O
or	O
levels	O
of	O
'	O
non	O
strong	B-General_Concept
 '	O
reference	O
defined	O
in	O
the	O
Java	B-Language
programming	I-Language
language	I-Language
;	O
the	O
others	O
being	O
weak	B-General_Concept
and	O
soft	B-General_Concept
.	O
</s>
<s>
Phantom	B-General_Concept
reference	I-General_Concept
are	O
the	O
weakest	O
level	O
of	O
reference	O
in	O
Java	B-Language
;	O
in	O
order	O
from	O
strongest	O
to	O
weakest	O
,	O
they	O
are	O
:	O
strong	B-General_Concept
,	O
soft	B-General_Concept
,	O
weak	B-General_Concept
,	O
phantom	O
.	O
</s>
<s>
An	O
object	O
is	O
phantomly	O
referenced	O
after	O
it	O
has	O
been	O
finalized	B-Application
.	O
</s>
<s>
In	O
Java	B-Language
8	O
and	O
earlier	O
versions	O
,	O
the	O
reference	O
needs	O
to	O
be	O
cleared	O
before	O
the	O
memory	O
for	O
a	O
finalized	B-Application
referent	O
can	O
be	O
reclaimed	O
.	O
</s>
<s>
A	O
change	O
in	O
Java	B-Language
9	O
will	O
allow	O
memory	O
from	O
a	O
finalized	B-Application
referent	O
to	O
be	O
reclaimable	O
immediately	O
.	O
</s>
<s>
Phantom	B-General_Concept
references	I-General_Concept
are	O
of	O
limited	O
use	O
,	O
primarily	O
narrow	O
technical	O
uses	O
.	O
</s>
