java.lang.Object | |
↳ | java.rmi.server.UID |
A UID
represents an identifier that is unique over time
with respect to the host it is generated on, or one of 216
"well-known" identifiers.
The UID()
constructor can be used to generate an
identifier that is unique over time with respect to the host it is
generated on. The UID(short)
constructor can be used to
create one of 216 well-known identifiers.
A UID
instance contains three primitive values:
unique
, an int
that uniquely identifies
the VM that this UID
was generated in, with respect to its
host and at the time represented by the time
value (an
example implementation of the unique
value would be a
process identifier),
or zero for a well-known UID
time
, a long
equal to a time (as returned
by currentTimeMillis()
) at which the VM that this
UID
was generated in was alive,
or zero for a well-known UID
count
, a short
to distinguish
UID
s generated in the same VM with the same
time
value
An independently generated UID
instance is unique
over time with respect to the host it is generated on as long as
the host requires more than one millisecond to reboot and its system
clock is never set backward. A globally unique identifier can be
constructed by pairing a UID
instance with a unique host
identifier, such as an IP address.
Public Constructors | |||||||||||
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Generates a
UID that is unique over time with
respect to the host that it was generated on. | |||||||||||
Creates a "well-known"
UID . |
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Compares the specified object with this
UID for
equality. | |||||||||||
Returns the hash code value for this
UID . | |||||||||||
Constructs and returns a new
UID instance by
unmarshalling a binary representation from an
DataInput instance. | |||||||||||
Returns a string representation of this
UID . | |||||||||||
Marshals a binary representation of this
UID to
a DataOutput instance. |
[Expand]
Inherited Methods | |||||||||||
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From class
java.lang.Object
|
Generates a UID
that is unique over time with
respect to the host that it was generated on.
Creates a "well-known" UID
.
There are 216 possible such well-known ids.
A UID
created via this constructor will not
clash with any UID
s generated via the no-arg
constructor.
num | number for well-known UID
|
---|
Compares the specified object with this UID
for
equality.
This method returns true
if and only if the
specified object is a UID
instance with the same
unique
, time
, and count
values as this one.
obj | the object to compare this UID to |
---|
true
if the given object is equivalent to
this one, and false
otherwise
Returns the hash code value for this UID
.
UID
Constructs and returns a new UID
instance by
unmarshalling a binary representation from an
DataInput
instance.
Specifically, this method first invokes the given stream's
readInt()
method to read a unique
value,
then it invoke's the stream's
readLong()
method to read a time
value,
then it invoke's the stream's
readShort()
method to read a count
value,
and then it creates and returns a new UID
instance
that contains the unique
, time
, and
count
values that were read from the stream.
in | the DataInput instance to read
UID from |
---|
UID
instanceIOException | if an I/O error occurs while performing this operation |
---|
Returns a string representation of this UID
.
UID
Marshals a binary representation of this UID
to
a DataOutput
instance.
Specifically, this method first invokes the given stream's
writeInt(int)
method with this UID
's
unique
value, then it invokes the stream's
writeLong(long)
method with this UID
's
time
value, and then it invokes the stream's
writeShort(int)
method with this UID
's
count
value.
out | the DataOutput instance to write
this UID to |
---|
IOException | if an I/O error occurs while performing this operation |
---|