Class ObjID
- java.lang.Object
-
- java.rmi.server.ObjID
- All Implemented Interfaces:
Serializable
public final class ObjID extends Object implements Serializable
An ObjID
is used to identify a remote object exported to an RMI runtime. When a remote object is exported, it is assigned an object identifier either implicitly or explicitly, depending on the API used to export.
The ObjID()
constructor can be used to generate a unique object identifier. Such an ObjID
is unique over time with respect to the host it is generated on. The ObjID(int)
constructor can be used to create a "well-known" object identifier. The scope of a well-known ObjID
depends on the RMI runtime it is exported to.
An ObjID
instance contains an object number (of type long
) and an address space identifier (of type UID
). In a unique ObjID
, the address space identifier is unique with respect to a given host over time. In a well-known ObjID
, the address space identifier is equivalent to one returned by invoking the UID(short)
constructor with the value zero.
If the system property java.rmi.server.randomIDs
is defined to equal the string "true"
(case insensitive), then the ObjID()
constructor will use a cryptographically strong random number generator to choose the object number of the returned ObjID
.
- Since:
- 1.1
- See Also:
- Serialized Form
Field Summary
Modifier and Type | Field | Description |
---|---|---|
static int | ACTIVATOR_ID | Object number for well-known |
static int | DGC_ID | Object number for well-known |
static int | REGISTRY_ID | Object number for well-known |
Constructor Summary
Constructor | Description |
---|---|
ObjID() | Generates a unique object identifier. |
ObjID(int objNum) | Creates a "well-known" object identifier. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
boolean | equals(Object obj) | Compares the specified object with this |
int | hashCode() | Returns the hash code value for this object identifier, the object number. |
static ObjID | read(ObjectInput in) | Constructs and returns a new |
String | toString() | Returns a string representation of this object identifier. |
void | write(ObjectOutput out) | Marshals a binary representation of this |
Methods declared in class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Field Detail
REGISTRY_ID
public static final int REGISTRY_ID
Object number for well-known ObjID
of the registry.
- See Also:
- Constant Field Values
ACTIVATOR_ID
public static final int ACTIVATOR_ID
Object number for well-known ObjID
of the activator.
- See Also:
- Constant Field Values
DGC_ID
public static final int DGC_ID
Object number for well-known ObjID
of the distributed garbage collector.
- See Also:
- Constant Field Values
Constructor Detail
ObjID
public ObjID()
Generates a unique object identifier.
If the system property java.rmi.server.randomIDs
is defined to equal the string "true"
(case insensitive), then this constructor will use a cryptographically strong random number generator to choose the object number of the returned ObjID
.
ObjID
public ObjID(int objNum)
Creates a "well-known" object identifier.
An ObjID
created via this constructor will not clash with any ObjID
s generated via the no-arg constructor.
- Parameters:
-
objNum
- object number for well-known object identifier
Method Detail
write
public void write(ObjectOutput out) throws IOException
Marshals a binary representation of this ObjID
to an ObjectOutput
instance.
Specifically, this method first invokes the given stream's DataOutput.writeLong(long)
method with this object identifier's object number, and then it writes its address space identifier by invoking its UID.write(DataOutput)
method with the stream.
- Parameters:
-
out
- theObjectOutput
instance to write thisObjID
to - Throws:
-
IOException
- if an I/O error occurs while performing this operation
read
public static ObjID read(ObjectInput in) throws IOException
Constructs and returns a new ObjID
instance by unmarshalling a binary representation from an ObjectInput
instance.
Specifically, this method first invokes the given stream's DataInput.readLong()
method to read an object number, then it invokes UID.read(DataInput)
with the stream to read an address space identifier, and then it creates and returns a new ObjID
instance that contains the object number and address space identifier that were read from the stream.
- Parameters:
-
in
- theObjectInput
instance to readObjID
from - Returns:
- unmarshalled
ObjID
instance - Throws:
-
IOException
- if an I/O error occurs while performing this operation
hashCode
public int hashCode()
Returns the hash code value for this object identifier, the object number.
- Overrides:
-
hashCode
in classObject
- Returns:
- the hash code value for this object identifier
- See Also:
-
Object.equals(java.lang.Object)
,System.identityHashCode(java.lang.Object)
equals
public boolean equals(Object obj)
Compares the specified object with this ObjID
for equality. This method returns true
if and only if the specified object is an ObjID
instance with the same object number and address space identifier as this one.
- Overrides:
-
equals
in classObject
- Parameters:
-
obj
- the object to compare thisObjID
to - Returns:
-
true
if the given object is equivalent to this one, andfalse
otherwise - See Also:
-
Object.hashCode()
,HashMap
toString
public String toString()
Returns a string representation of this object identifier.