sc.util

Class UniqueIdentifier

java.lang.Object

sc.util.UniqueIdentifier

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable

Direct Known Subclasses:

RequestId

public abstract class UniqueIdentifier
extends java.lang.Object
implements java.io.Externalizable

An abstract identifier class for re-use in very quickly generating and passing (between processes) fairly unique ids. The identifiers generated are not absolutely guaranteed to be globally unique, but should be sufficiently unique for most practical purposes. This class also places some emphasis on providing, but not guaranteeing, some logical meaning (e.g. constantly increasing numeric fields within a generating classloader, common fields for a given host and classloader, etc) in the identifiers' string form. Subclasses can add more fields for uniqueness and/or meaning as necessary.

Although this class is designed to be sub-classed other classes should generally not rely upon these subclasses being subclasses of this class. This class is generally a private implementation artifact that just happens to be designed for re-use via subclassing rather than aggregation (mainly to keep the number of objects allocated down to just one).

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static char	SEPARATOR_CHAR Character used to separate fields in string representation.

Constructor Summary

Constructors

Constructor and Description
UniqueIdentifier() Default constructor; no intialization is done here.
UniqueIdentifier(java.lang.String stringRep) Construct instance from string representation as per parseBaseFields().

Method Summary

Modifier and Type	Method and Description
void	appendTo(java.lang.StringBuilder builder) Append string representation to the given StringBuilder.
boolean	equals(java.lang.Object object) Overridden to quickly examine all internal fields for logical equality.
long	getIdNumber() Return internal sequence id number.
int	hashCode() Overriden to efficiently generate hash codes from the most unique internal field(s).
void	readExternal(java.io.ObjectInput in) Method implementation required by Externalizable interface
java.lang.String	toString() Produce string representation.
void	writeExternal(java.io.ObjectOutput out) Method implementation required by Externalizable interface

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Field Detail

SEPARATOR_CHAR

public static final char SEPARATOR_CHAR

Character used to separate fields in string representation. Generally, this should not be of interest to other classes, but in some specialized cases it is so we expose it here.

See Also:

Constant Field Values

Constructor Detail

UniqueIdentifier

public UniqueIdentifier()

Default constructor; no intialization is done here.

UniqueIdentifier

public UniqueIdentifier(java.lang.String stringRep)

Construct instance from string representation as per parseBaseFields().

Method Detail

toString

public java.lang.String toString()

Produce string representation.

Overrides:

toString in class java.lang.Object

appendTo

public void appendTo(java.lang.StringBuilder builder)

Append string representation to the given StringBuilder.

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Method implementation required by Externalizable interface

Specified by:

writeExternal in interface java.io.Externalizable

Throws:

java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Method implementation required by Externalizable interface

Specified by:

readExternal in interface java.io.Externalizable

Throws:

java.io.IOException

java.lang.ClassNotFoundException

hashCode

public int hashCode()

Overriden to efficiently generate hash codes from the most unique internal field(s). This method should generally not need to be overriden by subclasses.

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object object)

Overridden to quickly examine all internal fields for logical equality.

Overrides:

equals in class java.lang.Object

getIdNumber

public long getIdNumber()

Return internal sequence id number. This constantly increases over time within a instance of this class. This method exists primarily for specialized internal use cases and should generally not be used.