* All you need to know: *
* UUID u = new UUID(); ** * @see * http://www.opengroup.org/onlinepubs/9629399/apdxa.htm * * @see * http://www.uddi.org/pubs/draft-leach-uuids-guids-01.txt * * @see UUID * @author Johann Burkard * @version $Id: UUID.java 1888 2009-03-15 12:43:24Z johann $ */ public class UUID implements Comparable
long values.
*
* @param time the upper 64 bits
* @param clockSeqAndNode the lower 64 bits
*/
public UUID(long time, long clockSeqAndNode) {
this.time = time;
this.clockSeqAndNode = clockSeqAndNode;
}
/**
* Copy constructor for UUID. Values of the given UUID are copied.
*
* @param u the UUID, may not be null
*/
public UUID(UUID u) {
this(u.time, u.clockSeqAndNode);
}
/**
* Parses a textual representation of a UUID.
*
* No validation is performed. If the {@link CharSequence} is shorter than 36 characters,
* {@link ArrayIndexOutOfBoundsException}s will be thrown.
*
* @param s the {@link CharSequence}, may not be null
*/
public UUID(CharSequence s) {
this(Hex.parseLong(s.subSequence(0, 18)), Hex.parseLong(s.subSequence(
19, 36)));
}
/**
* Compares this UUID to another Object. Throws a {@link ClassCastException} if
* the other Object is not an instance of the UUID class. Returns a value
* smaller than zero if the other UUID is "larger" than this UUID and a value
* larger than zero if the other UUID is "smaller" than this UUID.
*
* @param t the other UUID, may not be null
* @return a value < 0, 0 or a value > 0
* @see java.lang.Comparable#compareTo(java.lang.Object)
* @throws ClassCastException
*/
public int compareTo(UUID t) {
if (this == t) {
return 0;
}
if (time > t.time) {
return 1;
}
if (time < t.time) {
return -1;
}
if (clockSeqAndNode > t.clockSeqAndNode) {
return 1;
}
if (clockSeqAndNode < t.clockSeqAndNode) {
return -1;
}
return 0;
}
/**
* Tweaked Serialization routine.
*
* @param out the ObjectOutputStream
* @throws IOException
*/
private void writeObject(ObjectOutputStream out) throws IOException {
out.writeLong(time);
out.writeLong(clockSeqAndNode);
}
/**
* Tweaked Serialization routine.
*
* @param in the ObjectInputStream
* @throws IOException
*/
private void readObject(ObjectInputStream in) throws IOException {
time = in.readLong();
clockSeqAndNode = in.readLong();
}
/**
* Returns this UUID as a String.
*
* @return a String, never null
* @see java.lang.Object#toString()
* @see #toAppendable(Appendable)
*/
@Override
public final String toString() {
return toAppendable(null).toString();
}
/**
* Appends a String representation of this to the given {@link StringBuffer} or
* creates a new one if none is given.
*
* @param in the StringBuffer to append to, may be null
* @return a StringBuffer, never null
* @see #toAppendable(Appendable)
*/
public StringBuffer toStringBuffer(StringBuffer in) {
StringBuffer out = in;
if (out == null) {
out = new StringBuffer(36);
}
else {
out.ensureCapacity(out.length() + 36);
}
return (StringBuffer) toAppendable(out);
}
/**
* Appends a String representation of this object to the given {@link Appendable} object.
*
* For reasons I'll probably never understand, Sun has decided to have a number of I/O classes implement * Appendable which forced them to destroy an otherwise nice and simple interface with {@link IOException}s. *
* I decided to ignore any possible IOExceptions in this method.
*
* @param a the Appendable object, may be null
* @return an Appendable object, defaults to a {@link StringBuilder} if a is null
*/
public Appendable toAppendable(Appendable a) {
Appendable out = a;
if (out == null) {
out = new StringBuilder(36);
}
try {
Hex.append(out, (int) (time >> 32)).append('-');
Hex.append(out, (short) (time >> 16)).append('-');
Hex.append(out, (short) time).append('-');
Hex.append(out, (short) (clockSeqAndNode >> 48)).append('-');
Hex.append(out, clockSeqAndNode, 12);
}
catch (IOException ex) {
// What were they thinking?
}
return out;
}
/**
* Returns a hash code of this UUID. The hash code is calculated by XOR'ing the
* upper 32 bits of the time and clockSeqAndNode fields and the lower 32 bits of
* the time and clockSeqAndNode fields.
*
* @return an int representing the hash code
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
return (int) ((time >> 32) ^ time ^ (clockSeqAndNode >> 32) ^ clockSeqAndNode);
}
/**
* Clones this UUID.
*
* @return a new UUID with identical values, never null
*/
@Override
public Object clone() {
try {
return super.clone();
}
catch (CloneNotSupportedException ex) {
// One of Sun's most epic fails.
return null;
}
}
/**
* Returns the time field of the UUID (upper 64 bits).
*
* @return the time field
*/
public final long getTime() {
return time;
}
/**
* Returns the clock and node field of the UUID (lower 64 bits).
*
* @return the clockSeqAndNode field
*/
public final long getClockSeqAndNode() {
return clockSeqAndNode;
}
/**
* Compares two Objects for equality.
*
* @see java.lang.Object#equals(Object)
* @param obj the Object to compare this UUID with, may be null
* @return true if the other Object is equal to this UUID,
* false if not
*/
@Override
public boolean equals(Object obj) {
if (!(obj instanceof UUID)) {
return false;
}
return compareTo((UUID) obj) == 0;
}
/**
* Returns the nil UUID (a UUID whose values are both set to zero).
*
* Starting with version 2.0, this method does return a new UUID instance every
* time it is called. Earlier versions returned one instance. This has now been
* changed because this UUID has public, non-final instance fields. Returning a
* new instance is therefore more safe.
*
* @return a nil UUID, never null
*/
public static UUID nilUUID() {
return new UUID(0, 0);
}
}