File	Doc	Category	Size	Date	Package
UID.java	API Doc	Java SE 5 API	8164	Fri Aug 26 14:57:14 BST 2005	java.rmi.server

UID

• java.lang.Object

Fields Summary
private static final long	ONE_SECOND
private static int	hostUnique
private static boolean	hostUniqueSet
private static final Object	lock
private static long	lastTime
private static short	lastCount
private static final long	serialVersionUID indicate compatibility with JDK 1.1.x version of class
private final int	unique number that uniquely identifies the VM that this UID was generated in with respect to its host and at the given time
private final long	time a time (as returned by {@link System#currentTimeMillis()}) at which the VM that this UID was generated in was alive
private final short	count 16-bit number to distinguish UID instances created in the same VM with the same time value

Constructors Summary
public UID() Generates a UID that is unique over time with respect to the host that it was generated on. synchronized (lock) { if (!hostUniqueSet) { hostUnique = (new SecureRandom()).nextInt(); hostUniqueSet = true; } unique = hostUnique; if (lastCount == Short.MAX_VALUE) { boolean done = false; while (!done) { long now = System.currentTimeMillis(); if (now < lastTime + ONE_SECOND) { // pause for a second to wait for time to change try { Thread.currentThread().sleep(ONE_SECOND); } catch (java.lang.InterruptedException e) { } // ignore exception continue; } else { lastTime = now; lastCount = Short.MIN_VALUE; done = true; } } } time = lastTime; count = lastCount++; }
public UID(short num) Creates a "well-known" UID. There are 216 possible such well-known ids. A UID created via this constructor will not clash with any UIDs generated via the no-arg constructor. param num number for well-known UID unique = 0; time = 0; count = num;
private UID(int unique, long time, short count) Constructs a UID given data read from a stream. this.unique = unique; this.time = time; this.count = count;

Methods Summary
public boolean	equals(java.lang.Object obj) 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. param obj the object to compare this UID to return true if the given object is equivalent to this one, and false otherwise if (obj instanceof UID) { UID uid = (UID)obj; return (unique == uid.unique && count == uid.count && time == uid.time); } else { return false; }
public int	hashCode() Returns the hash code value for this UID. return the hash code value for this UID return (int) time + (int) count;
public static java.rmi.server.UID	read(java.io.DataInput in) 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 {@link DataInput#readInt()} method to read a unique value, then it invoke's the stream's {@link DataInput#readLong()} method to read a time value, then it invoke's the stream's {@link DataInput#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. param in the DataInput instance to read UID from return unmarshalled UID instance throws IOException if an I/O error occurs while performing this operation int unique = in.readInt(); long time = in.readLong(); short count = in.readShort(); return new UID(unique, time, count);
public java.lang.String	toString() Returns a string representation of this UID. return a string representation of this UID return Integer.toString(unique,16) + ":" + Long.toString(time,16) + ":" + Integer.toString(count,16);
public void	write(java.io.DataOutput out) Marshals a binary representation of this UID to a DataOutput instance. Specifically, this method first invokes the given stream's {@link DataOutput#writeInt(int)} method with this UID's unique value, then it invokes the stream's {@link DataOutput#writeLong(long)} method with this UID's time value, and then it invokes the stream's {@link DataOutput#writeShort(int)} method with this UID's count value. param out the DataOutput instance to write this UID to throws IOException if an I/O error occurs while performing this operation out.writeInt(unique); out.writeLong(time); out.writeShort(count);