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javatools.util
Class JQueue  

java.lang.Object
  javatools.util.JQueue

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public class JQueue

extends java.lang.Object

Implements a regular queue. The only unusual thing is you can delete things from the middle of the queue efficiently by supplying the QueueKey which is returned by put(). In terms of implementation we use a Dictionary Hashtable instead of a perhaps more traditional vector with round-robin pointers. The benefit here is efficient implementation of the remove functionality. It also happens to be a really easy way to implement queues in general. The way it works is that the dictionary is used as a sparse array. The upper and lower bounds of the sparse array keeping growing up and up towards infinity. This is ok because the key is a long and will take several million years of running before any problems arise.

Version:

0.7

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Nested Class Summary
class	JQueue.QueueKey           A class which can be used to pass to remove to remove something from the middle of the queue.

 

Field Summary
private  long	get           The next "get" position
private  java.util.Dictionary	hash           We store the queue here
private  long	put           The next "put" position.

 

Constructor Summary

JQueue()           Creates a new empty JQueue.

JQueue(int size)           Constructor which takes an initial guesstimate of how many items we expect to store in it

 

Method Summary
void	clear()
boolean	empty()           Is the queue empty?
java.lang.Object	get()           Pull something out of the end of the queue and remove it from the queue.
private  void	init(int size)           Setup initialization
java.lang.Object	peek()           Get something out of the queue without removing it.
JQueue.QueueKey	put(java.lang.Object o)           Push something onto the queue
java.lang.Object	remove(JQueue.QueueKey key)           Remove an item from anywhere in the queue.
int	size()           Returns the number of elements in the queue

 

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Field Detail

hash

private java.util.Dictionary hash

We store the queue here

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put

private long put

The next "put" position.

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get

private long get

The next "get" position

Constructor Detail

JQueue

public JQueue(int size)

Constructor which takes an initial guesstimate of how many items we expect to store in it

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JQueue

public JQueue()

Creates a new empty JQueue.

Method Detail

get

public java.lang.Object get()

Pull something out of the end of the queue and remove it from the queue.

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size

public int size()

Returns the number of elements in the queue

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remove

public java.lang.Object remove(JQueue.QueueKey key)

Remove an item from anywhere in the queue.

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clear

public void clear()

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put

public JQueue.QueueKey put(java.lang.Object o)

Push something onto the queue

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empty

public boolean empty()

Is the queue empty?

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peek

public java.lang.Object peek()

Get something out of the queue without removing it.

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init

private void init(int size)

Setup initialization

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