org.metasyntactic.utilities
Class Odometer

java.lang.Object
  |
  +--org.metasyntactic.utilities.Odometer

All Implemented Interfaces:

java.util.Iterator

public class Odometer

extends java.lang.Object

implements java.util.Iterator

This class enumerates all values of an odometer for you. The values are returned to you as an int[]. In the zeroth place of the array is the most significant digit.

The class also can act as a permutation generator. The permutations are returned in lexicographic order. For example, if you want to generate all the 3-permutations of the numbers 0-3:

		Odometer o = new Odometer(3, 4, true);

	   while (o.hasMoreElements()) {
		   System.out.println(ArrayUtilities.toString(o.nextElement()));
	   }
 produces:
	  {0, 1, 2}
	  {0, 1, 3}
	  {0, 2, 1}
	  {0, 2, 3}
	  {0, 3, 1}
	  {0, 3, 2}
	  {1, 0, 2}
	  {1, 0, 3}
	  {1, 2, 0}
	  {1, 2, 3}
	  {1, 3, 0}
	  {1, 3, 2}
	  {2, 0, 1}
	  {2, 0, 3}
	  {2, 1, 0}
	  {2, 1, 3}
	  {2, 3, 0}
	  {2, 3, 1}
	  {3, 0, 1}
	  {3, 0, 2}
 

Field Summary

protected int[]	odometer The current states of the odometer.
protected boolean	ongoing We are done when we have generated the last valid odometer setting before a complete rollover
protected boolean	permute Are we generating only valid permutations? Or are we a normal odometer?
protected int	rollover The digit to rollover on.

Constructor Summary

Odometer(int digits, int rollover)
Constructs a normal (non-permuting) odometer.

Odometer(int digits, int rollover, boolean permute)

Method Summary

boolean	hasNext()
static void	main(java.lang.String[] args)
java.lang.Object	next()
int[]	nextPosition()
void	remove()

Methods inherited from class java.lang.Object

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

Field Detail

odometer

protected final int[] odometer

The current states of the odometer. A copy of this will be returned on every call to 'nextElement'

rollover

protected final int rollover

The digit to rollover on. On a car speedometer this would be 10

permute

protected final boolean permute

Are we generating only valid permutations? Or are we a normal odometer?

ongoing

protected boolean ongoing

We are done when we have generated the last valid odometer setting before a complete rollover

Constructor Detail

Odometer

public Odometer(int digits,
                int rollover)

Constructs a normal (non-permuting) odometer.

Odometer

public Odometer(int digits,
                int rollover,
                boolean permute)

Method Detail

hasNext

public boolean hasNext()

Specified by:

hasNext in interface java.util.Iterator

remove

public void remove()

Specified by:

remove in interface java.util.Iterator

next

public java.lang.Object next()

Specified by:

next in interface java.util.Iterator

nextPosition

public int[] nextPosition()

main

public static void main(java.lang.String[] args)