xyz.jmburns.rangefun

Class Progression

java.lang.Object

xyz.jmburns.rangefun.Progression

All Implemented Interfaces:

java.lang.Comparable<Progression>, java.lang.Iterable<java.lang.Integer>

public final class Progression
extends java.lang.Object
implements java.lang.Iterable<java.lang.Integer>, java.lang.Comparable<Progression>

This class represents an progression of integers, as built by the Progressions API. The class is also fully suitable for use in Map and Collection instances, since it provides well-behaved implementations of equals, hashCode, and compareTo. It is also completely immutable, and is thus guaranteed to be thread-safe.

Method Summary

Modifier and Type	Method and Description
int	compareTo(Progression other)
boolean	contains(int integer) Determines whether or not iteration over this progression would produce the given integer.
boolean	equals(java.lang.Object object)
int	get(int index) Returns the integer at the specified index in the progression.
int	hashCode()
java.util.Iterator<java.lang.Integer>	iterator()
int	length() Calculates the length of this progression, with the step value taken into account.
Progression	reverse() Creates a new Progression instance whose starting value is this progression's ending value, and vice versa.
java.lang.Integer[]	toArray() Returns a new Integer array filled with all the integers in this progression, in iteration order.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Method Detail

reverse

public Progression reverse()

Creates a new Progression instance whose starting value is this progression's ending value, and vice versa. This method is intended to be used to easily iterate backwards over an array.

Returns:

a new Progression instance, created from this one, but with values swapped so that the progression is iterated backwards.

contains

public boolean contains(int integer)

Determines whether or not iteration over this progression would produce the given integer. For example, Progressions.progression(1, 5, 2).contains(3) would evaluate to true, while Progressions.range(7, 5).contains(4) would evaluate to false.

Parameters:

integer - the integer whose range is to be evaluated

Returns:

true if iteration over this progression would produce the given integer, false otherwise

See Also:

Progressions.progression(int, int, int), Progressions.range(int, int)

Implementation Note:

Progressions are lazily-evaluated, so this method is guaranteed to run in constant time.

get

public int get(int index)

Returns the integer at the specified index in the progression. Indexing begins at zero. For example, Progressions.range(5, 9).get(2) would evaluate to 7, since 7 is the third (counting from zero) integer in the range of 5, 6, 7, 8, 9.

Parameters:

index - the index to look up

Returns:

the integer at the specified index in the progression

See Also:

toArray(), Progressions.range(int, int)

Implementation Note:

Progressions are lazily-evaluated, so repeated calls to get(int) may not provide optimal performance. In those cases, it might be worth calling toArray() and accessing the returned array by index instead, since it would produce the same results, without unnecessary recalculation.

toArray

public java.lang.Integer[] toArray()

Returns a new Integer array filled with all the integers in this progression, in iteration order. For example, Progressions.range(1, 5).toArray() will evaluate to an array containing the integers 1, 2, 3, 4, 5.

Returns:

a new Integer array filled by all the integers in this progression

See Also:

Progressions.range(int, int)

length

public int length()

Calculates the length of this progression, with the step value taken into account.

Returns:

the length of the progression

iterator

public java.util.Iterator<java.lang.Integer> iterator()

Specified by:

iterator in interface java.lang.Iterable<java.lang.Integer>

Returns:

a new Iterator over this progression

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

equals

public boolean equals(java.lang.Object object)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

compareTo

public int compareTo(Progression other)

Specified by:

compareTo in interface java.lang.Comparable<Progression>