org.incava.ijdk.util

Class Indexable

java.lang.Object

org.incava.ijdk.util.Indexable

public class Indexable
extends java.lang.Object

Wraps index calculations of a sequence similar to Ruby, where index -2 means the next-to-last element in a list.

Constructor Summary

Constructors

Constructor and Description
Indexable(java.lang.Integer size) Creates an instance.

Method Summary

Modifier and Type	Method and Description
java.lang.Integer	get(java.lang.Integer index) Converts index, which can be positive or negative, to an offset within the given size, representing the length of a list (including strings).

Methods inherited from class java.lang.Object

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

Constructor Detail

Indexable

public Indexable(java.lang.Integer size)

Creates an instance.

Parameters:

size - the size into which the index is applied

Method Detail

get

public java.lang.Integer get(java.lang.Integer index)

Converts index, which can be positive or negative, to an offset within the given size, representing the length of a list (including strings). A negative index will result in the distance from the end of the list, with index -1 meaning the last element in the list, -2 the second to last, etc. Returns null if any::

• the resulting index is out of range (< 0 or ≥ size)
• size is 0 or null
• the resulting value is out of range (such as getIndex(2, -3) or getIndex(1, 2))

Examples:

     Indexable idx = new Indexable(null);  
     idx.get(null, 0);  // == null

     idx = new Indexable(0);  
     idx.get(0, 0);     // == null

     idx = new Indexable(4);  
     idx.get(0);     // == 0
     idx.get(1);     // == 1
     idx.get(3);     // == 3
     idx.get(4);     // == null
     idx.get(-1);    // == 3
     idx.get(-2);    // == 2
     idx.get(-3);    // == 1
     idx.get(-4);    // == 0
     idx.get(-5);    // == null
 

Parameters:

index - the index within the size

Returns:

the offset value for the index for the given size