# 01. Introduction to Sorting

In this section, we'll cover sorting. Before we get started, let's cover the base class and some sorting basics.

## Stable vs. Unstable

A sort that is stable means that order of elements with the same key are preserved.

For example, if I had a list of `{f, F, D, d, W, n, K, i}` and I wanted to sort alphabetically (ignoring the cases) I would have `{D, d, f, F, i, n, K}`. Since D and d, along with f and F have the same value in terms of precedence, the letter that appears before the other in the original list appears first in the sorted array.

## Sort class

All the lessons in the section will use code that inherits from the `Sort` class. We could use generics to sort different types of objects (with respective `.equals()`) methods, but we'll keep it simple and focus on the algorithmic parts.

``````/**
* Contains the functionalities of any class that is able to Sort an array of ints.
* @version 1.0.0 May 16, 2015.
*/
public class Sort {

/**
* Swap two elements in our int array.
* @param index1 First index
* @param index2 Second index
*/
public static void swap(int[] inputArray, int index1, int index2) {

int temp;

temp = inputArray[index1];
inputArray[index1] = inputArray[index2];
inputArray[index2] = temp;

}
} ``````

### Learn how data is stored

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