Using Bubble Sort in Java

Printing QR Code ISO/IEC18004 in Java Using Bubble Sort

The simplest way to sort any amount of data is to start at the beginning and compare the first two adjacent items So if you need to sort a list of numbers, you compare the first number with the second number If the first number is bigger, you swap its place with the second number If the second number is bigger, you don t do anything at all After comparing the first two items, you move down to comparing the second and third items, and so on Repetitively comparing two adjacent items is the basic idea behind the bubble sort algorithm, as shown in Figure 1-1 The bubble sort algorithm gets its name because small values tend to bubble up to the top

Basically the bubble sort algorithm works like this:

1 Compare two adjacent items 2 Swap the two items if necessary 3 Repeat Steps 1 and 2 with each pair of adjacent items 4 Repeat Steps 1 3 to examine the entire list again until no swapping

occurs and then the list is sorted Although the bubble sort algorithm is easy to implement, it s also the slowest and most inefficient algorithm because it must examine an entire list multiple times For sorting a small list of pre-sorted data, the bubble sort algorithm works efficiently For sorting large lists of unsorted data, any other sorting algorithm is much faster than the bubble sort algorithm, as shown in Figure 1-2

Step #1 74 32 21

Step #1

Step #5

Step #6

Step #3

Step #4

Another simple way to sort a list is to search the entire list until you find the smallest value Then move that value to the front of the list Now repeat the process all over again, skipping the first item By repetitively searching for the smallest item and moving it to the front of the list, the selection sort algorithm can eventually sort an entire list, as shown in Figure 1-3 The selection sort algorithm works like this:

1 Find the smallest item in a list 2 Swap this value with the value currently at the front of the list 3 Repeat Steps 1 and 2 with the current size of the list minus one (list

size = list size 1)

The smallest number of the list (9) gets swapped with the first number of the list (32)

The smallest number (21) of the remaining unsorted items gets swapped with the first number of the unsorted list (32)

The smallest number (32) of the remaining unsorted items gets swapped with the first number of the unsorted list (74)

For sorting small lists, selection sort is fast, but for sorting large lists, selection sort needs too much time progressively examining smaller sections of a list Despite this drawback with sorting large lists, selection sort is popular because it s simple to implement

The insertion sort algorithm acts like a cross between the bubble sort and the selection sort algorithm Like bubble sort, insertion sort examines two adjacent values Like selection sort, insertion sort moves smaller values from their current location to an earlier position near the front of the list The insertion sort algorithm works like this:

1 Start with the second item in the list 2 Compare this second item with the first item If the second value is

The main difference between insertion sort and selection sort is that the selection sort only swaps two adjacent values whereas insertion sort can move a value to a non-adjacent location, as shown in Figure 1-4

32 9 32

9 21 9

One major advantage of the insertion sort algorithm is that it only needs to examine an entire list once to sort it In comparison, bubble sort must repetitively examine the entire list multiple times, and selection sort must repetitively examine progressively smaller lists multiple times As a result, the insertion sort algorithm is much faster while being easy to implement as well