# Java Program - Bubble Sort

Bubble sort is the simplest sorting algorithm. The Bubble sort is based on the idea that every adjacent elements are compared and swapped if found in wrong order.

### Example:

To understand the bubble sort, lets consider an unsorted array *[1, 23, 10, -2]* and discuss each step taken to sort the array in ascending order. In every pass, two adjacent elements are checked and swapped if found in wrong order.

__First Pass__:*(1)* and *(23)* are compared and found in correct order(ascending order in this case). After that *(23)* and *(10)* are compared, since *(23>10)*, hence these numbers are swapped. Then *(23)* and *(-2)* are compared and swapped.

__Second Pass__:*(1)* and *(10)* are compared and found in correct order. Then *(10)* and *(-2)* are compared, since *(10>-2)*, hence these numbers are swapped. After that *(10)* and *(23)* are compared and found in correct order.

__Third Pass__:*(1)* and *(-2)* are compared, since *(1>-2)*, hence these numbers are swapped. After that *(1,10)* and *(10,23)* are checked and found in correct order.

## Implementation of Bubble Sort

public class MyClass { // function for bubble sort static void bubblesort(int Array[]) { int n = Array.length; int temp; for(int i=0; i<n; i++) { for(int j=0; j<n-i-1; j++) { if(Array[j]>Array[j+1]) { temp = Array[j]; Array[j] = Array[j+1]; Array[j+1] = temp; } } } } // function to print array static void PrintArray(int Array[]) { int n = Array.length; for (int i=0; i<n; i++) { System.out.print(Array[i] + " "); } System.out.println(); } // test the code public static void main(String[] args) { int[] MyArray = {1, 10, 23, 50, 4, 9, -4}; System.out.println("Original Array"); PrintArray(MyArray); bubblesort(MyArray); System.out.println("\nSorted Array"); PrintArray(MyArray); } }

The above code will give the following output:

Original Array 1 10 23 50 4 9 -4 Sorted Array -4 1 4 9 10 23 50

### Time Complexity:

The time complexity of bubble sort is *Θ(N²)* in all cases even if the whole array is sorted because the entire array need to be iterated for every element and it contains two nested loops.