Bubble sort is one of the simplest sorting algorithms. The two adjacent elements of an array are checked and swapped if they are in wrong order and this process is repeated until we get a sorted array. The steps of performing a bubble sort are:
- Compare the first and the second element of the array and swap them if they are in wrong order.
- Compare the second and the third element of the array and swap them if they are in wrong order.
- Proceed till the last element of the array in a similar fashion.
- Repeat all of the above steps until the array is sorted.
This will be more clear by the following visualizations.
Initial array
First iteration
SWAP
SWAP
Second iteration
SWAP
SWAP
Third iteration
No swap → Sorted → break the loop
Let’s code this up.
class Sort
{
public static void main (String[] args)
{
int a[] = {16, 19, 11, 15, 10, 12, 14};
for(int j = 0; j<a.length; j++)
{
//initially swapped is false
boolean swapped = false;
int i = 0;
while(i<7-1)
{
//comparing the adjacent elements
if (a[i] > a[i+1])
{
//swapping
int temp = a[i];
a[i] = a[i+1];
a[i+1] = temp;
//Changing the value of swapped
swapped = true;
}
i++;
}
//if swapped is false then the array is sorted
//we can stop the loop
if (!swapped)
break;
}
for(int x : a)
{
System.out.println(x);
}
}
}
In this code, we are just comparing the adjacents elements and swapping them if they are not in order. We are repeating this process 7 times (number of elements in the array). We have also assigned a variable ‘swapped’ and making it ‘true’ if any two elements get swapped in an iteration. If no interchanging of elements happens then the array is already sorted and thus no change in the value of the ‘swapped’ happens and we can break the loop.
