Define Bubble sort?
Bubble sorting like a bubble. Highest weight number will move to top.
Array: [50,13,8,5,12]
Outer loop doing n  1 times
Inside loop moves the highest number to top one by one. Next time has no need to test moved bubble numbers. So inside looping is n  i  1.





index of array is starts from down to top 
50 moved to top as like bubble in water 
this move will not touch already moved 50 
this move will not touch already moved 50,13 
this move will not touch already moved 50,13, 12 

Example Bubble sort in JAVA
public class BubbleSort {
public static void display(int numbers[]){
for (int i=0;i<numbers.length;i++){
System.out.print(numbers[i]+"\t");
}
System.out.println();
}
public static void main(String args[]) throws Exception{
int numbers[] = {48,34,5,12,8};
for (int i=0;i<numbers.length1;i++){
for (int j=0;j<numbers.lengthi1;j++){
if (numbers[j] > numbers[j+1]){
int t = numbers[j+1];
numbers[j+1] = numbers[j];
numbers[j] = t;
}
}
}
display(numbers);
}
}

Looping style
input array
[50,13,8,5,12]
i = 0; j:0 to ni
[50,13,8,5,12]
[13,50,8,5,12]
[13,8,50,5,12]
[13,8,5,50,12]
[13,8,5,12,50]
i=1; j: 0 to ni
[8,13,5,12,50]
[8,5,13,12,50]
[8,5,12,13,50]
i=2; j: 0 to ni
[5,8,12,13,50]
i=3; j: 0 to ni
[5,8,12,13,50]
