How does this bubble sort work? (Java array)

[Energize]

My oracle book doesn't explain this very well.

class bubble{
public static void main(String[] args){
int nums[]={99, -10, 100123, 18, -987, 5623, 463, -9, 287, 49};

int a, b, t;
int size=10;

System.out.println("Original array is:");
for(int i=0;i<size;i++)
System.out.println(" "+nums[i]);
System.out.println();

for(a=1;a<size;a++)
for(b=size-1;b>=a;b--){
if(nums[b-1]>nums[b]){

t=nums[b-1];
nums[b-1]=nums[b];
nums[b]=t;
}}

System.out.print("Sorted array is:");
for(int i=0;i<size;i++)
System.out.print(" "+nums[i]);
System.out.println();
}}

Can someone help explain to me how this works?