Which code runs faster?

Question

I have two piece of code, and I want to know which is faster when they run and why it's faster. I learn less about JVM and CPU, but I'm hard working on them. Every tip will help.

int[] a=new int[1000];
int[] b=new int[10000000];
long start = System.currentTimeMillis();
//method 1
for(int i=0;i<1000;i++){
    for(int j=0;j<10000000;j++){
        a[i]++;
    }
}
long end = System.currentTimeMillis();
System.out.println(end-start);

start=System.currentTimeMillis();
//method 2
for(int i=0 ;i<10000000;i++){
    for(int j=0;j<1000;j++){
        b[i]++;
    }
}
end = System.currentTimeMillis();
System.out.println(end-start);

Answer 1

I'll throw my answer in there, in theory they will be exactly the same but in practice there will be a small, but negligible, difference. Too small to really matter, actually.

The basic idea is how array b is stored in memory. Because it is a lot larger, depending on your platform/implementation it might be stored in chunks, aka non-contiguously. That is likely since an array of 10 million ints is 40 million bytes = 40 MB!

EDIT: I get 572 and 593, respectively.