can someone explain it to me?

Question

public class Main {

public static void main(String[] args) {
int[]a = {1,2, 3, 4, 1};
for(int n: a){
a[n]=0;
}
for (int n:a){
System.out.println(n);
}
}
}

Answer 1

Explanation in comments.
https://code.sololearn.com/c0pij3z7g868/?ref=app

Answer 2

It sets certain elements in a to 0, but not all.
First iteration n=a[0]=1 sets a[1] to 0
Second iteration n=a[1]=0 (because a[1] was set to 0 in first iteration) sets a[0] to 0
And so on

The trick to understand is that updates are immediate

Answer 3

Thanks for this explanation i was thinking why it's not working as index a[0]=1
a[1]=2
a[2]=3
..