Could anybody explain why j = - 2 in this code? (Java)

Question

public class Program
{
public static void main(String[] args) {
int i = 0, j = 0, k = 0;
while(i < 2) {
j = i++;
System.out.println("step 1 i = " + i);
System.out.println("step 1 j = " + j);
while(j-- >= 0)
k = k + ((j % 2 == 0) ? -1 : 1);
System.out.println("step 2 j = " + j);
System.out.println("step 2 k = " + k);
}
System.out.println("final i = " + i);
System.out.println("final j = " + j);
System.out.println("final k = " + k);
}
}

Output
step 1 i = 1
step 1 j = 0
step 2 j = - 2
step 2 k = 1
step 1 i = 2
step 1 j = 1
step 2 j = - 2
step 2 k = 1
final i = 2
final j = - 2
final k = 1

Answer 1

That's because of postfix decrement.

Let's say after some iterations j = 0

the condition will be checked
0 >= 0, (True)
j--; ---> j = -1

As condition is true, compiler will get inside the loop and condition will be checked again
1 >= 0, (False)
j--; ---> j = -2

Now condition is false, loop will be terminated. And final value of j is -2.