For int[] numbers = {1, 2, 3, 4, 5}, which indexes are valid?
int[] numbers = {1, 2, 3, 4, 5}
Only indexes whose numbers already appear as element values are valid.
Indexes 1 through numbers.length, which are 1 through 5.
numbers.length
Indexes 0 through numbers.length - 1, which are 0 through 4.
numbers.length - 1
Every integer index is accepted because arrays resize automatically.