Final answer:
The Java expression to determine the number of elements in an array is b.length. This expression will return the length of the array b.
Step-by-step explanation:
The Java expression to determine the number of elements in an array is b.length. This expression will return the length of the array b, which indicates how many elements are present in the array.
For example, if the array b has 5 elements, then the expression b.length will evaluate to 5.
Using this expression, you can easily retrieve the number of elements in an array in Java.