How does Java calculate length of primitive array? [duplicate]

Question

This question already has answers here:

Where is array's length property defined? (7 answers)

Closed 9 years ago.

Code:

char[] chars = "abcd".toCharArray();
System.out.println(chars.length);

Question: How is length calculate by Java here? Since char is not a Class, I am not sure where length is stored. If it isn't stored, is it calculated every time you do chars.length? (I presume not)

Answer 1

The thing you wrote as char[] is an Object, an array, and has a public final field called length. It is calculated once when the array in created. Like all objects it also has a toString(), notify(), etc...

Answer 2

http://docs.oracle.com/javase/specs/jls/se7/html/jls-10.html#jls-10.7

The public final field length, which contains the number of components of the array. length may be positive or zero.

Answer 3

In this case chars.length is returning the number of elements in the array.

Or am I missing the question?

Answer 4

Even though char is not a Class/Object type in Java, an array of char actually is. And the length is a (final) field of that class. See the answer here for more.