How does Java calculate length of primitive array?

Question

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)

@RaulRene - You are right. I wasn't searching with the right words. — Farhan Syed, Mar 06 '14 at 08:05

score 8 · Accepted Answer · edited Mar 06 '14 at 08:06

8

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...

edited Mar 06 '14 at 08:06

yshavit

41,077
7
83
120

answered Mar 06 '14 at 07:58

user949300

15,154
6
33
65

1

You are right. I was able to do chars.getClass() and it printed "class [C". – Farhan Syed Mar 06 '14 at 08:11

score 3 · Answer 2 · answered Mar 06 '14 at 07:57

3

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.

answered Mar 06 '14 at 07:57

dbf

6,251
2
30
60

score 0 · Answer 3 · answered Mar 06 '14 at 07:55

0

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

Or am I missing the question?

answered Mar 06 '14 at 07:55

Scary Wombat

43,525
5
33
63

score 0 · Answer 4 · edited May 23 '17 at 12:09

0

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.

edited May 23 '17 at 12:09

Community

1
1

answered Mar 06 '14 at 07:59

Turix

4,482
2
17
27

How does Java calculate length of primitive array?

4 Answers4