java string array : is there a size of method?

Question

I come from a php background and in php, there is an array_size() function which tells you how many elements in the array are used. Is there a similar method for a String[] array?

thanks

Answer 1

array.length

It is actually a final member of the array, not a method.

Answer 2

array.length final property

it is public and final property. It is final because arrays in Java are immutable by size (but mutable by element's value)

Answer 3

Yes .length

    String[] array = new String[10];
    int size = array.length;

Answer 4

Arrays are objects and they have a length field.

String[] haha = {"olle", "bulle"};

haha.length would be 2

Answer 5

In java there is a length field that you can use on any array to find out it's size:

 String[] s = new String[10];
 System.out.println(s.length);

Answer 6

A bit off topic:

are you sure that php has a array_size() function? I don't see one here

Answer 7

Not really the answer to your question, but if you want to have something like an array that can grow and shrink you should not use an array in java. You are probably best of by using ArrayList or another List implementation.

You can then call size() on it to get it's size.

Answer 8

The answer is "All of them". A java array is allocated with a fixed number of element slots. The "length" attribute will tell you how many. That number is immutable for the life of the array. For a resizable equivalent, you need one of the java.util.List classes - where you can use the size() method to find out how many elements are in use.

However, there's "In use" and then there's In Use. In an class object array, you can have element slots whose elements are null objects, so even though they count in the length attribute, but most people's definitions, they're not in use (YMMV, depending on the application). There's no builtin function for returning the null/non-null counts.

List objects have yet another definition of "In Use". To avoid excessive creation/destruction of the underlying storage structures, there's typically some padding in these classes. It's used internally, but isn't counted in the returned size() method. And if you attempt to access those items without expanding the List (via the add methods), you'll get an illegal index exception.

So for Lists, you can have "In Use" for non-null, committed elements, All committed elements (including null elements), or All elements, including the expansion space presently allocated.

Answer 9

If you want a function to do this

Object array = new String[10];
int size = Array.getlength(array);

This can be useful if you don't know what type of array you have e.g. int[], byte[] or Object[].