Initializing array with values - should I explicitly instance the class or not?

Question

I often see arrays being initialized like this:

String[] array = new String[] { "foo", "bar", "baz" };

But reading the Language Basics - Arrays shows that the short syntax doesn't require explicitly instancing the constructor:

Alternatively, you can use the shortcut syntax to create and initialize an array:
 int[] anArray = { 
     100, 200, 300,
     400, 500, 600, 
     700, 800, 900, 1000
 };

So, assuming these two methods of initialization:

String[] array = new String[] { "foo", "bar", "baz" };
String[] array2 = { "foo", "bar", "baz" };

Is there any difference between these? Both seems to work the same, in that case should I assume that the second one implicitly calls the new String[] and the first one is just a more verbose way, or is there more to it behind the scenes?

Starting with Java so sorry if this is way too stupid of a question, but I couldn't find anything about this in the web.

Community · Accepted Answer · 2017-05-23 12:09:30Z

21

The two methods are equivalent. Note, however, that the concise syntax can only be used in variable declarations. Outside variable declarations you have to use the verbose syntax:

    String[] array;
    array = new String[] { "foo", "bar", "baz" }; // OK

    String[] array2;
    array2 = { "foo", "bar", "baz" };             // ERROR

For further discussion, see this answer.

edited May 23, 2017 at 12:09

CommunityBot

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answered Mar 2, 2013 at 17:43

NPE

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Comments

Matt Ball · Accepted Answer · 2013-03-02 17:44:08Z

7

Is there any difference between these?

There is no difference in the end result. However, as per the JLS § 10.6, you cannot use the array initializer synax in every context.

An array initializer may be specified in a declaration (§8.3, §9.3, §14.4), or as part of an array creation expression (§15.10), to create an array and provide some initial values.

answered Mar 2, 2013 at 17:44

Matt Ball

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1 Comment

Fabrício Matté Over a year ago

I do love spec links, thanks very much. But I believe NPE's answer is more clear/simpler for future Java starters that may come to read the question. +1 for both in any case. =]

irreputable · Accepted Answer · 2013-03-02 17:51:19Z

0

Since arrays are intended to be mutable, it makes sense that each one is a new instance

String[] array1 = { "foo", "bar", "baz" };
String[] array2 = { "foo", "bar", "baz" };

i.e. modifying array1 won't affect array2.

answered Mar 2, 2013 at 17:51

irreputable

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1 Comment

Fabrício Matté Over a year ago

I have a decent OO base and understand that each array is a new instance, the question was specifically whether new String[] made any difference in the initialization of the array.

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