How do I declare an array in Java?
+10
A:
You can either use array declaration or array literal (but only when you declare and affect the variable right away, array literals can not be used for re-assigning an array).
For primitive types :
int[] myIntArray = new int[3];
int[] myIntArray = {1,2,3};
int[] myIntArray = new int[]{1,2,3};
For Objects, like Strings :
String[] myStringArray = new String[3];
String[] myStringArray = {"a","b","c"};
String[] myStringArray = new String[]{"a","b","c"};
subtenante
2009-07-29 14:25:23
I fail to see the difference between the two, but maybe that's just me ...
Jean
2009-07-29 14:32:48
The answer sounds like "String" is not a type. Can you please elaborate?
Johannes Schaub - litb
2009-07-29 15:57:58
String is an object, not a primitive type. The author is saying that this method works with both.
bestattendance
2009-07-29 16:08:37
For those asking, no there is no difference between primitive type and Object array declaration / instantiation. Although there is. Because Java is like that. Or not. (Still, seriously, because there are differences in syntax for other things, I found it interesting to mention both cases. )
subtenante
2009-07-30 09:28:17
+1
A:
Alternatively,
// Either method works
String arrayName[] = new String[10];
String[] arrayName = new String[10];
That declares an array called arrayName of size 10 (you have elements 0 through 9 to use).
Thomas Owens
2009-07-29 14:25:31
+3
A:
There are a various ways in which you can declare an array in Java:
float floatArray[]; //initialize later
int[] integerArray = new int[10];
String[] array = new String[] {"a", "b"};
You can find more information on the Sun Tutorial site and the JavaDoc.
Anirudh
2009-07-29 14:28:14
+4
A:
Type[] variableName = new Type[capacity];
Type[] variableName = {comma-delimited values};
Type variableName[] = new Type[capacity];
is also valid, but I prefer the brackets after the type, because it's easier to see that the variable's type is actually an array.
Nate
2009-07-29 14:29:17
I agree on that point. The type of the variable is not "TYPE", but actually a TYPE[], so it makes sense to write it that way for me.
Chet
2009-07-29 14:31:04
+1
A:
I find its helpful if you understand each part:
Type[] name = new Type[5];
Type[] is the type of the variable called name. The keyword 'new' says to allocate memory for the new array. The number between the bracket says how large it will be and how much memory to allocate.
You can also create arrays with the values already there, such as
int[] name = {1, 2, 3, 4, 5};
which not only creates the empty space but fills it with those values.
Chet
2009-07-29 14:29:56
A:
Also, in case you want something more dynamic there is the List interface. This will not perform as well, but is more flexible:
List listOfString = new ArrayList();
listOfString.add("foo"); listOfString.add("bar");
String value = listOfString.get(0);
assertEquals( value, "foo" );
Dave
2009-07-29 15:56:20