If I use a statement in my code like
int[] a = new int[42];
Will it initialize the array to anything in particular? (e.g. 0) I seem to remember this is documented somewhere but I am not sure what to search for.
+4
A:
When created, arrays are automatically initialized with the default value of their type - in your case that would be 0. The default is false for boolean and null for all reference types.
Bozhidar Batsov
2010-05-31 15:42:06
+11
A:
At 15.10 Array Creation Expressions the JLS says
[...] a single-dimensional array is created of the specified length, and each component of the array is initialized to its default value
and at 4.12.5 Initial Values of Variables it says:
For type
int, the default value is zero, that is,0.
p00ya
2010-05-31 15:45:14
A:
All elements in the array are initialized to zero. I haven't been able to find evidence of that in the Java documentation but I just ran this to confirm:
int[] arrayTest = new int[10];
System.out.println(arrayTest[5]) // prints zero
haldean
2010-05-31 15:45:21
Testing a specific implementation is not a good way to verify that every implementation behaves this way. It's better to check the documentation/specification, because if it isn't specified/documented then other implementations could handle it differently. That's more of problem in other languages, because Java has very few places with undefined/implementation-specific behaviour, but it's still true.
Joachim Sauer
2010-05-31 15:54:59
Further more - if it's ain't in the spec - behavior can be changed on a newer version of the same implementation.
duduamar
2010-05-31 16:00:30
A:
The array would be initialized with 42 0's
For other data types it would be initialized with the default value ie.
new boolean[42]; // would have 42 false 's
new double[42]; // would have 42 0.0 ( or 0.0D )
new float[42];// 42 0.0f 's
new long[42]; // 42 0L 's
And so on.
For objects in general it would be null:
String [] sa = new String[42]; // 42 null's
Date [] da = new Date[42]; // 42 null's
OscarRyz
2010-05-31 16:10:06