Casting a boolean array in Java?

Question

Is there anything I can cast a boolean array to in Java? It would be nice if I could say

boolean[] bools = new boolean[8];
int j = (int)bools;

But I'm not sure if that's feasible in Java.

Answer 1

That syntax is not legal in Java.

What is it you are after? If you are looking for the length, you can do this:

int j = bools.length;

Answer 2

No, you can't do this with a boolean[] - but it sounds like you might want a BitSet which is a compact representation of a set of Boolean values.

Answer 3

If you want a bit pattern, I think you're better off using bitmasks e.g.

final int BIT_1 = 0x00000001;
final int BIT_2 = 0x00000002;

// represents a bit mask
int value;

// enable bit 2
value |= BIT_2

// switch off bit 1
value &= ~BIT_1

// do something if bit 1 is set...
if (value & BIT_1) {

etc. See here for more examples.

Answer 4

the size of Java booleans is implementation specific, and it's probably not a single bit in any case. if you want an easy way to manipulate bits, take a look at BitSet.

Answer 5

You can cast boolean[] to Object, but that's about it.

Answer 6

Here's one quick-and-dirty way to convert from a boolean[] to an integer:

static int intFromBooleanArray(boolean[] array) {
    return new BigInteger(Arrays.toString(array)
                          .replace("true", "1")
                          .replace("false", "0")
                          .replaceAll("[^01]", ""), 2).intValue();
}

example:

intFromBooleanArray(new boolean[] {true, false, true, false, true, false});
// => 42.