Problem: ArrayList of Booleans #
Plan A: var xs = new ArrayList<Boolean>();
xs -> ArrayList(Boolean data[], int size)
data -> Array[d0, d1, d2, ...]
dX -> Boolean(bool val)
So each boolean is in an object with:
- 16 byte object header, 1 byte for the value
- That’ll probably align to 24 bytes.
- A reference to it that’s another 8 bytes
- So likely 32 bytes = 256 bits per boolean.
- We should be able to store a boolean in one bit. How?
Plan B: Numbers are made out of bits.
- e.g. A byte is 8 bits.
- So instead of a Boolean[], or even a bool[], we use a byte[].
- We’re kind of doing the opposite of a generic structure.
- We’re specializing ArrayList for bits.
Operations to implement: get, set, add, size.
