Storing array of single bits

Question

Hi, I have an object in my application which is hogging memory as there is up to 3million
of them in memory at one time and i am trying to cut down the size of it.
the core data structure is an array of 1's and zero's.
currently i'm using a byte[] to store these.
Because i know i only ever want to store a 1 or a 0 at each index, is there a way of storing
these as a boolean[] {1bit of storage in my understanding} so that i can save memory

Answer 1

Here's an example of packing 8 of your bytes from the array into a byte, then unpacking it into a String.
        byte[] ba        = {0, 0, 1, 0, 1, 0, 1, 0};
        // when packed into a byte the array value is decimal 42
        //Pack a byte
        byte packedByte  =
            (byte) ((byte) ((ba[0] & 0xf) << 7) |
                    (byte) ((ba[1] & 0xf) << 6) |
                    (byte) ((ba[2] & 0xf) << 5) |
                    (byte) ((ba[3] & 0xf) << 4) |
                    (byte) ((ba[4] & 0xf) << 3) |
                    (byte) ((ba[5] & 0xf) << 2) |
                    (byte) ((ba[6] & 0xf) << 1) |
                    (byte) ((ba[7] & 0xf) << 0));
        System.out.println("The byte value is " + packedByte);
        //Unpack a byte
        String UnpackedByte = Integer.toBinaryString(packedByte);
        System.out.println("The binary string is " + UnpackedByte);