How to save a very large binary code in java

Question

I want to save a very large number like 111111111100000001010 in an ArrayList in java. After saving I should be able to find the number of bytes needed to save it. The number is found using a function String Find_code(int input). How can I efficiently save it in memory? For example 21 bits for 111111111100000001010.

Answer 1

Use a BitSet.

This class implements a vector of bits that grows as needed. Each component of the bit set has a boolean value. Individual indexed bits can be examined, set, or cleared.

Answer 2

If 111111111100000001010 is a binary number, then it will fit in an integer. Simply store it in an array list of integers ArrayList<Integer>.