Convert a BigInteger into a BitSet. - Java java.util

Java examples for java.util:BitSet

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Description

Convert a BigInteger into a BitSet.

Demo Code


import java.math.BigInteger;
import java.util.BitSet;
import java.util.Map;

public class Main{
    public static void main(String[] argv) throws Exception{
        BigInteger i = new BigInteger("1234");
        System.out.println(bigIntToBitSet(i));
    }//w  w w  . j ava 2s  .  c  o  m
    /**
     * Convert a BigInteger into a BitSet.
     * @param i BigInteger to convert.
     * @return 
     */
    public static BitSet bigIntToBitSet(BigInteger i) {
        return BitSetUtils.fromByteArray(i.toByteArray());
    }
    public static BitSet fromByteArray(byte[] bytes) {
        BitSet bits = new BitSet();
        for (int i = 0; i < bytes.length * 8; i++) {
            if ((bytes[bytes.length - i / 8 - 1] & (1 << (i % 8))) > 0) {
                bits.set(i);
            }
        }
        return bits;
    }
    public static byte[] toByteArray(BitSet bits) {
        byte[] bytes = new byte[bits.length() / 8 + 1];
        for (int i = 0; i < bits.length(); i++) {
            if (bits.get(i)) {
                bytes[bytes.length - i / 8 - 1] |= 1 << (i % 8);
            }
        }
        return bytes;
    }
}

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