Commons Lang、BitField#set()

import org.apache.commons.lang.BitField;

public class C2009042900 {
    public static void main(String[] args) {
        BitField bf;

        bf = new BitField(5);
        System.out.println(bf.set(1) + " " + bf.getValue(15));

        bf = new BitField(5);
        System.out.println(bf.set(2) + " " + bf.getValue(15));

        bf = new BitField(5);
        System.out.println(bf.set(15) + " " + bf.getValue(15));
    }
}

で、

5 5
7 5
15 5