BitSet Index Sets

BitSet Index Sets

Save as Main.java and run with a Java 17+ JDK: java Main.java.

import java.util.BitSet;

public class Main {
  public static void main(String[] args) throws Exception {
    BitSet available = new BitSet();
    available.set(1); available.set(3); available.set(5);
    BitSet requested = new BitSet();
    requested.set(3); requested.set(4);
    BitSet shared = (BitSet) available.clone();
    shared.and(requested);
    System.out.println(shared);
    System.out.println(available.cardinality());
  }
}

1. Expected output: {3} 3
2. and mutates its receiver. Cloning first preserves the original set, whose three bits remain active.