intersection and union in java (bit strings)

Question

What is the operation used in java to represent Intersection and Union?

For example, {a,c} = 101 {c,b} = 011 and the interaction result should be 001. If I want to represent this in java 101 ∩ 011 what is the operation that should be used in correspond to ∩ and ∪ ?

Assuming you're using Java 8, see the answer here from Silas Reinagel: http://stackoverflow.com/questions/31683375/java-8-lambda-intersection-of-two-lists — peter.petrov, Jan 18 '16 at 22:19

score 2 · Answer 1 · answered Jan 18 '16 at 22:20

2

See the section set interface bulk operations in the official documentation. You want addAll and retainAll.

answered Jan 18 '16 at 22:20

bmargulies

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Rafael · Answer 2 · 2016-01-18T22:28:06.453

Have a look to the Set Interface.

According to the above website:

s1.addAll(s2) — transforms s1 into the union of s1 and s2. (The union of two sets is the set containing all of the elements contained in either set.)
s1.retainAll(s2) — transforms s1 into the intersection of s1 and s2. (The intersection of two sets is the set containing only the elements common to both sets.)

Here is an example:

import java.util.HashSet;
import java.util.Set;
public class Intersection
{
   public static void main(String[] args)
   {
      Set<String> s1 = new HashSet<String>();
      Set<String> s2 = new HashSet<String>();

      s1.add("a");
      s1.add("c");

      s2.add("b");
      s2.add("c");

      s1.retainAll(s2);

      System.out.println(s1);
   }
}

The output of the above is:

[c]

intersection and union in java (bit strings)

2 Answers2