Thread: Intersection and Union of Three or more Sets

 
package SetTheory;
 
import java.util.HashSet;
import java.util.Set;
import java.util.TreeSet;
 
 
public class test {
 
	/**
	 * @param args
	 */
 
	  public static  Set intersection(Set setA, Set setB, Set setC) {
		    Set S = new TreeSet(setA);
		   S.retainAll(setB);
		   S.retainAll(setC);
		    return S;
		  }
 
	  public static  Set union(Set setA, Set setB, Set setC) {
		    Set M = new TreeSet(setA);
		    M.addAll(setB);
		    M.addAll(setC);
		    return M;
		  }
 
	  public static  Set notB (Set setA, Set setB, Set setC) {
		    setA.removeAll(setB);
		    setC.removeAll(setB);
		    setA.addAll(setC); 
	         return setA;
	 	  }
           public static  Set notA (Set setA, Set setB, Set setC) {
		    setB.removeAll(setA);
		    setC.removeAll(setA);
		    Set R = new TreeSet(setB);
		    R.addAll(setC);
 
		     return R;
		  }
 
	public static void main(String[] args) {
		TreeSet set1 = new TreeSet();
	    TreeSet set2 = new TreeSet();
	    TreeSet set3 = new TreeSet();
 
 
		set1.add('a');
		set1.add('d');
		set1.add('e');
		set1.add('g');
 
		set2.add('b');
		set2.add('d');
		set2.add('f');
		set2.add('g');
 
		set3.add('c');
		set3.add('f');
		set3.add('e');
		set3.add('g');
 
		System.out.println("Union:" + union(set1, set2, set3));
		System.out.println("Intersection:" + intersection(set1, set2, set3));
		System.out.println("B' = " + notB(set1, set2, set3));
		System.out.println("A' = " + notA(set1, set2, set3));
		}
 
}

output
Union:[a, b, c, d, e, f, g]
Intersection:[g]
B' = [a, c, e]
A' = [b, d, f, g]

the first difference output from B' is correct because B' = (A-B)+(C-B) = a,c,e
i am confused because of the output of A' = (B-A)+(C-A) i need to make the output to be b,f,c