sets.java

看thinkinjava学习java时

package myutils;
import java.util.*;
public class Sets {
	public static <T> Set<T> union(Set<T> a,Set<T> b){
		Set<T> result = new HashSet<T>(a);
		result.addAll(b);
		return result;
	}
	public static <T>
	Set<T> intersection(Set<T> a,Set<T> b){
		Set<T> result = new HashSet<T>(a);
		result.retainAll(b);
		return result;
	}
	public static <T> Set<T>
	difference(Set<T> superset,Set<T> subset){
		Set<T> result = new HashSet<T>(superset);
		result.retainAll(subset);
		return result;
	}
	public static <T> Set<T> complement(Set<T> a,Set<T> b){
		return difference(union(a,b),intersection(a,b));
	}

}