Set 规则集

import java.util.*;


public class Hash {
	public static void main(String[] args){
		HashSet<String> hs=new HashSet<String>();
		hs.add("a");
		hs.add("c");
		hs.add("b");
		hs.remove("a");
		//System.out.println(hs);
		Iterator<String> iterator=hs.iterator();
		LinkedHashSet<String> lk=new LinkedHashSet<String>();
		lk.add("sdfa");
		lk.add("aereqwr");
		lk.add("vbx");
		System.out.println(lk);
		TreeSet<String> tree=new TreeSet<String>();
		tree.add("b");
		tree.add("y");
		tree.add("e");
		tree.add("a");
		System.out.println(tree);
		System.out.println("first:"+tree.first());
		System.out.println("last"+tree.last());
		System.out.println("headSet:"+tree.headSet("e"));
		System.out.println("tailSet"+tree.tailSet("e"));
		System.out.println("lower e:"+tree.lower("e"));
		System.out.println("floor e:"+tree.floor("e"));
		System.out.println("ceiling e:"+tree.ceiling("e"));
		System.out.println("higher e:"+tree.higher("e"));
	}
}