集合 TreeSet HashMap

SetTest类：

package com.jinhuapkg;import java.util.Iterator;import java.util.TreeSet;public class SetTest {    public static void main(String[] args){        TreeSet treeSet = new TreeSet();        treeSet.add("hello");        treeSet.add("hi");        treeSet.add("well");        treeSet.add("ok");        Iterator iterator = treeSet.iterator();        while (iterator.hasNext()){            System.out.println(iterator.next());        }        }}

MapTest类：

package com.jinhuapkg;import java.util.HashMap;public class MapTest {    public static void main(String[] args) {        HashMap hashMap = new HashMap();        hashMap.put("1", "aaa");        hashMap.put("2", "bbb");        System.out.println(hashMap.get("1"));    }}