集合 TreeSet HashMap

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());
}
}
}

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"));
}

}