TreeMap用法 示例

/*

TreeMap类通过使用树来实现Map接口.TreeMap提供了按排序顺序存储关键字/值对的有效手段，同时允许快速检索。不像散列映射，树映射保证它的元素按照关键字升序排序。

*/

import java.util.*;
class TreeMapDemo{
public static void main(String[] args)
{
//Creat a tree map
TreeMap tm = new TreeMap();

//Put elements to the map
tm.put("Evan",new Double(12345.77));
tm.put("Rose",new Double(78777));
tm.put("Magic",new Double(-99.10));
tm.put("Mike",new Double(100.00));
tm.put("Sue",new Double(17.15));

//Get a set of entries
Set set = tm.entrySet();

//Get an iterator
Iterator i = set.iterator();

//Display elements
while(i.hasNext()){
Map.Entry me = (Map.Entry)i.next();
System.out.println(me.getKey() + ": ");
System.out.println(me.getValue());
}
System.out.println();

//Deposit 1000 into Evan's account
double balance = ((Double)tm.get("Evan")).doubleValue();
tm.put("Evan",new Double(balance + 1000));
System.out.println("Evan's new balance : " + tm.get("Evan"));
}
}