【容器：哈希表(Hash)】 3.4视频 例子

package coins;

import java.util.HashMap;
import java.util.Scanner;

public class Coin {
    private HashMap<Integer, String> CoinName = new HashMap<Integer, String>();
    
    public Coin()
    {
        CoinName.put(1, "penny");
        CoinName.put(5, "nickel");
        CoinName.put(10, "dime");
        CoinName.put(25, "quarter");
        CoinName.put(50, "half-dollar");
       //调试：告诉我这个哈希表有多少东西
        System.out.println(CoinName.keySet().size());    //先得到一个Key的集合，再求Size
       //调试：直接输出哈希表
        System.out.println(CoinName);
       //调试：遍历哈希表
        for(Integer k :CoinName.keySet())
        {
            String str;
            str = CoinName.get(k);
            System.out.println(str);
        }
                
    }
    
    public String GetName(int amount) 
    {
        if(CoinName.containsKey(amount))
            return CoinName.get(amount);
        else
            return "NOT FOUND";    
    }
    
    
    public static void main(String[] args) {
        
        Scanner in = new Scanner(System.in);
        int amount = in.nextInt();
        Coin coin = new Coin();
        String name = coin.GetName(amount);
        System.out.println(name);
        in.close();
    }
}