JAVA -HashMap 实例

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

public class Coin {
  private HashMap<Integer,String> coinnames = new HashMap<Integer,String>() ; 
  // 创建一个hashmap ,散列表
  public Coin() {
    coinnames.put(1,"penny") ; 
    coinnames.put(5,"dime") ; 
    coinnames.put(10, "quarter") ; 
    coinnames.put(50,"acsuur") ; 
    System.out.println("容器大小 : " + coinnames.size());
    for( Integer k : coinnames.keySet()) { 
      // keySet 是 所有键的集合 
      String s = coinnames.get(k) ; // 返回该键所对应的值是多少 ; 
      System.out.println(k+" : " + s);
    }
  }
  public String getName(int amount) {
    if(coinnames.containsKey(amount)) // 判断是否有这个键
      return coinnames.get(amount) ; 
    else
      return "Not found " ; 
  }
  public static void main(String[] args) {
    // TODO Auto-generated method stub
    Coin coin = new Coin() ; 
    Scanner in  = new Scanner(System.in) ; 
    int amount = in.nextInt() ; 
    
    String name = coin.getName(amount) ; 
    System.out.println(name);
  }

}