关于Java的HashMap使用.想产生40个随机数,从10-50,然后分别统计各个数字出现的次数.

关于Java的HashMap使用.想产生40个随机数,从10-50,然后分别统计各个数字出现的次数.package com.jl;import java.util.HashMap;import java.util.Iterator;import java.util.Random;import java.util.Set;public class Practice {public static void main(String[] args) {HashMap map = new HashMap();for (int i = 0; i < 50; i++){Random r = new Random();int num = (r.nextInt(41) + 10);map.put(new Integer(i),new Integer(num));System.out.println(num);}HashMap map2 = new HashMap();Set set = map.keySet();Set set2 = map.keySet();for (Iterator iter = set.iterator(); iter.hasNext();){Integer key = (Integer) iter.next();Integer value = (Integer) map.get(key);Iterator iter2 = set2.iterator();Integer key2 = (Integer) iter2.next();Integer abc = (Integer) map2.get(key2);if (abc == null){int k = 1;map2.put(value,new Integer(k));} else{Integer in = (Integer)map2.get(key2);in = new Integer(in.intValue() + 1);map.put(value,in);}}Set abc = map2.keySet();for (Iterator iter = abc.iterator(); iter.hasNext();){Integer key = (Integer) iter.next();Integer value = (Integer) map2.get(key);System.out.println(key + " :" + value);}}}