疯狂java讲义习题7.3

题目描述：
给定["a","b","a","b","c","a","b","c","b"]字符串数组，然后使用Map的Key来保存数组中字符串元素，value保存该字符串出现的次数，最后统计出各字符串元素的出现次数
代码如下：

import java.io.*;
import java.util.*;
public class cmd {
    public static void main(String args[])
    {
        String str[] = {"a","b","a","b","c","a","b","c","b"};
        HashMap hm = new HashMap();
        int count1 = 0,count2 = 0,count3 = 0;
        for (int i = 0;i < str.length;i++)
        {

            if (str[i].equals("a"))
            {

                count1++;
            }
            else if (str[i].equals("b"))
            {
                count2++;
            }
            else if (str[i].equals("c"))
            {
                count3++;
            }
            else{}
        }

        hm.put("a",count1);
        hm.put("b",count2);
        hm.put("c",count3);
        System.out.println(hm);


    }

}

运行结果如下：
{b=4, c=2, a=3}