给定一个字符串,求出该字符串里哪个字符出现的次数最多

package org.crm.test;

import java.util.HashMap;
import java.util.Map;

public class StrCartTest {

/**
* @param args
*/
public static void main(String[] args) {
   // TODO Auto-generated method stub
        String str = "gsagsagststsgdgdfgdrgergdgdfgertgdattw";
        int length = str.length();
        Map map = new HashMap();
        for (int i = 0; i < length; i++) {
    char zi = str.charAt(i); //截取每个字符
    if (map.containsKey(zi)) { //判断字符是否在map集合当中
     Integer count = map.get(str.charAt(i)); //获取保存的key对应的value
     count++; //添加1
     map.put(zi, count); //重新保存
    }else{
     map.put(zi, 1); //首次保存
    }
   } 
        Object [] keys = map.keySet().toArray();
        int size = keys.length;
        Integer [] a = new Integer[size] ;
        map.values().toArray(a);

        //冒泡排序
        int temp = 0;
        for (int i = 0; i < size-1; i++) {
    for (int j = i; j < size-i-1; j++) {
     if (a[j]>a[j+1]) {
      temp = a[j];
      a[j] = a[j+1];
      a[j+1] = temp;
     }
    }
   }
        //获的排序前的集合
        Integer [] old = new Integer[size] ;
        map.values().toArray(old);
        //打印结果
        for (int i = 0; i < size; i++) {
    int num = a[i];
    for (int j = 0; j < size; j++) {
     if(num==old[j]){
      System.out.println(keys[j]+"："+num);
      break ;
     }
    }
   }
}

}