/*     String name = "adsbsadgsadgtewterfsdf";     eg a-->6,b-->1 d-->3 ...     将字符串以a(字母)=>2(个数)存入Map集合框架中    思路:1.将字符串转换成字符数组.           2.定义一个Map集合,然后对字符数组进行遍历,如果Map集合中没有该元素就将该元素存入Map集合中,并定义一个计数器,将次数存入Map中,来达到目的  */ import java.util.*; class CharMapDemo {     public static void main(String[] args)     {         String str = "abcedsadgsadfasdfaa";         TreeMap<Character,Integer> tm = Pross(str);         System.out.println(tm);     }     public static TreeMap<Character,Integer> Pross(String str)     {             char[] charArray = str.toCharArray();             TreeMap<Character,Integer> tm = new TreeMap<Character,Integer>();             for (int x = 0; x < charArray.length ;x++ )             {                 if(!tm.containsKey(charArray[x]))                 {                     tm.put(charArray[x],1);                 }                 else                 {                     int count = tm.get(charArray[x])+1;                     tm.put(charArray[x],count);                 }             }             return tm;     } }