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

public class Test {

   public static void main(String[] args) {
       String randLetterInfo = "ajfoaifjalfajweoagaefalwfgjaoevawjaiwefjawoefiaf";

       Test test = new Test();
       test.countCharOfStr(randLetterInfo);
   }

   /**
    * 计算特定字符的重复的次数数，并打印到控制台
    *
    * @param inputLetterInfo 字符串
    */
   public void countCharOfStr(String inputLetterInfo) {
       char[] letterCharArray = inputLetterInfo.toCharArray();

       Map<Character, Integer> opMap = new HashMap<>();
       for (char c : letterCharArray) {
           opMap.put(c, opMap.get(c) == null ? 1 : opMap.get(c) + 1);
       }

       Iterator iter = opMap.keySet().iterator();
       while (iter.hasNext()) {
           char c = (Character) iter.next();
           System.out.println(c + " = " + opMap.get(c));
       }
   }
}

运行结果如下：