统计一个字符串中每一个字符出现的次数

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  /**
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   * 通过String.charAt(index)获取字符串中的字符
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   * @param str
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   */
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  public static void count(String str){
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    Map<Character, Integer> map = new HashMap<Character, Integer>();
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    int total = 0;
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    Character tmp = null;
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    for (int i=0;i<str.length(); i++) {
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      tmp = str.charAt(i);
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      total = 1;
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      if (map.containsKey(tmp)) {
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        total = map.get(tmp)+1;
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      }
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      map.put(tmp, total);
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    }
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    PrintUtill.printlnRule();
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    PrintUtill.println(map);
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  }
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  /**
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   * String.charAt(index)的变种，将最后存储的Character类型转为String类型
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   * @param str
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   */
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  public static void count2(String str){
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    Map<String, Integer> map = new HashMap<String, Integer>();
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    int total = 0;
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    String tmp = null;
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    String maxChar = str.charAt(0) + "";
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    int maxToal = 1;
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    for (int i=0;i<str.length(); i++) {
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      tmp = str.charAt(i) + "";
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      total = 1;
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      if (map.containsKey(tmp)) {
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        total = map.get(tmp)+1;
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      }
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      map.put(tmp, total);
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      if (maxToal<total) {
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        maxToal = total;
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        maxChar = tmp;
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      }
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    }
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    PrintUtill.printlnRule();
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    PrintUtill.println(map);
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    PrintUtill.println( "出现次数最多的字母是：" + maxChar + ",出现次数是：" + maxToal);
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  }
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  /**
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   * 通过String.split("")将字符串直接切割成字符串数组
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   * @param str
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   */
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  public static void count3(String str){
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    Map<String, Integer> map = new HashMap<String, Integer>();
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    int total = 0;
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    String[] myStrs = str.split("");
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    String tmp = null;
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    for (int i=0;i<myStrs.length; i++) {
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      tmp = myStrs[i];
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      total = 1;
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      if (map.containsKey(tmp)) {
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        total = map.get(tmp)+1;
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      }
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      map.put(tmp, total);
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    }
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    PrintUtill.printlnRule();
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    PrintUtill.println(map);
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  }
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  /**
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   * 通过String.toCharArray()将字符串转为char数组
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   * @param str
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   */
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  public static void count4(String str){
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    Map<String, Integer> map = new HashMap<String, Integer>();
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    int total = 0;
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    char[] myStrs = str.toCharArray();
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    String tmp = null;
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    for (int i=0;i<myStrs.length; i++) {
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      tmp = myStrs[i] + "";
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      total = 1;
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      if (map.containsKey(tmp)) {
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        total = map.get(tmp)+1;
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      }
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      map.put(tmp, total);
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    }
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    PrintUtill.printlnRule();
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    PrintUtill.println(map);
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  }