Java中得出字符串中每个字符串出现的次数

来源：互联网发布：win10网络凭据是什么编辑：程序博客网时间：2024/06/08 18:19

 1、使用HaspMap的键值来存储“字符”及“字符次数”:

   String str = "1122345678";HashMap<Character, Integer> strhash = new HashMap<Character, Integer>();int num = 0;int count = 0;for (int i = 0; i <= str.length() - 1; i++) {char c = str.charAt(i);int temp = 0;for (int j = 0; j <= str.length() - 1; j++) {num = str.indexOf(c, temp);if (num != -1) {count++;temp = num + 1;continue; } else {strhash.put(c, count);count = 0;break;}}} /*Iterator iter = strhash.entrySet().iterator();// 返回一个set集合while (iter.hasNext()) {Map.Entry<Character, Integer> entry = (Map.Entry<Character, Integer>) iter.next();Object key = entry.getKey();Object value = entry.getValue();System.out.println(key + "=" + value);} */Iterator iter1 = strhash.keySet().iterator();while (iter1.hasNext()) {Object key = iter1.next();Object value = strhash.get(key);System.err.println(key + "=" + value);}

2、把字符中每个字符先取出来(使用递归的方式)，然后循环查询次数,效率上比第一种差,但是好理解。

public class Test {  char array_char[];  List lists=new ArrayList(); public int getInstances(String all, String choice) {   int total=0;   array_char=all.toCharArray();   for(int i=0;i<array_char.length;i++){   if (array_char[i]==(choice.charAt(0))){   total++;   }   }   return total;  } 
 public static void main(String[] args) {     Test test=new Test();       String str="144745741258444174584";     List array=test.result(str);    for(int i=0;i<array.size();i++)    {     System.out.println(array.get(i)+"  出现的次数："+test.getInstances(str, array.get(i).toString()));    }  }  public List result(String str) {   String st="";  if(str.length()>0)  {   lists.add(str.substring(0,1));       st=str.replaceAll(str.substring(0,1),"");   result(st);  }  return lists; } }