统计字符串中每个字符出现的次数

一.使用java style，使用map的特性来写

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

public class CharacterStatisticsA {
public static void main(String[] args) {
Scanner cin = new Scanner(System.in);
String str = cin.nextLine();
Map<Character, Integer> map = new HashMap<>();
for(int i =0;i<str.length();i++) {
char c = str.charAt(i);
if(map.containsKey(c)) {
map.put(c, map.get(c)+1);
}else {
map.put(c, 1);
}
}System.out.println(map);
}

}

二.技巧性的写法

import java.util.Scanner;
public class CharacterStatistics {
public static void main(String[] args) {
Scanner cin = new Scanner(System.in);
String str = cin.nextLine();
int length = 0;
while(str.length()>0){
String first = String.valueOf(str.charAt(0));
String newString = str.replaceAll(first, "");
length = str.length()-newString.length();
str = newString;
System.out.println(first +":"+ length+" ");
}
}
}