java 怎样从一个string字符串中判断某个字母出现的次数

Answer 1

/** 计算字符串某个字符个数
* @param str 原字符串
* @param ch 计算的字符
* @return */
public static int getCharCount(String str, char ch) {
if (str == null) {
return 0;
}
int count = 0;
char[] chars = str.toCharArray();
for (char c : chars) {
if (ch == c) {
count++;
}
}
return count;
}

Answer 2

public static void main(String[] args) {
String data = "abcdsldijsCdsdfs";
String str = "c";
System.out.println(findCount(data,str));
System.out.println(findCountNotCheck(data,str));
}
//区分大小写
public static int findCount(String data,String str){
return data.split(str).length-1;
}
//不区分大小写
public static int findCountNotCheck(String data,String str){
return data.toUpperCase().split(str.toUpperCase()).length-1;
}

Answer 3

substring()方法，看看出现了几个数组-1

Answer 4

var result=from i in str.ToUpper()
where i=='C'
select i;