JAVA统计字符串中某个字符出现的次数

在JAVA中统计字符串某个字符出现的次数，可以循环使用String的charAt(int index)函数。

public class Test {

	public static void main(String[] args) {
	
		String s1 = "xyyx";
		//String s2 = "abe";
		int s1xCount = 0;
		int s1yCount = 0;
		
		for(int i = 0; i < s1.length(); i++) {
			if(s1.charAt(i) == 'x') {
				s1xCount++;
			}
			else {
				if(s1.charAt(i) == 'y') {
					s1yCount++;
				}
			}
		}
		System.out.println("s1.length: " + s1.length());
		System.out.println("x count in s1: " + s1xCount);
		System.out.println("y count in s1: " + s1yCount);
	}

}

输出结果：