[JAVA] 문자열에서 특정 문자의 개수 세기

1. 반복문 이용하기

public class CharCountTest {

	public static void main(String[] args) {

		String str = "soultree";

		System.out.println(countChar(str, 's')); //1
		System.out.println(countChar(str, 'o')); //1
		System.out.println(countChar(str, 'u')); //1
		System.out.println(countChar(str, 'l')); //1
		System.out.println(countChar(str, 't')); //1
		System.out.println(countChar(str, 'r')); //1
		System.out.println(countChar(str, 'e')); //2
	}

	public static int countChar(String str, char ch) {
		int count = 0;

		for (int i = 0; i < str.length(); i++) {
			if (str.charAt(i) == ch) {
				count++;
			}
		}

		return count;
	}
}

 

2. replace() 이용하기

public class CharCountTest {

	public static void main(String[] args) {

		String str = "soultree";

		System.out.println(countChar(str, 's')); //1
		System.out.println(countChar(str, 'o')); //1
		System.out.println(countChar(str, 'u')); //1
		System.out.println(countChar(str, 'l')); //1
		System.out.println(countChar(str, 't')); //1
		System.out.println(countChar(str, 'r')); //1
		System.out.println(countChar(str, 'e')); //2
	}

	public static int countChar(String str, char ch) {
		
		return str.length() - str.replace(String.valueOf(ch), "").length();
	

	}
}