count the number of specific characters in a string java?

There are multiple way to count the number of specific characters in a string java. here we are count the character ‘h’ in the given string.

From toCharArray() and forloop() method:-

  • Create test method with int return type.
  • Declare a default count variable.
  • Convert String to character from str.toCharArray() method and store in ch[] array.
  • Iterate the character from for loop 0 to ch.length till.
  • Inside if condition, we compare the given character to character array index value.
  • If it return true then count and increment.
  • Now print the number of character value from i.

From java8 map and filter :-

  • First we convert string to intStream from chars() method.
  • From mapToObj() method we convert intStream data into Stream<Character>.
  • Inside filter we compare given character from input character ch value.
  • Now count the character from count() method.
  • Print number of character.
				
					public class CountCharDemo {
	public static void main(String[] args) {
		CountCharDemo cd = new CountCharDemo();
		String str = "how are you well here";
		// from toCharArray and for loop method
		int i = cd.test('h', str);
		System.out.println("total number of character from TocharArray :- " + i);

		// from java8 map and filter
		long count = str.chars().mapToObj(x -> (char) x).filter(ch -> ch == 'h').count();
		System.out.println("from java8 map and filter :- " + count);
	}

	public int test(char c, String str) {
		int count = 0;
		char ch[] = str.toCharArray();
		for (int i = 0; i < ch.length; i++) {
			if (c == ch[i]) {
				count++;
			}

		}
		return count;
	}
}

Output :-
total number of character from TocharArray :- 2
from java8 map and filter :- 2