Stream count() method in Java with examples

Count occurrence of a given character in a string using Stream API in Java

Last Updated : 29 May, 2019

Given a string and a character, the task is to make a function which counts the occurrence of the given character in the string using Stream API. Examples:

Input: str = "geeksforgeeks", c = 'e'
Output: 4
'e' appears four times in str.

Input: str = "abccdefgaa", c = 'a' 
Output: 3
'a' appears three times in str.

Approach:

Convert the string into character stream
Check if the character in the stream is the character to be counted using filter() function.
Count the matched characters using the count() function

Below is the implementation of the above approach:

Java

// Java program to count occurrences
// of a character using Stream

import java.util.stream.*;

class GFG {

    // Method that returns the count of the given
    // character in the string
    public static long count(String s, char ch)
    {

        return s.chars()
            .filter(c -> c == ch)
            .count();
    }

    // Driver method
    public static void main(String args[])
    {
        String str = "geeksforgeeks";
        char c = 'e';
        System.out.println(count(str, c));
    }
}

Output:

Related Article: Program to count occurrence of a given character in a string

Stream count() method in Java with examples

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