Java - count character occurrences

In this article, we would like to show you how to count occurrences of a character in a String in Java.

Quick solution:

String text = "ABC";
char character = 'A';
int result = 0;

for (int i = 0; i < text.length(); i++) {
    if (text.charAt(i) == character) {
        result++;
    }
}

System.out.println(result); // 1

1. Using simple for loop

In this example, we create simple for loop to iterate through the string and check if each character matches the character we want.

public class Example {

    public static void main(String[] args) {
        String text = "ABA";
        char character = 'A';
        int result = 0;

        for (int i = 0; i < text.length(); i++) {
            if (text.charAt(i) == character) {
                result++;
            }
        }
        
        System.out.println("result = " + result); // 2
    }
}

Output:

result = 2

2. Using String replace()

In this example, we use String replace() method with string length subtraction to count the occurrences of the A character in the text.

public class Example {

    public static void main(String[] args) {
        String text = "ABA";
        int result = text.length() - text.replace("A", "").length();

        System.out.println("result = " + result);  // 2
    }
}

Output:

result = 2

3. Using String replaceAll()

In this example, we use String replace() method with [^A] regex to count the occurrences of the A character in the text.

Regex explanation:

• [^ ] is the negation operator, negated set (matches any character that is not in the set),
• [^A] matches any character except A.

Practical example:

public class Example {

    public static void main(String[] args) {
        String text = "ABA";
        int result = text.replaceAll("[^A]", "").length();

        System.out.println("result = " + result);  // 2
    }
}

Output:

result = 2

4. Using String split()

In this example, we use String split() method with string length() to count the occurrences of the A character in the text.

public class Example {

    public static void main(String[] args) {
        String text = "ABA";
        int result = text.split("A", -1).length - 1;

        System.out.println("result = " + result);  // 2
    }
}

Output:

result = 2