How do I count the number of occurrences of a char in a String?
Category: java.lang, viewed: 981 time(s).
This example show you how to count the number of a character occurrences in a string. We show two ways to do it, using the String.replaceAll(String regex, String replace) method and creating a loop that check every char in the String and count the matched char.
package org.kodejava.example.lang;
public class CharCounter {
public static void main(String[] args) {
String text = "a,b,c,c,e,f,g,g,g,g,h";
//
// Use the CharCounter.countCharOccurrences() method to count.
//
int numberOfLetterC = CharCounter.countCharOccurrences(text, 'c');
System.out.println("Letter c = " + numberOfLetterC);
//
// Other solution is to use the String.replaceAll() method. We'll
// replace the chars other than the counted char with an empty string.
// To get the char occurrences we count the lenght of the remaining
// string.
//
int numberOfComma = text.replaceAll("[^,]", "").length();
System.out.println("Comma = " + numberOfComma);
int numberOfLetterG = text.replaceAll("[^g]", "").length();
System.out.println("Letter g = " + numberOfLetterG);
}
/**
* Count number of specified char occurrences in the specified string.
*/
public static int countCharOccurrences(String source, char target) {
int counter = 0;
//
// Loop through the string and increment the counter if the
// target character found in the string.
//
for (int i = 0; i < source.length(); i++) {
if (source.charAt(i) == target) {
counter++;
}
}
return counter;
}
}
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