Java Program to Count the number of occurrences of a char in a String?

Solution #1:

1. package com.javatutorial;
2.  
3. import java.util.Scanner;
4.  
5. public class CountNumberofChars {
6.  
7.  public static void main(String[] args) {
8.   
9.  String str = "";
10.  
11.  Scanner in= new Scanner(System.in);
12.  System.out.println("Please enter a String");
13.  
14.  str=in.nextLine();
15.  
16.  System.out.println("Please enter a Character");
17.  String chr=in.next();
18.  
19.  int charCount = str.length() - str.replaceAll("a", "").length();
20.  
21.  System.out.println("Number of occurances of given character:"+charCount);
22.  
23. }
24. 
    
25. }

Output:

1. Please enter a String
2. Java
3. Please enter a Character
4. a
5. Number of occurances of given character:2

Solution #2:

1. package com.javatutorial;
2.  
3. import java.util.Scanner;
4.  
5. public class CountNumberofChars {
6.   
7. public static int countOccurrences(String find, String string)
8. {
9. int count = 0;
10. int indexOf = 0;
11.  
12. while (indexOf > -1)
13. {
14.     indexOf = string.indexOf(find, indexOf + 1);
15.     if (indexOf > -1)
16.             count++;
17.       }
18. return count;
19.  }
20. 
    
21.  public static void main(String[] args) {
22.   
23.  int charCount=countOccurrences("a", "Instance of Java");
24.  
25.  System.out.println("Number of occurrences of given character:"+charCount);
26.  
27. }
28. 
    
29. }

Output:

1. Number of occurrences of given character: 3

Java experience interview programming questions on Strings