Java program: find the frequency of the given character in a string

In this article, we will discuss the concept of the Java program: find the frequency of the given character in a string

In this post, we are going to learn how to find the frequency of the given character in the string in Java programming language

Code to find the frequency of the given character in the string

find the frequency of the given character in the string using for loop

The program allows the user to enter a String and a character and then it finds the frequency of the given character in the string using for loop in Java programing language

program 1

//program to count vowel,consonant,digit,special character and space
import java.util.Scanner;
public class FindFrequencyOfChar{
public static void main(String args[]){
//variable declaration 
    String str;
    char ch;
    int frequency=0;
//vriable declaration and initialization
 Scanner scan=new Scanner(System.in); 
    //create a scanner object for input
    
System.out.println("Enter the String  ");
str=scan.nextLine();
System.out.println("Enter the Character  ");
ch=scan.nextLine().charAt(0);

for(int i=0; i<str.length(); i++){

if(ch==str.charAt(i)){ //check frequancy of the given character
    frequency++;
}
}
System.out.println("Frequency of "+ch+" = "+frequency); // display frequency of the given character
}
}

When the above code is executed, it produces the following result

Enter the string
Java language
Enter the character
a
Frequency of a=4

find the frequency of the given character in the string using while loop

The program allows the user to enter a String and a character then it finds the frequency of the given character in the string using while loop in Java programing language

program 2

import java.util.Scanner;
public class FindFrequencyOfChar1{
public static void main(String args[]){
//variable declaration 
    String str;
    char ch;
    int frequency=0;
//vriable declaration and initialization
 Scanner scan=new Scanner(System.in); 
    //create a scanner object for input
    
System.out.println("Enter the String  ");
str=scan.nextLine();
System.out.println("Enter the Character  ");
ch=scan.nextLine().charAt(0);

int i=0;
while(i<str.length()){

if(ch==str.charAt(i)){ //check frequency of a character
    frequency++;
}
 i++;
}
System.out.println("Frequency of "+ch+" = "+frequency);
}// display frequency of a character
}

When the above code is executed, it produces the following result

Enter the string
Java programming language
Enter the character
g
Frequency of g=4

find the frequency of the given character in the string using do-while loop

The program allows the user to enter a String and a character and then it finds the frequency of the given character in a string using do-while loop in Java programing language

program 3

import java.util.Scanner;
public class FindFrequencyOfChar2{
public static void main(String args[]){
//variable declaration 
    String str;
    char ch;
    int frequency=0;
//vriable declaration and initialization
 Scanner scan=new Scanner(System.in); 
    //create a scanner object for input
    
System.out.println("Enter the String  ");
str=scan.nextLine();
System.out.println("Enter the Character  ");
ch=scan.nextLine().charAt(0);

int i=0;
do{

if(ch==str.charAt(i)){ //check frequency of a character
    frequency++;
}
 i++;
}while(i<str.length());
System.out.println("Frequency of "+ch+" = "+frequency);
}//display frequency of the given character
}

When the above code is executed, it produces the following result

Enter the string
code for coding
Enter the character
o
Frequency of o=3

Approaches

Declare a String variable as String str, char ch;
Declare and initialize integer variables as frequency=0;
The user asked to enter a string
The given string is stored in the variable str;
The user asked to enter a character
The given character is stored in the variable ch;
A loop(for, while and do-while) is used to count frequency of the character in the given string.
It is initialized as i=0, checks the condition whether i<str.length(); and executes the loop until the given condition becomes true
Use an if condition to test if(ch==str.charAt(i)), when the if statements is true, The frequency becomes frequency + 1( frequency = frequency +1);
When it is false, terminates the loop
Finally, the program displays the frequency of the given character of the given string