By | 16.03.2017

# Java Program to Count frequency of each characters using Buffered Reader

Write a Java Program to Count frequency or occurrence of each characters using Buffered Reader.Finding characters frequency of a String means calculating the occurrence of  each alphabet present in the string.

Since there’s no pre-build function present in Java for calculating the occurrence of the characters or alphabets so, we have to write a program which will give the frequency of characters present in the string.

Let’s get started :

• Firstly, the program will ask for an input string from the user.
• Then start searching for the occurrence of all the characters present inside the string to find the frequency of all the characters in the string.
• Then, Display the frequency of all the characters on the output screen as shown in the following program.

For example :

• If the user has entered – “Codezclub” .
• Then the program will give –

==========================

Alphabet    Frequency

==========================

b                     1
c                     2
d                     1
e                     1
l                      1
o                     1
u                     1
z                      1

## ALGORITHM :

1. Start

2. Accept a sentence from the user.

3. Extract a character.

4. Count the no. of times it occurs in the sentence.

5. Print its frequency.

6. Repeat Steps 3 to 6 till all the frequencies are printed.

7. End

Following Java Program ask to the user to enter a string to find the frequency of all the characters present in the string and display the frequency of all the characters one by one on the screen.

Below is the source code for Java Program to Count frequency or occurrence of all characters in string which is successfully compiled and run on Windows System to produce desired output as shown below :

## SOURCE CODE : :

```import java.io.*;
public class Count_Frequency
{
public static void main(String args[])throws IOException
{
System.out.print("Enter any string : ");

s=s.toLowerCase(); //converting the string into lowercase
int l=s.length(); //finding the length of the string

char ch;
System.out.println("Output:");
System.out.println("=========================="); //this is just for styling the look of the output
System.out.println("Alphabet\tFrequency");
System.out.println("==========================");

/* Counting frequency of alphabets begins below */
int count=0;
for(char i='a'; i<='z'; i++)
{
count = 0;
for(int j=0; j<l; j++)
{
ch=s.charAt(j); //extracting characters of the string one by one
if(ch==i) //first checking the whole string for 'a', then 'b' and so on
count++; //increasing count of those aplhabets which are present in the string
}
if(count!=0)//printing only those alphabets whose count is not '0'
{
System.out.println(i+"\t\t"+count);
}
}
}
}```

## OUTPUT: :

```Enter any string : zazaarrtewsdeddsazsa
Output:
==========================
Alphabet        Frequency
==========================
a               5
d               3
e               2
r               2
s               3
t               1
w               1
z               3```