Java Program to Count frequency of each characters using Buffered Reader

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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.

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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

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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

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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 :

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SOURCE CODE : :

import java.io.*;
public class Count_Frequency
{
    public static void main(String args[])throws IOException
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        System.out.print("Enter any string : ");
        String s = br.readLine();
  
        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);
                }
            }
    }
}

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OUTPUT: :

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

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