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home / developersection / forums / write a java program to get distinct characters and their count in a string.
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Ashutosh Patel
Ashutosh Patel

Jr. Software Developer

I am a software developer at MindStick soft. Pvt. ltd. I joined this company in august 2021 after completing my post-graduation course. I love to see the historical places of my country.

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2 Answers

Aryan Kumar
Aryan Kumar 28 Apr 2023
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Here's an example Java program that gets the distinct characters and their count in a string:

import java.util.HashMap;
import java.util.Map;
public class DistinctCharactersCount {
   public static void main(String[] args) {
       String str = "Hello, World!";
       Map<Character, Integer> charCountMap = new HashMap<>();
       // Iterate through each character in the string
       for (int i = 0; i < str.length(); i++) {
           char c = str.charAt(i);
           // If the character is already in the map, increment its count
           if (charCountMap.containsKey(c)) {
               charCountMap.put(c, charCountMap.get(c) + 1);
           }
           // Otherwise, add the character to the map with a count of 1
           else {
               charCountMap.put(c, 1);
           }
       }
       // Print the distinct characters and their count
       System.out.println("Distinct characters in the string '" + str + "':");
       for (Map.Entry<Character, Integer> entry : charCountMap.entrySet()) {
           System.out.println("'" + entry.getKey() + "' : " + entry.getValue());
       }
   }
}

In this example, we first define a string called str that we want to count the distinct characters in. We then create a HashMap called charCountMap to store the count of each distinct character in the string.

Next, we iterate through each character in the string using a for loop. For each character, we check if it already exists in the charCountMap. If it does, we increment its count by 1. If it doesn't, we add the character to the map with a count of 1.

Finally, we print out the distinct characters and their count using a for-each loop to iterate over the entries in the charCountMap.

Krishnapriya Rajeev
Krishnapriya Rajeev 24 Mar 2023
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The code given below finds all the distinct characters and their count in a string using Java:

public class trial 
{  
    public static void main(String args[])  
    {  
        String str = "Welcome to MindStick";	// Declaration and initialization of string
        int MAX = 256;		// Maximum number of possible characters
        int count[] = new int[MAX];		// Stores count of each character
 
        int len = str.length();  
 
        for (int i = 0; i < len; i++)  
         count[str.charAt(i)]++;	// Increments count of each character by 1

        char ch[] = new char[str.length()];
      
        for (int i = 0; i < len; i++)   
        {     
            ch[i] = str.charAt(i);  
            int find = 0;  
            for (int j = 0; j <= i; j++)   
            {  
                if (str.charAt(i) == ch[j])  
                find++;  
            }             
            if (find == 1)		// If first occurence of character
            System.out.println("The frequency of "+ str.charAt(i)+ " is: " + count[str.charAt(i)]);
        }  
    }  
}
OUTPUT:
The frequency of W is: 1
The frequency of e is: 2
The frequency of l is: 1
The frequency of c is: 2
The frequency of o is: 2
The frequency of m is: 1
The frequency of   is: 2
The frequency of t is: 2
The frequency of M is: 1
The frequency of i is: 2
The frequency of n is: 1
The frequency of d is: 1
The frequency of S is: 1
The frequency of k is: 1
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