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# How to count the occurrences of each character in Java

In this shot, we will learn how to count the occurrences of each character in a string using Java.

Let’s begin by defining the problem statement and looking at an example.

### Problem

Write a Java program that will print the number of occurrences of each character in a string.

#### Example

• Input

This is an example

• Output

Occurrences of p = 1

Occurrences of a = 2

Occurrences of s = 2

Occurrences of T = 1

Occurrences of e = 2

Occurrences of h = 1

Occurrences of x = 1

Occurrences of i = 2

Occurrences of l = 1

Occurrences of m = 1

Occurrences of n = 1

### Solution

We will solve this problem using Java HashMap.

• Declare a hashmap that has a key of type Character and value of type Integer.

• Convert string to a character array.

• Traverse every character, and check if it has been added to the hashmap or not.

• If it is has been added to the hashmap, increment the count of that character in hashmap.
• If it has not been added to the hashmap, then save it in the hashmap with the value set as 1.
• Now, print the hashmap.

### Code

import java.io.*;
import java.util.*;

class Solution {
public static void main( String args[] ) {
//given string
String str = "This is an example";

//declare hashmap
HashMap<Character, Integer> count = new HashMap<Character, Integer>();

//convert string to character array
char[] arr = str.toCharArray();

//traverse every character and count the Occurrences
for(char c:arr){

//filter out white spaces
if(c != ' '){
if(count.containsKey(c)){
//if character already traversed, increment it
count.put(c, count.get(c) + 1);
}else{
//if character not traversed, add it to hashmap
count.put(c,1);
}
}

}

//traverse the map and print the number of occurences of a character
for(Map.Entry entry : count.entrySet()){
System.out.println("Occurrences of " + entry.getKey() + " = " + entry.getValue());
}
}
}

### Explanation

In the example above:

• In line 7, the given string str has the value This is an example.

• In line 10, we declare a hashmap count, which has the key of type Character and value of type Integer. It stores the character in key and the count of that character in value.

• In line 13, we convert the string str to character array arr.

• In line 16, we traverse every character in the character array arr.

• In line 19, where we filter out the white spaces in the string, it will check if the present character c is not a white space, then it executes the inner if condition.
• In lines 20 to 25, we check if the present character c is added to the hashmap or not. If it is added, increment the value of that character in the hashmap. If it is not added, then add character c to hashmap with value 1.
• In lines 32 to 34, after traversing every character in arr, hashmap count is filled with occurrences of characters. We then print them one by one.

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