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Check whether two Strings are Anagram of each other using HashMap in Java

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  • Difficulty Level : Basic
  • Last Updated : 24 Jul, 2022

Write a function to check whether two given strings are an Anagram of each other or not. An anagram of a string is another string that contains the same characters, only the order of characters can be different.

For example, “abcd” and “dabc” are an Anagram of each other.

check-whether-two-strings-are-anagram-of-each-other

Approach: Hashmaps can also be used to find if any two given strings are anagrams or not, by mapping the characters of each string to individual hashmaps and comparing them together. Implementation: 

Java




// Java code to check whether two strings
// are Anagram or not using HashMap
 
import java.io.*;
import java.util.*;
 
class GFG {
 
    // Function to check whether two strings
    // are an anagram of each other
    static boolean areAnagram(String str1, String str2)
    {
 
        HashMap<Character, Integer> hmap1
            = new HashMap<Character, Integer>();
        HashMap<Character, Integer> hmap2
            = new HashMap<Character, Integer>();
 
        char arr1[] = str1.toCharArray();
        char arr2[] = str2.toCharArray();
 
        // Mapping first string
        for (int i = 0; i < arr1.length; i++) {
 
            if (hmap1.get(arr1[i]) == null) {
 
                hmap1.put(arr1[i], 1);
            }
            else {
                Integer c = (int)hmap1.get(arr1[i]);
                hmap1.put(arr1[i], ++c);
            }
        }
 
        // Mapping second String
        for (int j = 0; j < arr2.length; j++) {
 
            if (hmap2.get(arr2[j]) == null)
                hmap2.put(arr2[j], 1);
            else {
 
                Integer d = (int)hmap2.get(arr2[j]);
                hmap2.put(arr2[j], ++d);
            }
        }
 
        if (hmap1.equals(hmap2))
            return true;
        else
            return false;
    }
 
    // Test function
    public static void test(String str1, String str2)
    {
 
        System.out.println("Strings to be checked are:\n"
                        + str1 + "\n" + str2 + "\n");
 
        // Find the result
        if (areAnagram(str1, str2))
            System.out.println("The two strings are "
                            + "anagrams of each other\n");
        else
            System.out.println("The two strings are not"
                            + " anagrams of each other\n");
    }
 
    // Driver program
    public static void main(String args[])
    {
 
        // Get the Strings
        String str1 = "geeksforgeeks";
        String str2 = "forgeeksgeeks";
 
        // Test the Strings
        test(str1, str2);
 
        // Get the Strings
        str1 = "geeksforgeeks";
        str2 = "geeks";
 
        // Test the Strings
        test(str1, str2);
    }
}

Output:

Strings to be checked are:
geeksforgeeks
forgeeksgeeks

The two strings are anagrams of each other

Strings to be checked are:
geeksforgeeks
geeks

The two strings are not anagram of each other

Time Complexity: O(l1 + l2) where l1 and l2 are lengths of strings.

Auxiliary space: O(m1 + m2) where m1 and m2 are numbers of unique characters in each string.

Please suggest if someone has a better solution which is more efficient in terms of space and time.
This article is contributed by Aarti_Rathi. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above

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