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Java Program To Check Whether Two Strings Are Anagram Of Each Other

  • Last Updated : 23 Dec, 2021

Write a function to check whether two given strings are 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

We strongly recommend that you click here and practice it, before moving on to the solution.

Method 1 (Use Sorting):

  1. Sort both strings
  2. Compare the sorted strings

Below is the implementation of the above idea:

Java




// Java program to check whether two strings
// are anagrams of each other
import java.io.*;
import java.util.Arrays;
import java.util.Collections;
class GFG
{
    /* Function to check whether two strings
       are anagram of each other */
    static boolean areAnagram(char[] str1,
                              char[] str2)
    {
        // Get lengths of both strings
        int n1 = str1.length;
        int n2 = str2.length;
 
        // If length of both strings is not
        // same, then they cannot be anagram
        if (n1 != n2)
            return false;
 
        // Sort both strings
        Arrays.sort(str1);
        Arrays.sort(str2);
 
        // Compare sorted strings
        for (int i = 0; i < n1; i++)
            if (str1[i] != str2[i])
                return false;
 
        return true;
    }
 
    // Driver Code
    public static void main(String args[])
    {
        char str1[] = {'t', 'e', 's', 't'};
        char str2[] = {'t', 't', 'e', 'w'};
       
        // Function Call
        if (areAnagram(str1, str2))
            System.out.println(
            "The two strings are" +
            " anagram of each other");
        else
            System.out.println(
            "The two strings are not" +
            " anagram of each other");
    }
}
// This code is contributed by Nikita Tiwari.

 Output:

The two strings are not anagram of each other

Time Complexity: O(nLogn)

Method 2 (Count characters): 
This method assumes that the set of possible characters in both strings is small. In the following implementation, it is assumed that the characters are stored using 8 bit and there can be 256 possible characters. 

  1. Create count arrays of size 256 for both strings. Initialize all values in count arrays as 0.
  2. Iterate through every character of both strings and increment the count of character in the corresponding count arrays.
  3. Compare count arrays. If both count arrays are same, then return true.

Below is the implementation of the above idea:

Java




// Java program to check if two strings
// are anagrams of each other
import java.io.*;
import java.util.*;
class GFG
{
    static int NO_OF_CHARS = 256;
 
    /* Function to check whether two strings
       are anagram of each other */
    static boolean areAnagram(char str1[],
                              char str2[])
    {
        // Create 2 count arrays and initialize
        // all values as 0
        int count1[] = new int[NO_OF_CHARS];
        Arrays.fill(count1, 0);
        int count2[] = new int[NO_OF_CHARS];
        Arrays.fill(count2, 0);
        int i;
 
        // For each character in input strings,
        // increment count in the corresponding
        // count array
        for (i = 0; i < str1.length &&
             i < str2.length; i++)
        {
            count1[str1[i]]++;
            count2[str2[i]]++;
        }
 
        // If both strings are of different length.
        // Removing this condition will make the
        // program fail for strings like "aaca"
        // and "aca"
        if (str1.length != str2.length)
            return false;
 
        // Compare count arrays
        for (i = 0; i < NO_OF_CHARS; i++)
            if (count1[i] != count2[i])
                return false;
 
        return true;
    }
 
    // Driver code
    public static void main(String args[])
    {
        char str1[] =
        ("geeksforgeeks").toCharArray();
        char str2[] =
        ("forgeeksgeeks").toCharArray();
 
        // Function call
        if (areAnagram(str1, str2))
            System.out.println(
            "The two strings are" +
            "anagram of each other");
        else
            System.out.println(
            "The two strings are not" +
            " anagram of each other");
    }
}
// This code is contributed by Nikita Tiwari.

 Output:

The two strings are anagram of each other

Method 3 (count characters using one array): 
The above implementation can be further to use only one count array instead of two. We can increment the value in count array for characters in str1 and decrement for characters in str2. Finally, if all count values are 0, then the two strings are anagram of each other. Thanks to Ace for suggesting this optimization. 

Java




// Java program to check if two strings
// are anagrams of each other
class GFG{
 
static int NO_OF_CHARS = 256;
 
// Function to check if two strings
// are anagrams of each other
static boolean areAnagram(char[] str1,
                          char[] str2)
{  
    // Create a count array and initialize
    // all values as 0
    int[] count = new int[NO_OF_CHARS];
    int i;
 
    // For each character in input strings,
    // increment count in the corresponding
    // count array
    for(i = 0; i < str1.length; i++)
    {
        count[str1[i] - 'a']++;
        count[str2[i] - 'a']--;
    }
 
    // If both strings are of different
    // length. Removing this condition
    // will make the program fail for
    // strings like "aaca" and "aca"
    if (str1.length != str2.length)
        return false;
 
    // See if there is any non-zero
    // value in count array
    for(i = 0; i < NO_OF_CHARS; i++)
        if (count[i] != 0)
        {
            return false;
        }
    return true;
}
 
// Driver code
public static void main(String[] args)
{
    char str1[] =
    "geeksforgeeks".toCharArray();
    char str2[] =
    "forgeeksgeeks".toCharArray();
 
    // Function call
    if (areAnagram(str1, str2))
        System.out.print(
        "The two strings are " +
        "anagram of each other");
    else
        System.out.print(
        "The two strings are " +
        "not anagram of each other");
}
}
// This code is contributed by mark_85

Output:

The two strings are anagram of each other

Time Complexity: O(n)
Please refer complete article on Check whether two strings are anagram of each other for more details!


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