Checking Anagram of a String array input

Question

This is my code below to check anagram of a given string array.
It always gives me false even in the simplest case with only one input.
I don't understand am I not converting string array into string correctly or my algorithm is plain wrong.

public class anagram
{
     static boolean isAnagram(String[] s1, String[] s2) { 
        String str = s1.toString();
        String str2 = s2.toString();
        if (str.length() != str2.length()) 
            return false;

        for (int i =0; i<str.length();i++)
        { 
            for (int j = 0;j<str2.length();j++)
            { 
                if (s1[i] == s2[j]) {
                    return true; 
                }
                return false; 
            }                   
        } 
        return true; 
    }

    public static void main(String [] args){
        String [] s1 = {"shot"};
        String [] s2 = {"host"};
        System.out.println(isAnagram(s1,s2));
    }
}

Can you please help me identify what is wrong?

And why is my question downvoted? What rules I didn't abide by so that I make sure I don't do that again? — zydexo, Dec 10 '14 at 04:36

score 0 · Answer 1 · edited May 23 '17 at 12:24

0

Strings are not primitive variables in Java, therefore you must use the .equals() method instead of checking for equality using '==' to perform a thorough comparison.

edited May 23 '17 at 12:24

Community

1
1

answered Dec 10 '14 at 04:05

Mapsy

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It still gives me false. I'm sorry i'm asking some basic questions. – zydexo Dec 10 '14 at 04:24

almightyGOSU · Accepted Answer · 2014-12-10T04:38:00.617

Your algorithm for checking seems to be a little incorrect.
Edited the isAnagram function here:

public static void main(String[] args)
{
    String s1 = "shotaabb";
    String s2 = "hostbaba";
    System.out.printf("String s1: %s, String s2: %s%n", s1, s2);
    System.out.println(isAnagram(s1, s2) ?
            "Is anagram" : "Is not an anagram");
}

static boolean isAnagram(String s1, String s2)
{
    String str1 = new String(s1);
    String str2 = new String(s2);

    // Ensures that both strings are of the same length
    if (str1.length() != str2.length())
        return false;

    int str1Len = str1.length();
    for (int i = 0; i < str1Len; i++)
    {
        int charIndex = str2.indexOf(str1.charAt(i));

        if(charIndex == -1) // Not found in str2
            return false;
        else
        {
            // Remove the character from str2
            str2 = str2.substring(0, charIndex) +
                str2.substring(charIndex + 1);
        }
    }

    return true;
}

What the code does is:

Gets a character from s1, finds the index of that character inside s2
If the index is -1, character not found inside s2, return false
If the character can be found inside s2, remove it from s2
At the end, if all characters inside s1 can be found in s2, return true
Based on the fact that both strings are of the same length, if all character in s1 can be found & removed from s2, s1 is an anagram of s2 & vice versa.

Output:

String s1: shotaabb, String s2: hostbaba
Is anagram

Update (Comparing String arrays):

String[] strArr1 = {"shot", "dcba"};
String[] strArr2 = {"host", "abcd"};

for(String s1 : strArr1)
{
    for(String s2 : strArr2)
    {
        System.out.printf("%nString s1: %s, String s2: %s%n", s1, s2);
        System.out.println(isAnagram(s1, s2) ?
            "Is anagram" : "Is not an anagram");
    }
}

Output for updated code:

String s1: shot, String s2: host
Is anagram

String s1: shot, String s2: abcd
Is not an anagram

String s1: dcba, String s2: host
Is not an anagram

String s1: dcba, String s2: abcd
Is anagram

I appreciate that! but what if my input is String Array as mentioned above and not a string. — zydexo, Dec 10 '14 at 04:26
Why would you compare 2 String array instead of 2 strings? I don't really get that. — almightyGOSU, Dec 10 '14 at 04:27
It was given to me, i don't know maybe to make my life more stressful. — zydexo, Dec 10 '14 at 04:31
That's interesting! Thanks for the help! Just for my curiosity, what do we do when isAnagram() has a string array input? How do we solve it then? convert string array to string there? — zydexo, Dec 10 '14 at 04:48
If `isAnagram()` only returns a boolean, I don't think it will be of much use to pass in 2 String arrays? It will depend a lot on what you are trying to achieve with `isAnagram()` in my opinion. — almightyGOSU, Dec 10 '14 at 05:13

score 0 · Answer 3 · edited Feb 04 '17 at 20:41

public static bool IsAnagram(string firstString, string secondString)
{
    firstString = firstString.Replace(" ", "").ToLower();
    secondString = secondString.Replace(" ", "").ToLower();

    var firstStringArray = firstString.OrderBy(x => x);
    var secondStringArray = secondString.OrderBy(x => x);

    string s1 = new string(firstStringArray.ToArray());
    string s2 = new string(secondStringArray.ToArray());

    if (s1.Equals(s2))
    {
        return true;
    } else {
        return false;
    }          
}

score 0 · Answer 4 · answered Feb 05 '17 at 22:54

To check if two String are anagram, case not sensitive, here the method:

public boolean isAnagram(String s1, String s2) {
    class SortChars{
        String sort(String source) {
            char[] chars = source.toLowerCase().toCharArray();
            Arrays.sort(chars);
            return new String(chars);
        }
    }
    SortChars sc = new SortChars();
    return sc.sort(s1).equals(sc.sort(s2));
}

The solution is taken from the book "cracking the coding interview", Authored by Gayle Laakmann McDowell

Checking Anagram of a String array input

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