Comparing two arrays of Strings

Question

I am a beginner in Java. I need to compare two arrays of string and find out if any value from the first array matches any value in second array?

Here is my function which does not work as expected,

public static boolean CheckStatAppearinLeftAndRight1(String[] array1, String[] array2)
{
    boolean b = false;
    for (int i = 0; i < array2.length; i++) 
    {
        for (int a = 0; a < array1.length; a++)
        {
            if (array2[i] == array1[a])
            {
                b = true;
                break;
            }
            else
            {
                b = false;
            }
        }
   }
   return b;
}

Can someone please point out the issue here?

ignorance is not a mistake ;), its very common mistake anybody does, i believe. — Satheesh Cheveri, Dec 11 '13 at 05:55
In Java, you don't compare Strings with `==`; use `.equals()` or `.compareTo()` — Barranka, Dec 11 '13 at 05:55

score 1 · Answer 1 · answered Dec 11 '13 at 05:49

1

if (array2[i] == array1[a])

should be

if ((array2[i]).equals(array1[a]))

answered Dec 11 '13 at 05:49

Hussain Akhtar Wahid 'Ghouri'

6,527
8
50
85

Is there any big reason why you surround `array2[i]` with parentheses? – Justin Dec 11 '13 at 06:03
1

just bto be clear about application of equals method – Hussain Akhtar Wahid 'Ghouri' Dec 11 '13 at 06:04

score 0 · Answer 2 · answered Dec 11 '13 at 05:53

try>>>

import java.util.Arrays;

public class Main {
   public static void main(String[] args) throws Exception {
      int[] ary = {1,2,3,4,5,6};
      int[] ary1 = {1,2,3,4,5,6};
      int[] ary2 = {1,2,3,4};
      System.out.println("Is array 1 equal to array 2?? "
      +Arrays.equals(ary, ary1));
      System.out.println("Is array 1 equal to array 3?? "
      +Arrays.equals(ary, ary2));
   }
}

score 0 · Answer 3 · answered Dec 11 '13 at 05:53

0

Use array2[i].equals(array1[i]) instead of using == operator. == operator compares the two references and would give you false. equals() method is already overriden in class String which matches the exact characters from two different String Objects.

answered Dec 11 '13 at 05:53

Nishant Lakhara

2,295
4
23
46

score -1 · Answer 4 · answered Dec 11 '13 at 05:54

    boolean b = false;
    for (int i = 0; i < array2.length; i++) 
    {

        for (int a = 0; a < array1.length; a++)
        {

            if (array2[i].equals(array1[a]))
            {
                b = true;
                break;
            }
            else
            {
                b = false;

            }
        }
        if(b)
            return b;
    }
}

Comparing two arrays of Strings

4 Answers4