Finding a Needle in a Haystack in Java

The challenge

Can you find the needle in the haystack?

Write a function findNeedle() that takes an array full of junk but containing one "needle"

After your function finds the needle it should return a message (as a string) that says:

"found the needle at position " plus the index it found the needle, so:

findNeedle(new Object[] {"hay", "junk", "hay", "hay", "moreJunk", "needle", "randomJunk"})

should return "found the needle at position 5"

The solution in Java code

public class Solution {
  public static String findNeedle(Object[] haystack) {
    for (int i=0; i<haystack.length; i++) {
      if (haystack[i] == "needle")
        return "found the needle at position "+i;
    }
    return null;
  }
}

A more succinct solution, without using a for loop:

import java.util.*;

public class Solution {
  public static String findNeedle(Object[] haystack) {
    return "found the needle at position " + Arrays.asList(haystack).indexOf("needle");
  }
}

Test cases to validate our solution

import org.junit.Test;
import static org.junit.Assert.assertEquals;

public class NeedleExampleTests {
  @Test
  public void tests() {
    Object[] haystack1 = {"3", "123124234", null, "needle", "world", "hay", 2, "3", true, false};
    Object[] haystack2 = {"283497238987234", "a dog", "a cat", "some random junk", "a piece of hay", "needle", "something somebody lost a while ago"};
    Object[] haystack3 = {1,2,3,4,5,6,7,8,8,7,5,4,3,4,5,6,67,5,5,3,3,4,2,34,234,23,4,234,324,324,"needle",1,2,3,4,5,5,6,5,4,32,3,45,54};
    assertEquals("found the needle at position 3", Solution.findNeedle(haystack1));
    assertEquals("found the needle at position 5", Solution.findNeedle(haystack2));
    assertEquals("found the needle at position 30", Solution.findNeedle(haystack3));
  }
}
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