Compare elements in String java

August 13, 2022

I’ve got String array with data.

And ArrayList for result:

String[] arr = word.split("aaccde");
List<Boolean> list = new ArrayList<>();

I need to compare each element with other elements.

If array contains element only one time – false

if array contains element several times – true

Output in List should be:

[true, true, true, true, false, false]

I try to use two loops, but it not worked corect:

      for (int i = 0; i < arr.length; i++) {
        for (int k = i + 1; k < arr.length; k++) {
            if (!arr[i].equals(arr[k])) {
                list.add(i, false);
            } else {
                list.add(i, true);
            }
        }
    }

How to achieve result in list:

[true, true, true, true, false, false]

>Solution :

For each string in the array a, scan the array a for a matching string. The matching must not be itself !(i==j). The |= simply make b[i] true if there’s one or more matches.

import java.util.*;
public class Main{
    public static void main(String[] args) {
       String  [] a = {"cat", "dog", "cat", "fish", "dog", "bear"};
       boolean [] b = new boolean[a.length];
       for(int i=0; i<a.length; i++)
         for(int j=0; j<a.length; j++)
            b[i] |= (i!=j && a[i].equals(a[j]));
       System.out.println(Arrays.toString(b));
    }
}

Output