how to compare elements in a string array in java?

Question

I am trying to find duplicate words in a string array.

Here is my code for the comparison:

   for ( int j = 0 ; j < wordCount ; j++)
   {    
             


        

Answer 1

NullPointerException means that one of your array members is not set (i.e. it is null)

Don't use == to compare strings.

You are on the right track - chances are stringArray[] contains some members that are not set. Eacy fix is to null check before using the values.

for ( int j = 0 ; j < wordCount ; j++)
   {    
       for (int i = wordCount-1 ; i > j ; i--)
       {       
           String wordi = stringArray[i];
           String wordj = strinArray[j];
           // If both are null it won't count as a duplicate.
           // (No real need to check wordj - I do it out of habit)
           if (wordi != null && wordj != null && wordi.compareTo(wordj) == 0 && i!=j)
           {
               //duplicate
               duplicates++;
           }
       }
   }
   wordCount -= duplicates;
   System.out.print("\nNumber of words, not including duplicates: " + wordCount);