Counting unique characters in a String given by the user

Question

I have to write a program that counts the uniques characters in a String given by the user. For example \"abc\" returns 3 and \"aabbccd\" returns 4. I am not allow to use advan

Answer 1

If your stuck on Java 7, you can use an ArrayList and just add unique values to it, then return the size of the ArrayList, which should always work even if the count is zero.

 import java.util.ArrayList;

 public int getUniqeCount( String arg )
 {
     ArrayList unique = new ArrayList();
     for( int i = 0; i < arg.length(); i++)
         if( !unique.contains( arg.charAt( i ) ) )
             unique.add( arg.charAt( i ) );
     return unique.size();
 }