public class Main
{
public static int getLongestSubstringNoRepeats( String string ){
    int iLongestSoFar = 0;
    char charPrevious = 0;
    int xCharacter = 0;
    int iCurrentLength = 0;
    while( xCharacter < string.length() ){
        char charCurrent = string.charAt( xCharacter );
        iCurrentLength++;
        if( charCurrent == charPrevious ){
            if( iCurrentLength > iLongestSoFar ) iLongestSoFar = iCurrentLength;
            iCurrentLength = 1;
        }
        charPrevious = charCurrent;
    }
    return iCurrentLength > iLongestSoFar ? iCurrentLength : iLongestSoFar;
}
 
   public static void main(String[] args)
   {
      System.out.println(getLongestSubstringNoRepeats("AABGAKGIMN"));
   }
}

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