Please help me, IndexOf problem

Hi, I am having big problems using IndexOf. I am trying to create a table of numbers from 1-100 and every time a 5 appears change the word to fiz.

I can do this using multiples of 5 but not when a 5 appears, for example 51 needs to be changed to "fiz"

any help would be greatfully appreciated.



class cw1d
{
public static void main (String[] args)
{
System.out.println("|-----------------------------------------------");
System.out.println("| FizBuz Simulator");
System.out.println("| by ");
System.out.println("|-----------------------------------------------");

int counter;
String number="0";


for (counter=1; counter<=100; counter++)

{
if (counter%5==0 && counter%7==0)

{
System.out.print("fizbuz\t");
}

number=number.indexOf(counter);

// if (counter%5==0)
// {
// System.out.println("fiz");
// }
// else


if (number.indexOf=="5" || counter%5==0)

{
System.out.print("fiz\t");
}


else

{
System.out.println(counter);
}


if (counter%7==0)

{
System.out.print("buz\t");
}


else


{
System.out.print(counter);
System.out.print("\t");

}



}
}


}

turn the number into a string then search for "5" in that string.