Java APIs

Hello again all! I'm still new to this, and having a problem using strings. The code is designed to extract price from a string. Here's what I have so far:

// calculate total price
private void calculateJButtonActionPerformed( ActionEvent event )
{
double total = 0.00;
String price;

for ( int counter = 0; counter < userArrayList.size();
counter++ )
{
// convert current item to string
price = ( String ) userArrayList.get( counter );
double priceBegin = userArrayList.indexOf( "$" );

// store substring
String priceText = listItem.substring(
priceBegin );
double priceEnd = Double.parseDouble( priceText );

total += priceEnd;

}

The problem I'm having is storing the substring. The error I get now is:

C:\SimplyJava\SupplyCalculator\SupplyCalculator.java:255: cannot resolve symbol
symbol : variable listItem
location: class SupplyCalculator
String priceText = listItem.substring(

Does anyone know what I might be doing wrong?

Thanks for any help you can give!