24.5. Pet Store Example: Java Functions in the Rules Extracted from PetStore.drl

function void doCheckout(JFrame frame, WorkingMemory workingMemory) {
    Object[] options = {"Yes",
                        "No"};
                            
    int n = JOptionPane.showOptionDialog(frame,
        "Would you like to checkout?",
        "",
        JOptionPane.YES_NO_OPTION,
        JOptionPane.QUESTION_MESSAGE,
        null,
        options,
        options[0]);

    if (n == 0) {
        workingMemory.setFocus( "checkout" );
    }   
}

function boolean requireTank(JFrame frame, WorkingMemory workingMemory, Order order, Product fishTank, int total) {
    Object[] options = {"Yes",
                        "No"};
                            
    int n = JOptionPane.showOptionDialog(frame,
        "Would you like to buy a tank for your " + total + " fish?",
        "Purchase Suggestion",
        JOptionPane.YES_NO_OPTION,
        JOptionPane.QUESTION_MESSAGE,
        null,
        options,
        options[0]);
                                             
    System.out.print( "SUGGESTION: Would you like to buy a tank for your "
                      + total + " fish? - " );

    if (n == 0) {
        Purchase purchase = new Purchase( order, fishTank );
        workingMemory.insert( purchase );
        order.addItem( purchase );
        System.out.println( "Yes" );
    } else {
        System.out.println( "No" );
    }      
    return true;
}