//Display the table of invoices using Invoice toString().
        //Print table header.
        System.out.println("Part number\tPart description\tQuantity\tPrice per item\tValue");
        invoices.stream()
                .forEach(System.out::print);
        
        //a)Use streams to sort Invoice object by partDecsription, then display the results.
        System.out.println("\nInvoices sorted by Part description\nPart number\tPart description\tQuantity\tPrice per item\tValue");
        invoices.stream().sorted(Comparator.comparing(Invoice::getPartDescription)).forEach(System.out::print);  
        
        //b)Use streams to sort Invoice object by price, then display the results.
        System.out.println("\nInvoices sorted by Price\nPart number\tPart description\tQuantity\tPrice per item\tValue");
        invoices.stream().sorted(Comparator.comparing(Invoice::getPricePerItem)).forEach(System.out::print);
        
        //c)Use streams to map each Invoice to its partDescription and quantity, 
        //  then display the results.
        System.out.println("\nPart Description and Quantity for each Invoice\nPart description\tQuantity");
        invoices.stream().sorted(Comparator.comparing(Invoice::getQuantity))
        .map(invoice -> String.format("%-20s %d\n", invoice.getPartDescription(), invoice.getQuantity()))
        .forEach(System.out::print);

//Display the table of invoices using Invoice toString().
        //Print table header.
        System.out.println("Part number\tPart description\tQuantity\tPrice per item\tValue");
        invoices.stream()
                .forEach(System.out::print);
        
        //a)Use streams to sort Invoice object by partDecsription, then display the results.
        System.out.println("\nInvoices sorted by Part description\nPart number\tPart description\tQuantity\tPrice per item\tValue");
        invoices.stream().sorted(Comparator.comparing(Invoice::getPartDescription)).forEach(System.out::print);  
        
        //b)Use streams to sort Invoice object by price, then display the results.
        System.out.println("\nInvoices sorted by Price\nPart number\tPart description\tQuantity\tPrice per item\tValue");
        invoices.stream().sorted(Comparator.comparing(Invoice::getPricePerItem)).forEach(System.out::print);
        
        //c)Use streams to map each Invoice to its partDescription and quantity, 
        //  then display the results.
        System.out.println("\nPart Description and Quantity for each Invoice\nPart description\tQuantity");
        invoices.stream().sorted(Comparator.comparing(Invoice::getQuantity))
        .map(invoice -> String.format("%-20s %d\n", invoice.getPartDescription(), invoice.getQuantity()))
        .forEach(System.out::print);