shoppingcartapplication.java

ssd3 exercise1。正确的

import  java.io.*;
import  java.util.*;

public class ShoppingCartApplication  {

	private static BufferedReader  stdIn =
		new  BufferedReader(new  InputStreamReader(System.in));
	private static PrintWriter  stdOut =
		new  PrintWriter(System.out, true);
	private static PrintWriter  stdErr =
		new  PrintWriter(System.err, true);

	private ShoppingCart cart;

	public static void main(String[]  args) throws IOException  {

		ShoppingCartApplication application = new  ShoppingCartApplication();

		application.run();
	}

	private void run() throws IOException  {

		cart = new  ShoppingCart();

		int  choice = getChoice();

		while (choice != 0)  {

			if (choice == 1)  {
				stdOut.print("Product [name_qtr_price]>");
				stdOut.flush();
				cart.addProduct(readProduct());
			} else if (choice == 2)  {
				stdOut.println(cart.toString());
			} else if (choice == 3)  {
				stdOut.println(cart.getTotalValue());
			}

			choice = getChoice();
		}
	}

	private int  getChoice() throws IOException  {

		do  {

			int input;

			try  {
				stdErr.println();
				stdErr.print("[0]  Quit\n"
							 + "[1]  Add Product\n"
							 + "[2]  Display Products\n"
							 + "[3]  Display Total\n"
							 + "choice>");
				stdErr.flush();

				input = Integer.parseInt(stdIn.readLine());

				if (0 <= input && 3 >= input)  {

					return  input;

				} else {
					stdErr.println("Invalid choice:  " + input);
				}
			} catch (NumberFormatException  nfe)  {
				stdErr.println(nfe);
			}
		}  while (true);
	}
  
	private Product readProduct() throws IOException {

		final String DELIM = "_";

		String name = "";
		int quantity = 0;
		double price = 0.0;
		
		do{
			
			try{
				
				StringTokenizer  tokenizer =
					new  StringTokenizer(stdIn.readLine(),DELIM);
					if (tokenizer.countTokens() != 3) {
						 throw new NumberFormatException("Invalid input\nProduct [name_qtr_price]>"); 
						
					} else {
						name = tokenizer.nextToken(); 
						quantity = Integer.parseInt(tokenizer.nextToken()); 
						price = Double.parseDouble(tokenizer.nextToken()); 
						if(quantity<0||price<0){
						
							throw new NumberFormatException("Invalid input\nProduct [name_qtr_price]>");}
						
					   else{
					   
							return new Product(name,quantity,price);
						
					   }	
					}
						
			
		} catch (NumberFormatException  nfe)  {
			stdErr.println( nfe.getMessage());
			
			}
			
		} while (true);
	}
	
}