java - 我做错了什么会得到这个额外的输出吗？

Question

这个问题已经有答案了:

Trouble using nextInt and nextLine() (1 个回答)

已关闭 8 年前。

System.out.println("Enter UPC for an item you want, enter -1 when done");

do {
    System.out.print("\nEnter a UPC ");
    targetUPC = keyboard.nextLine();
    RetailItem temporary = new RetailItem("Default", 0, 0, targetUPC);

    if(itemList.indexOf(temporary) > -1) {
        RetailItem itemIndex = itemList.get(itemList.indexOf(temporary));
        System.out.println("\n" + itemIndex);
        System.out.print("How many would you like? ");
        numOfItems = keyboard.nextInt();
        itemIndex.setInStock(itemIndex.getInStock() - numOfItems);
        totalCost = numOfItems * itemIndex.getPrice();
    }

    if(itemList.indexOf(temporary) == -1 && !targetUPC.equals("0")) {
        System.out.print(targetUPC + " not found.\n");
    }

这是它的一些输出:

Enter UPC for an item you want, enter -1 when done

Enter a UPC: 999

999 not found.

Enter a UPC: 61835

Description: Corn Crisps
Price: $9.45
Number in stock: 35
UPC: 61835

How many would you like? 5

Enter a UPC  not found.                  //Why am I getting this?

Enter a UPC 0

Total cost: $47.25

我脑子里想了很久，还是想不出来

Answer 1

您正在将 nextInt() 与 nextLine() 混合在一个循环中，该 nextInt() 会留下尾随换行符。读取尾随换行符，例如，

numOfItems = keyboard.nextInt();
keyboard.nextLine();

或者首先消耗整行，例如，

numOfItems = Integer.parseInt(keyboard.nextLine().trim());