提问人：Mitchell 提问时间：6/20/2023 更新时间：6/21/2023 访问量：40
陷入一个持续的循环
Stuck in a constant loop
问：
我的 StoreFront 类在选择选项 3 返回产品时调用此方法。这种方法应该问我输入产品，把我的控制台再次提示我说。不确定从这里去哪里？为什么我被困在一个持续的循环中？这也是我的方法"Enter the name of the product you want to return: ""Enter the name of the product you want to return: "
public SalableProduct returnProduct(String name) {
Scanner scnr = new Scanner(System.in);
System.out.println("Enter the name of the product you want to return: ");
String returnProd = scnr.nextLine();
SalableProduct productReturned = returnProduct(returnProd);
if (productReturned == null) {
System.out.println("Item not in cart");
} else {
removeItem(productReturned);
addItem(productReturned);
System.out.println(productReturned.getName() + " successfully returned");
}scnr.close();
return null;
}
答：
0赞
Mitchell
6/21/2023
#1
我重构了我的代码并添加了一个 for 循环，这样它就会检查我购物车中的产品，然后在迭代后中断。
public void returnProduct(String name) {
Scanner scnr = new Scanner(System.in);
System.out.println("Enter the name of the product you want to return: ");
String returnProd = scnr.nextLine();
SalableProduct productReturned = null;
for (SalableProduct product : salableProduct) {
if (product.getName().equalsIgnoreCase(returnProd)) {
productReturned = product;
break;
}
}
if (productReturned == null) {
System.out.println("Item not in cart");
} else {
removeItem(productReturned);
InventoryManager inventoryManager = new InventoryManager();
inventoryManager.addProduct(productReturned);
System.out.println(productReturned.getName() + " successfully returned");
}
scnr.close();
}
另一个错误出现在程序将退出的地方，因为 scnr.close（） 与 System.in 相关联，所以我使用自定义 FilterInputStream 并包装 System.in。
更新代码：
public void returnProduct(String name) {
FilterInputStream filterInputStream = new FilterInputStream(System.in) {
@Override
public void close() throws IOException {
}
};
// FilterInputStream so when scanner is closed it does not quit the program and
// handles errors.
Scanner scnr = new Scanner(filterInputStream);
System.out.println("Enter the name of the product you want to return: ");
String returnProd = scnr.nextLine();
SalableProduct productReturned = null;
for (SalableProduct product : salableProduct) {
if (product.getName().equalsIgnoreCase(returnProd)) {
productReturned = product;
break;
}
}
if (productReturned == null) {
System.out.println("Item not in cart");
} else {
removeItem(productReturned);
InventoryManager inventoryManager = new InventoryManager();
inventoryManager.addProduct(productReturned);
System.out.println(productReturned.getName() + " successfully returned");
}
scnr.close();
}
评论
0赞
David Conrad
6/21/2023
您不应关闭扫描仪，因为它正在您未打开的 System.in 上运行。
0赞
Mitchell
6/21/2023
是的，在我解决了循环问题之后，我实际上只是注意到了这一点。但是我刚刚完成了添加 FilterInputStream 并包装 System.in 以便它覆盖以防止在 scnr 关闭时关闭 System.in。我将添加代码以供参考。
评论