这是在java中，我的问题是，当用户输入“depositAmount”时，如果他们使用小数点或逗号，程序就会崩溃，我知道他们的输入需要是 double 类型，但我不知道怎么说“如果用户的输入是 double 类型，接受它，否则，要求新输入”
import java.util.Scanner;
import java.util.ArrayList;
public class Engine
{
private static ArrayList<BankAccount> accounts = new ArrayList<BankAccount>();
public static void Engine()
{
Scanner Reader = new Scanner(System.in);
BankAccount n = new BankAccount();
boolean keepGoing = true;
while(keepGoing)
{
System.out.println("Welcome to The Bank of Money, what would you like to do?\n enter n to create a new account, enter e to use an existing account, or enter q to quit to main menu");
String response = Reader.nextLine();
if(response.equals("q")) keepGoing = false;
else if(response.equals("n"))
{
accounts.add(new BankAccount());
System.out.println("Your account number is: " + accounts.get(accounts.size()-1).getAccountNum());
}
else if(response.equals("e"))
{
System.out.println("what is your account number?");
Scanner Reader1 = new Scanner (System.in);
int accountNum = Reader1.nextInt();
BankAccount selectedAccount = null;
for(int i = 0; i<accounts.size();i++)
{
if (accounts.get(i).getAccountNum()==accountNum)
{
selectedAccount = accounts.get(i);
}
}
if(selectedAccount ==null)System.out.println("There is no such account. Please try again.");
else transact(selectedAccount);
}
}
}
public static void transact(BankAccount selectedAccount)
{
Scanner in = new Scanner(System.in);
int response = 0;
while(response!=7)
{
BankAccount.printTransactionMenu();
response = in.nextInt();
if(response==1)
{
System.out.println("Enter the amount that you would like to deposit");
System.out.print("$");
Scanner depositScanner = new Scanner(System.in);
double depositAmount = depositScanner.nextInt();
}
if(response==2)
{
System.out.println("Enter the amount that you would like to withdraw");
System.out.print("$");
Scanner withdrawScanner = new Scanner(System.in);
double withdrawAmount = withdrawScanner.nextInt();
if(withdrawAmount>selectedAccount.getBalance())
System.out.println("Insufficient funds");
else selectedAccount.withdraw(withdrawAmount);
}
if(response==3)
{
selectedAccount.assessInterest();
System.out.println("Your new balance is $" + selectedAccount.getBalance());
}
if(response==4)
{
System.out.println("Your account balance is $" + selectedAccount.getBalance());
}
if(response==5)
{
System.out.println("Which account would you like to transact with?");
Scanner Reader1 = new Scanner (System.in);
int transactAccountNum = Reader1.nextInt();
BankAccount transactAccount = null;
for(int i = 0; i<accounts.size();i++)
{
if (accounts.get(i).getAccountNum()==transactAccountNum)
{
transactAccount = accounts.get(i);
}
}
if(transactAccount ==null)System.out.println("There is no such account. Please try again.");
else
{
System.out.println("What amount would you like to transfer?");
Scanner transferScanner = new Scanner(System.in);
double transactAmount = transferScanner.nextDouble();
selectedAccount.transfer(transactAccount, transactAmount);
}
}
if(response==6)
{
selectedAccount.printStatement();
}
}
}
}
最佳答案
您可以使用 next() 方法从 Scanner 获取最初没有 int 或 double 值的输入。如果您知道数据类型，则可以检查它是否具有下一个 double 值 (hasNextDouble) 或您需要的任何数据类型。如果没有，您可以接受 String 类型并对其进行转换。
Scanner in = new Scanner(System.in);
String s = in.next();
从那里您可以将其解析为适当的数据类型(例如 double )。
double d = Double.parseDouble(s);
我希望这有帮助!
关于java - 当用户输入小数点时，如何错误处理代码以防止程序崩溃？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/26225965/