java - 扫描仪问题

Question

我正在制作一个程序，初始化每个员工的值，然后最终显示出来。在大约第四个循环之后，我一直遇到扫描仪问题，我收到错误 java.lang.IllegalStateException 扫描仪关闭，任何建议都会有帮助。

for(int x = 0; x < 5; x++)
{
    System.out.println("For an employee who get salary enter #1.");
    System.out.println("For an employee who's hourly enter #2.");
    System.out.println("For an employee who's paid comission enter #3");
    System.out.println("For an employee who's base & comission enter #4 or 0 to quit.");
    Employees[x] = keyboard.nextInt();
    switch (Employees[x])
    {
        case 1:
            System.out.println("Please enter your first name.");
            FName[x] = keyboard.next();
            System.out.println("Please enter your last name.");
            LName[x] = keyboard.next();
            System.out.println("Please enter your social security in format 111-11-1111");
            SS[x] = keyboard.next();
            System.out.println("Please enter your salary amount $.");
            Check[x] = keyboard.nextDouble();
            SalariedEmployee salariedEmployee = 
                 new SalariedEmployee( FName[x], LName[x], SS[x], Check[x] );
            employees[x] = salariedEmployee;
            break;
        case 2: 
            System.out.println("Please enter your first name.");
            FName[x] = keyboard.nextLine();
            System.out.println("Please enter your last name.");
            LName[x] = keyboard.nextLine();
            System.out.println("Please enter your social security in format 111-11-1111");
            SS[x] = keyboard.nextLine();System.out.println("Please enter your first name.");
            System.out.println("How many hours were worked?");
            Hours[x] = keyboard.nextInt();
            System.out.println("How much paid per hour?");
            Rate[x] = keyboard.nextDouble();
            HourlyEmployee hourlyEmployee = 
            new HourlyEmployee( FName[x], LName[x], SS[x], Hours[x], Rate[x] );
            employees[x] = hourlyEmployee;
            break;
        case 3: 
            System.out.println("Please enter your first name.");
            FName[x] = keyboard.nextLine();
            System.out.println("Please enter your last name.");
            LName[x] = keyboard.nextLine();
            System.out.println("Please enter your social security in format 111-11-1111");
            SS[x] = keyboard.nextLine();System.out.println("Please enter your first name.");
            System.out.println("What was your weekly sale?");
            CommissionSales[x] = keyboard.nextDouble();
            System.out.println("What is your percentage paid commission?");
            CommissionRate[x] = keyboard.nextDouble();
           HourlyEmployee hourlyEmployee = 
            new HourlyEmployee( FName[x], LName[x], SS[x], Hours[x], Rate[x] );
            employees[x] = hourlyEmployee;
            break;
        case 4:
            System.out.println("Please enter your first name.");
            FName[x] = keyboard.nextLine();
            System.out.println("Please enter your last name.");
            LName[x] = keyboard.nextLine();
            System.out.println("Please enter your social security in format 111-11-1111");
            SS[x] = keyboard.nextLine();
            System.out.println("What was your weekly sale?");
            CommissionSales[x] = keyboard.nextDouble();
            System.out.println("What is your percentage paid commission?");
            CommissionRate[x] = keyboard.nextDouble();
            System.out.println("Please enter your salary amount $.");
            Check[x] = keyboard.nextDouble();
            BasePlusCommissionEmployee basePlusCommissionEmployee = 
            new BasePlusCommissionEmployee( FName[x], LName[x], SS[x], CommissionSales[x], CommissionRate[x], Check[x]);
            employees[x] = basePlusCommissionEmployee;
            break;
    }       

Answer 1

如果您在尝试使用扫描仪时关闭了扫描仪，那么您使用的所有Scanner方法都会抛出IllegalStateException。在代码中的某个位置，您可能有 keyboard.close()。删除这一行，或者将其移动到程序的末尾，就可以了。来自 Java 文档:

Attempting to perform search operations after a scanner has been closed will result in an IllegalStateException.