Question

我正在制作今天午夜到期的课程，我无法理解为什么它会给我这个Null Point Exception错误。如果你们能看看我的代码并帮助我，我将非常感激。

该项目的目标如下。

程序声明：编写一个使用以下数组作为字段的Payroll类：
- employeeId - 包含员工ID号的7个整数数组。应使用以下数字初始化数组字段：
  1. 5658845
  2. 4520125
  3. 7895122
  4. 8777541
  5. 8451277
  6. 1302850
  7. 7580489
- 小时 - 一组七个整数，用于保存每位员工的工作小时数
- payRate - 七个双打的数组，用于保存每位员工的小时费率。
- 工资 - 用于支付每位员工工资总额的七个双打数字。
该类应通过下标关联每个数组中的数据。例如，hours数组的元素0中的数字应该是员工的工作小时数，该员工的ID号存储在employeeId数组的元素0中。同样的员工工资率应该存储在payRate数组的元素0中。除了适当的访问器和mutator方法之外，该类还应该有一个方法，该方法接受员工的id号作为参数，并返回该员工的总工资。在一个完整的程序中展示课程，该程序显示每个员工编号并要求用户输入员工的工时和工资率。然后它应显示每个员工的身份证号码和工资总额。
- 输入验证：不接受数字和负值小于6.00的负值。

int[] employeeId;
int[] hours;
double[] payRate;
double[] wages;

Scanner kboard = new Scanner(System.in);

public ParrishPayroll(int[] ids){

    employeeId = new int[ids.length];
    // Copy the values in ids
    for (int index = 0; index < ids.length; index++)
        employeeId[index] = ids[index];

    System.out.println("Employee ID's");
    System.out.println(Arrays.toString(employeeId));

    System.out.println("Please enter the id number you would like to edit.");
        int input = kboard.nextInt();

        if(input == 5658845){
            int index = 0;
            setHours(index);
            }
        else if(input == 4520125){
            int index = 1;
            setHours(index);
            }
        else if(input == 7895122){
            int index = 2;
            setHours(index);
            }
        else if(input == 8777541){
            int index = 3;
            setHours(index);
            }
        else if(input == 8451277){
            int index = 4;
            setHours(index);
            }
        else if(input == 1302850){
            int index = 5;
            setHours(index);
            }
        else if(input == 7580489){
            int index = 6;
            setHours(index);
            }
        else {
            System.out.println("Invalid ID number!");

            }
}//end startSequence

public void setHours(int i){

    System.out.println("How many hours were worked?");
    hours[i] = kboard.nextInt();    
        if(hours[i] < 0){
            System.out.println("Please input a positive number.");
            kboard.nextInt(hours[i]);
            setPayRate(i);
        }
        else
            setPayRate(i);

}

public void setPayRate(int index){

    int input = index;

    System.out.println("What is the employee's pay rate?");
    payRate[input] = kboard.nextDouble();
        if(payRate[input] < 0){
            System.out.println("Please input a positive number.");
            payRate[input] = kboard.nextDouble();
            calcWages(input);
        }
        else if(payRate[index] < 6.00){
            System.out.println("Wages must be higher than $6.00.");
            payRate[input] = kboard.nextDouble();
            calcWages(input);
        }
}

public void calcWages(int index){

    int input = index;

    wages[input] = hours[input] * payRate[input];

}


public void getGross(int i){

    int input = i;

    if(input == 5658845){
        System.out.print("Employee number: " + input + " wages: " + wages[0]);
        }
    else if(input == 4520125){
        System.out.print("Employee number: " + input + " wages: " + wages[1]);
        }
    else if(input == 7895122){
        System.out.print("Employee number: " + input + " wages: " + wages[2]);
        }
    else if(input == 8777541){
        System.out.print("Employee number: " + input + " wages: " + wages[3]);
        }
    else if(input == 8451277){
        System.out.print("Employee number: " + input + " wages: " + wages[4]);
        }
    else if(input == 1302850){
        System.out.print("Employee number: " + input + " wages: " + wages[5]);
        }
    else if(input == 7580489){
        System.out.print("Employee number: " + input + " wages: " + wages[6]);
        }
    else {
        System.out.println("Invalid ID number!");
        getGross(input);
        }


   }


public static void main(String[] args){

    int[] idlist = {5658845, 4520125, 7895122, 8777541, 8451277, 1302850, 7580489};

    ParrishPayroll user1 = new ParrishPayroll(idlist);

    Scanner kboard = new Scanner(System.in);
    System.out.println("What employee would you like to see the gross wages for?");
    int i = kboard.nextInt();
    user1.getGross(i);    

}

Answer 1

您似乎没有初始化hours，payRate或wages变量，这意味着它们都是空的。当您调用hours[i] = kboard.nextInt()时，它将抛出NullPointerException，因为您无法设置null的 i 元素。

在尝试使用hours = new int[whatever]变量之前，请确保您有hours之类的行（其他两个变量相同）。你已经适合employeeId，所以请遵循这种模式。

代码错误，NullPointException

1 个答案: