java - "error: variable keyboard is already defined in method main(String [])"

Question

当我尝试运行我的程序时，我收到了几条错误消息，其中最让我困扰的是“错误:变量键盘已在方法 main(String []) 中定义”

我是否应该在我的程序中多次使用 main(String []) ，或者只是在开始时使用它？这里还有什么问题吗？

这是我的程序的开头:

public static void main(String[]args)
{
    String firstName, lastName;
    int moviesDownloaded, stateResidency;
    double movieCost, netPayment, tax, discount, totalCharge, payment, taxRate;

    System.out.println("Enter your first name:");
    Scanner keyboard = new Scanner(System.in);
    firstName = keyboard.nextString();

    System.out.println("Enter your last name:");
    Scanner keyboard = new Scanner(System.in);
    lastName = keyboard.nextString();

    System.out.println("Enter the number of movies downloaded:");
    Scanner keyboard = new Scanner(System.in);
    moviesDownloaded = keyboard.nextInt();

    System.out.println("Enter the cost per movie:");
    Scanner keyboard = new Scanner(System.in);
    movieCost = keyboard.nextDouble();

    System.out.println("Indicate your state of residency. Enter 1 for Mississippi or 2 for any other state.");
    Scanner keyboard = new Scanner(System.in);
    stateResidency = keyboard.nextInt();

Answer 1

您应该只声​​明并初始化键盘一次，然后使用它。因此，除了第一行之外，删除所有类型为:Scanner Keyboard = new Scanner(System.in); 的行。否则，您尝试多次声明同一个变量，因此 java 会提示。