java - 导入扫描仪类的问题

Question

我正在尝试执行以下代码，但不断收到此错误：

错误：在 ScannerDemo 类中找不到 Main 方法，请将 main 方法定义为： public static void main(String[] args)

import java.util.Scanner;
class ScannerDemo
public class Main {

    public static void main (String [] args)
    {
        Scanner sc = new Scanner(System.in);
        String userName;

        System.out.println("Enter a number");
        username = sc.nextLine();
        System.out.println("your number is" + username + "enter your next number");
        username2 = sc.nextline();
        System.out.println("your total is" + username2 );     
    }
}

我想我一定是错误地导入了 Scanner 类，我尝试了不同的方法，但还没有对我有用。

Answer 1

您在顶部连续有两个类声明！这是错误的。你的导入没问题。尝试：

import java.util.Scanner;
public class ScannerDemo {
  public static void main(String[] args) {
    ...
  }
}

Answer 2

你的类定义是错误的。您正在尝试定义两个类，ScannerDemo并且Main. 代替：

class ScannerDemo
 public class Main

只需：

public class ScannerDemo

此外，在您的main方法中，您应该引用userName变量，而不是username，并且您没有定义username2. 请注意，Java 标识符区分大小写：

public static void main (String [] args)
{
  Scanner sc = new Scanner(System.in);
  System.out.println("Enter a number");
  String userName = sc.nextLine();
  System.out.println("your number is" + username + "enter your next number");
  String username2 = sc.nextline();
  System.out.println("your total is" + username2 );
}

Answer 3

import java.util.Scanner;

public class ScannerDemo {

    public static void main (String [] args)
    {
        Scanner sc = new Scanner(System.in);
        String userName;

        System.out.println("Enter a number");
        username = sc.nextLine();
        System.out.println("your number is" + username + "enter your next number");
        username2 = sc.nextline();
        System.out.println("your total is" + username2 );     
    }
}

Answer 4

 import java.util.Scanner;

 public class ScannerDemo {

      public static void main (String [] args) {

         Scanner sc = new Scanner(System.in);
         String userName;

         System.out.println("Enter a number");
         int userName = sc.nextInt();
         System.out.println("your number is " + userName);
         System.out.println("enter your next number");
         int userName2 = sc.nextInt();
         System.out.println("your total is " + (userName2 + userName));     
     }
 }

希望这可以帮助

Answer 5

import java.util.Scanner;


public class ScannerDemo {

public static void main (String [] args) {

        Scanner sc = new Scanner(System.in);
        String userName;

        System.out.println("Enter a number");
        int username = sc.nextInt();
        System.out.println("your number is " + username);
        System.out.println("enter your next number");
        int username2 = sc.nextInt();
        System.out.println("your total is " + (username2 + username));     
    }
}