将Scanner对象连接到System.in对象并使用Scanner方法

Question

Here is my problem:

I am trying to use Scanner and System.in to take the input from a keyboard and assign it to an int variable.

This is what I have (the full program is included below):

// this program will use scanner objects and system inputs
public class Scanner
{
    public static void main(String[] args)
    {
        int number;  
             // declares integer "number"

        Scanner keyboard = new Scanner(System.in); 
  //-------------------------------------------------------------------
  // declares referance variable (Scanner class) "keyboard", creates       
  // Scanner object that 
  // reads input from System.in, then assigns address of Scanner object 
  // to the reference variable "keyboard"
  //-------------------------------------------------------------------     
        System.out.println("Enter an integer value: ");
             // displays text 
        number = keyboard.nextInt();
            // assigns keyboard input to "number" as integer value

        System.out.println("You entered the integer " + number);
           // displays "number" to see if the program worked
    }
}

When I try to compile the program in the windows command prompt using javac, I get this error message:

error: constructor Scanner in class Scanner
cannot be applied to given types;

Scanner keyboard = new Scanner(System.in);

required: no arguments
found: InputStream
reason: actual and formal argument lists differ in length

error: cannot find symbol
            number = keyboard.nextInt();
                             ^
symbol:   method nextInt()
location: variable keyboard of type Scanner
2 errors

What am I doing wrong?

Answer 1

There is a naming clash . You have to make your Scanner class unique from Java language perspective, there are 2 options to do that:

1. Rename the class
   • to some other name so that there till be no more naming clash

2. Make the Scanner class unambiguous

   • by using Fully Qualifed Names

      public static void main(String[] args) { int number; java.util.Scanner keyboard = new java.util.Scanner(System.in); System.out.println("Enter an integer value: "); number = keyboard.nextInt(); System.out.println("You entered the integer " + number); } 

Answer 2

您应该重命名类Scanner-错误是，您使用Java标准库中名称为Scanner的类。

Answer 3

import java.util.Scanner;  

public class Main {
    public static void main(String[] args){
        int number;
        Scanner keyboard = new Scanner(System.in);

        System.out.println("Enter an integer value: ");

        number = keyboard.nextInt();
        System.out.println("You entered the integer " + number);

    }
}