異常在線程「主要」 java.lang.Error的：未解決的編譯問題：

Question

這是我得到

Exception in thread "main" java.lang.Error: Unresolved compilation problems: 
    Scanner cannot be resolved to a type 
    Scanner cannot be resolved to a type 

    at hello.main(hello.java:11) 

這是我的代碼錯誤。像import java.util.Scanner;

Answer 1

你有進口Scanner類你需要：

import java.util.Scanner; 

在你的文件的頂部。你必須導入它。

Answer 2

public class hello { 

    public static void main(String[] args) { 
     // TODO Auto-generated method stub 

     double area; 
     double radius; 

     Scanner input = new Scanner(System.in); 
     System.out.print("반지름을 입력하시오: "); 
     radius = input.nextDouble(); 
     area = 3.14 * radius * radius; 

     System.out.println(area); 
    }  
}