Eclipse说：系统无法解析为变量

Question

我是Java和Eclipse的新手，并且一直在观看一些教程，我遵循了1个教程但是我得到了错误“系统无法解析为变量”，然后我决定再次按照它完全相同而且它说了同样的错误...

package java.testing;

import java.util.Scanner;
public class TestingJava
{
    public static void main(String[] args)
    {
        Scanner in=new Scanner(System, in);
        int age;
        System.out.println("How old are you?");
        age=in.next();
        if (age >= 21)
            System.out.println("You are old enough to drink");
        else
            System.out.println("You are not old enough to drink");
    }
}