很基本的一个程序，勿喷！
/**
*请比较以下两个程序的区别，说出为什么会有差异？
*
*/
import java.util.Scanner;
class Test1
{
public static void main(String[] args)
{
  Scanner input = new Scanner(System.in);
  final double PI = 3.14159;
  
  System.out.print("Enter the radius and length of a cylinder: ");
  double radius = input.nextDouble();
  double length = input.nextDouble();
  
  double area = radius * radius * PI;
  System.out.println("The area is "+area);
  System.out.println("The volume is "+area*length);
}
}
/*
import java.util.Scanner;
class Test1
{
public static void main(String[] args)
{
  Scanner input = new Scanner(System.in);
  final double PI = 3.14159;
  
  System.out.print("Enter the radius and length of a cylinder: ");
  double radius = input.nextDouble();
  double length = input.nextDouble();
  
  double area = radius * radius * PI;
  double volume = area * length;
  System.out.println("The area is "+area);
  System.out.println("The volume is "+volume);
}
}
*/

很基本的一个程序，勿喷！
/**
*请比较以下两个程序的区别，说出为什么会有差异？
*
*/
import java.util.Scanner;
class Test1
{
public static void main(String[] args)
{
  Scanner input = new Scanner(System.in);
  final double PI = 3.14159;
  
  System.out.print("Enter the radius and length of a cylinder: ");
  double radius = input.nextDouble();
  double length = input.nextDouble();
  
  double area = radius * radius * PI;
  System.out.println("The area is "+area);
  System.out.println("The volume is "+area*length);
}
}
/*
import java.util.Scanner;
class Test1
{
public static void main(String[] args)
{
  Scanner input = new Scanner(System.in);
  final double PI = 3.14159;
  
  System.out.print("Enter the radius and length of a cylinder: ");
  double radius = input.nextDouble();
  double length = input.nextDouble();
  
  double area = radius * radius * PI;
  double volume = area * length;
  System.out.println("The area is "+area);
  System.out.println("The volume is "+volume);
}
}
*/