类名大写

     第一、类名要大写(Test)；

     第二、可以有多个类，但是只能一个是public。

import java.util.*;
public class Test
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
double oblength,obheight;
Oblong myoblong;
System.out.print("please enter the length");
oblength = sc.nextDouble();
System.out.print("please enter the height");
obheight = sc.nextDouble();
myoblong = new Oblong(oblength,obheight);
System.out.println("length="+myoblong.getLength());
System.out.println("height="+myoblong.getHeight());
System.out.println("area="+myoblong.calculateArea());
System.out.println("perimeter="+myoblong.calculatePerimeter());
}
}

class Oblong
{
private double length;
private double height;
public Oblong(double a,double b)
{
length = a;
height = b;
}
public double getLength()
{
return length;
}
public double getHeight()
{
return height;
}
public double calculateArea()
{
return length * height;
}
public double calculatePerimeter()
{
return 2*(length + height);
}
}