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);
  }
}