谁来帮帮我~~多谢了

[klaire]

谁能帮我详细分析一下这个程序呢?谢谢了!!!!

package test.oo.shape;


public class Rectangle extends MyShape
{

private double length;
private double width;
public static final String SIDEERR = "长方形的长和宽必须大于0！";

public Rectangle()
{
init();
}

public Rectangle(double a, double b)
{
if ((a <= 0) || (b <= 0))
{
System.err.println(SIDEERR);
init();
}
else
{
this.length = a;
this.width = b;
}
}

private void init()
{
this.length = 5;
this.width = 4;
}

public double getGirth()
{
return (this.length + this.width) * 2;
}
public double getArea()
{
return this.length * this.width;
}
public String toString()
{
return "矩形的名字是：" + this.name + "，长为" + this.length + "，宽为" + this.width;
}
public double getLength()
{
return length;
}
public void setLength(double length)
{
if (length > 0)
{
this.length = length;
}
else
{
System.err.println(SIDEERR);
}
}
public double getWidth()
{
return width;
}
public void setWidth(double width)
{
if (width > 0)
{
this.width = width;
}
else
{
System.err.println(SIDEERR);
}
}
public static void main(String[] args)
{
Rectangle test = new Rectangle();
test.setName("myRectangle");
System.out.println( test.toString());
System.out.println("矩形的周长是：" + test.getGirth());
System.out.println("矩形的面积是：" + test.getArea());
}
}