计算长方形的周长和面积

[java]代码库

public class demo1 
{
	private float length;
	private float width;
	
	public demo1(float l,float w)
	{
		length=l;
		width=w;
	}
	
	public void SetLength(float l)
	{
		if(length>0)
			length=l;
		else
			System.out.print("ERROR");
	}
	public float GetLength()
	{
		return length;
	}
	public float GetWidth()
	{
		return width;
	}
	float area ()
	{
		return length*width;
	}
		float zhouchang ()
		{
			return 2*(length+width);
		}
}
	package zuoye2;
public class demo2
{
	public static void main(String[] args) {
		demo1 rect = new demo1(10f, 20f);
		System.out.println("长方形的长：" + rect.GetLength());
		System.out.println("长方形的宽：" + rect.GetWidth());
		System.out.println("长方形的面积：" + rect.area());
		System.out.println("长方形的周长：" + rect.zhouchang());
	}
}