//RealDemo.java
class RealDemo
{
	public static float fPAI = 3.14f;
	public float fRadius;
	public double dTotalLength;
	public RealDemo( float fRadius )
	{	
		this.fRadius = fRadius;
	}
	public double computeLength()
	{
		dTotalLength = 2*fPAI*fRadius;
	    return dTotalLength;
	}
	public static void main(String[] args)
	{
		RealDemo aRealDemo = new RealDemo( 5 );
	   	double dLength = aRealDemo.computeLength();
	   	System.out.println("計算獲得的圓的周長為："+dLength);
	}
}