急请大神帮小弟我看一下，这里异常要如何改，千恩万谢！多谢~_Java相关

急急急~~~~~请大神帮我看一下，这里错误要怎么改，千恩万谢！谢谢~~~~~
public abstract class Area {
public void double area(){

}
public class RoundArea extends Area{
double roundarea , width;
double area(double width){
roundarea=Math.PI*width*width;
return roundarea;
}
}
public class RectArea extends Area{
double rectarea ,length, width;
double area(double length,double width){
rectarea=length*width;
return rectarea;
}
}
public class ImpleArea{
double length,width;
double getx(){
System.out.println("length="+length);
System.out.println("length="+width);
return length;
return width;
}
}

public static void main(String[] args) {
// TODO Auto-generated method stub

RoundArea c=new RoundArea ();
c.area();
System.out.println("圆的面积是"+c);
RectArea a=new RectArea();
a.area();
System.out.println("长方形的面积是"+a);

}

}

------解决方案--------------------------------------------------------
public void double area()我看不懂这句，返回值到底是void还是double呢
------解决方案--------------------------------------------------------
想理解java里类的多态？
你定义了一个抽象类叫做面积~~里面有个一个求面积的方法~~
接下里你开始定义了圆类还有矩形类 ~~这里圆应该有一个半径的变量就是width
但是没看到你给这个属性赋值
也没看到什么构造方法~
那你这个面积怎么可能求的出来啊？好比你定义了一个圆去不告诉他这个圆的半径是多少让它求面积~~这咋求的出来啊！！！
矩形也是类似的~~~

public class ImpleArea{
double length,width;
double getx(){
System.out.println("length="+length);
System.out.println("length="+width);
return length;
return width;
}
}
还有你这个类我就真不懂你想干啥？
------解决方案--------------------------------------------------------

Java code

    public class RoundArea extends Area{    double roundarea , width;    double area(double width){    roundarea=Math.PI*width*width;    return roundarea;       }}.......RoundArea c=new RoundArea ();c.area(1.0);//根据你在RoundArea定义的方法需要你传入一个double 类型的参数System.out.println("圆的面积是"+c); //这样就出来结果了//矩形类似的
------解决方案--------------------------------------------------------
Area.java

	public abstract class Area {
		public  double area(double x){
		
			return Math.PI * x * x ;
		}
		public  double area(double x, double y ){
		
			return x * y ;
		}
	}

RoundArea.java

	public class RoundArea extends Area{
			//private double roundarea , width;
			/**
			public double area(double width){
				roundarea=Math.PI*width*width;
				return roundarea;
			}
			*/
	}

RectArea.java

	  public class RectArea extends Area{
			//private double rectarea ,length, width;
			
			/**
			public double area(double length,double width){
				rectarea=length*width;
				return rectarea;
			}
			*/
		}


ImpleArea.java
	  public class ImpleArea{
				private double length,width;
				
				//保留默认构造函数
				public ImpleArea(){
				}
				//定义一个构造函数 ，初始化私有变量
				public ImpleArea(double length, double width){
					this.length = length ;
					this.width  = width ;
				}
				
				public double getx(){
					System.out.println("length="+length);
					System.out.println("length="+width);
					
					//到底是想返回 length 还是 width 还是 length * width ,看你的方法名定义getx()应该是返回 length  
					return length;
					//return width;
				}
		}


Test.java

public class Test{
		public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		    Area c = new RoundArea() ;
		    double dc = c.area(10.1) ; // 你定义的area方法是有一个double参数的，调用的时候需要放入参数啊