abstract class Shape
{
protected double length;
protected double width;
Shape(final double num,final double num1)
{
length=num;
width=num1;
}
abstract double area();
}
class Square extends Shape
{
Square(final double num,final double num1)
{
super(num,num1);
}
double area()
{
System.out.println("正方形的面积为:");
return length*width;
}
}
class Triangle extends Shape
{
Triangle(final double num,final double num1)
{
super(num,num1);
}
System.out.println("三角形的面积为:");
return(0.5*length*width);
}
public class CalculateArea
{
//protected CalculateArea(){}
public static void main(final String[] args)
{
Shape fObj;
Square sqObj=new Square(10,20);
Triangle trObj=new Triangle(12,8);
fObj=sqObj;
System.out.println(fObj.area());
fObj=trObj;
System.out.println(fObj.area());
}
}
运行时出现需要标识符,什么错误?
{
protected double length;
protected double width;
Shape(final double num,final double num1)
{
length=num;
width=num1;
}
abstract double area();
}
class Square extends Shape
{
Square(final double num,final double num1)
{
super(num,num1);
}
double area()
{
System.out.println("正方形的面积为:");
return length*width;
}
}
class Triangle extends Shape
{
Triangle(final double num,final double num1)
{
super(num,num1);
}
System.out.println("三角形的面积为:");
return(0.5*length*width);
}
public class CalculateArea
{
//protected CalculateArea(){}
public static void main(final String[] args)
{
Shape fObj;
Square sqObj=new Square(10,20);
Triangle trObj=new Triangle(12,8);
fObj=sqObj;
System.out.println(fObj.area());
fObj=trObj;
System.out.println(fObj.area());
}
}
运行时出现需要标识符,什么错误?
return(0.5*length*width);
放在double area(){}里