没有实例化

源自：10-3 Java 中的抽象类

没有实例化

package math;

public class all {

	public abstract class shape {
		public abstract  void area();
		public abstract  void perimeter(); 
	}
	
	public abstract class circle extends shape {
		double r = 2.2;
	    public void area(){
		 System.out.println("circle area is "+3.14*r*r);
	    }
	    public void perimeter(){
	    	System.out.println("circle perimete is "+2*r*3.14);
	    }
		
	}

	public abstract class rectangle extends shape {
		double a=1.0;
		double b=1.0;
		public void area(){
			System.out.println("rectangle ares is"+a*b);
		}
		public void perimeter(){
			System.out.println("recrangle perimeter is "+2*(a+b));
		}

	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
	    shape area1 = new circle();//这里显示错误，Cannot instantiate the type circle

		area1.perimeter();
	        area1.area();
	    shape area2 = new rectangle();//这里显示错误，Cannot instantiate the type rectangle
		area2.perimeter();
		area2.area();

	}
}

问一下这个情况该怎么解决。找不到解决方法，谢谢

提问者：qq_瞳孔一抹蓝_04076840 2016-12-01 20:49

个回答

AINIforever

2016-12-18 17:43:22

子类不能加abstract修饰符

0
turbo_elaine

2016-12-01 21:23:48

public abstract class shape {
        public abstract  void area();
        public abstract  void perimeter();
    }

    public abstract class circle extends shape {
        double r = 2.2;
        public void area(){
         System.out.println("circle area is "+3.14*r*r);
        }
        public void perimeter(){
            System.out.println("circle perimete is "+2*r*3.14);
        }

    }

    public abstract class rectangle extends shape {
        double a=1.0;
        double b=1.0;
        public void area(){
            System.out.println("rectangle ares is"+a*b);
        }
        public void perimeter(){
            System.out.println("recrangle perimeter is "+2*(a+b));
        }

    }

public class test{
public static void main(String[] args) {
        // TODO Auto-generated method stub
        shape area1 = new circle();//这里显示错误，Cannot instantiate the type circle

        area1.perimeter();
            area1.area();
        shape area2 = new rectangle();//这里显示错误，Cannot instantiate the type rectangle
        area2.perimeter();
        area2.area();

    }
}

0