java编译时出现Cannot instantiate the type Circle

Question

package com.imocc;public class initial   { /** * @param args */ public static void main(String[] args) { Shape do1 = new Circle(); Shape do2 = new Rectangle(); do1.acount1(); do2.acount2(); // TODO Auto-generated method stub } // TODO Auto-generated method stub }

Answer 1

你的Circle类是一个抽象类 在Java中不能直接new 抽象类

Answer 2

package com.imocc;

public abstract class Circle extends Shape {

public int r = 4;

public double x ,y;

public void acount1() {

// TODO Auto-generated method stub

x = 3.14*r*r;

y =2 * 3.14 * r;

System.out.println("圆形的周长是："+ y  +"圆形的面积是："+ x );

}

public void acount2() {

// TODO Auto-generated method stub

}

}

Answer 3

package com.imocc;

public abstract class Shape {

public abstract void acount1();

public abstract void acount2();

}