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();}