• abstract 相关问题

    abstract 相关问题

    题目一

    什么是抽象类

    1. A class with no methods
    2. A class with no concrete subclasses
    3. A class with at least one undefiend message
    4. None of above

    答案是 4 我们是可以定义一个抽象空类的

    1. abstract class emptyAb {}

    题目二

    1. abstract class Base{
    2.     abstract public void myfunc();
    3. }
    5. public class Abs extends Base{
    6.     public static void main(String argv[]){
    7.         Abs a = new Abs();
    8.         a.amethod();
    9.     }
    11.     public void amethod(){
    12.         System.out.println("A method");
    13.     }
    14. }

    运行的结果

    1. 输出 A method
    2. The code will compile but complain at run time
    3. The compiler will complain errors in Abs class

    答案是 3