[开课学院]: 资电学院 [开课系所]: 资讯 [课程名称]: 物件导向设计 [老师名称]: 张贵忠 老师 [开课学期]: 97-1 [类型]: 97-1期末考 Totally 100 points 1. (Basic Concepts - 20 pts) Just a brief explanation (a) Event-driven programming (b) Polymorphism (c) Base class / Derived class (d) Abstract class 2. (Polymorphism - 10 pts) Please describe what is late binding, and what is early binding? Which one of above techniques is used for java to achieve Polymorphism? 3. (Inheritance - 10 pts) What are the differences between overloading and overriding? 4. (Inner Class - 10 pts) What is inner class? What are the advantages of using inner class? 5. (Polymorphism - 15 pts) What are the outputs of the following codes? ------------------------------------------------------------------------------ public class A ( String msg; public A() { this("I'm class A"); } public A(String msg) { this.msg = msg; } public void sayHello() { System.out.println("A:" + msg); } } public class B extends A{ public B() { super("I'm class B"); } public void sayHello() { System.out.println("B:" + msg); } } ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ public class C { public static void main(String[] args) { A obj1 = new A(); B obj2 = new B(); C mainObj = new C(); mainObj.showMessage(obj1); mainObj.showMessage(obj2); } public void showMessage(A member) { member.sayHello(); } } ------------------------------------------------------------------------------ 6. (The final Modeifier - 15 pts) What are the meaning of final class, final variable, final method respectively? 7. (Access Modifiers - 20 pts) Given the following codes, and some compile-time errors exist in this program. Please precisely indicate the the line numbers of error statements in the program. (Remember to briefly explain why the indicated statement is error.) ------------------------------------------------------------------------------ 1 package mypackage; 2 public class A { 3 public int v1; 4 protected int v2; 5 int v3; 6 private int v4; 7 } ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ 8 package mypackage; 9 public class B { 10 public B() { 11 A obj1 = new A(); 12 obj1.v1 = 10; 13 obj1.v2 = 10; 14 obj1.v3 = 10; 15 obj1.v4 = 10; 16 } 17 } ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ 18 package mypackage; 19 public class C extends A { 20 public C() { 21 v1 = 10; 22 v2 = 10; 23 v3 = 10; 24 v4 = 10; 25 } 26 } ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ 27 import mypackage.A; 28 public class D extends A { 29 public D() { 30 v1 = 10; 31 v2 = 10; 32 v3 = 10; 33 v4 = 10; 34 } 35 } ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ 36 public class E { 37 public E() { 38 A obj1 = new A(); 39 obj1.v1 = 10; 40 obj1.v2 = 10; 41 obj1.v3 = 10; 42 obj1.v4 = 10; 43 } 44 } ------------------------------------------------------------------------------ -- 我从来没讨厌过记者，只是不喜欢一部份自称记者的寄生虫而已。我讨厌的是对可能受到政 治压力的事避而不提，却专写那些会伤害一般市民的隐私及名誉的记者；更过份一点，成为 当权者的利益代辩人的家伙而已。 杨威利　银河英雄传说 --

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