INTRODUCTION TO JAVA PROGRAMMING教学（华南理工）TEST10.docVIP

1 Object-oriented programming allows you to derive new classes from existing classes. This is called ____________. A. encapsulation B. inheritance C. abstraction D. generalizationB 2 Which of the following statements are true? A. A subclass is a subset of a superclass. B. A subclass is usually extended to contain more functions and more detailed information than its superclass. C. class A extends B means A is a subclass of B. D. class A extends B means B is a subclass of A. 3 Suppose you create a class Cylinder to be a subclass of Circle. Analyze the following code:class Cylinder extends Circle {??double length;??Cylinder(double radius) {?????Circle(radius);??}} A. The program compiles fine, but you cannot create an instance of Cylinder because the constructor does not specify the length of the cylinder. B. The program has a compile error because you attempted to invoke the Circle classs constructor illegally. C. The program compiles fine, but it has a runtime error because of invoking the Circle classs constructor illegally. 4 Analyze the following code:public class Test extends A { ??public static void main(String[] args) {????Test t = new Test();????t.print();??}}class A {??String s;??A(String s) {????this.s = s;??}??public void print() {????System.out.println(s);??}} A. The program does not compile because Test does not have a default constructor Test(). B. The program has an implicit default constructor Test(), but it cannot be compiled, because its super class does not have a default constructor. The program would compile if the constructor in the class A were removed. C. The program would compile if a default constructor A(){ } is added to class A explicitly. D. The program compiles, but it has a runtime error due to the conflict on the method name print. 5 What is the output of running class C?class A {??public A() {????System.out.println(??????The default constructor of A is invoked);??}}class B extends A {??public B() {????Sys