Flashcards in Quiz 5 (incomplete) Deck (8)
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1
You can declare two variables with the same name in ________.
different methods in a class
2
Object-oriented programming allows you to derive new classes from existing classes. This is called ________.
inheritance
3
Which of the following statements are true? (Choose two.)
A subclass is usually extended to contain more functions and more detailed information than its superclass.
"class A extends B" means A is a subclass of B.
4
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);
}
}
The program has a compile error because you attempted to invoke the Circle class's constructor illegally.
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() {
System.out.println("The default constructor of B is invoked");
}
}
public class C {
public static void main(String[ ] args) {
B b = new B();
}
}
"The default constructor of A is invoked""The default constructor of B is invoked"
6
Analyze the following code:
public class Test {
public static void main(String[ ] args) {
B b = new B();
b.m(5);
System.out.println("i is " + b.i);
}
}
class A {
int i;
public void m(int i) {
this.i = i;
}
}
class B extends A {
public void m(String s) {
}
}
The method m is not overridden in B. B inherits the method m from A and defines an overloaded method m in B.
7
Given the following code, find the compile error. (Choose two.)
public class Test {
public static void main(String[ ] args) {
m(new GraduateStudent());
m(new Student());
m(new Person());
m(new Object());
}
public static void m(Student x) {
System.out.println(x.toString());
}
}
class GraduateStudent extends Student {
}
class Student extends Person {
public String toString() {
return "Student";
}
}
class Person extends Object {
public String toString() {
return "Person";
}
}
m(new Person()) causes an error
m(new Object()) causes an error
8
