Please choose all the answers that apply. Select 2 options. A class can extend o
ID: 3704966 • Letter: P
Question
Please choose all the answers that apply. Select 2 options.
A class can extend one class and implements many interfaces
An interface can extend many interfaces
A class can extend one class and many interfaces
A class can implement one class and many interfaces
An interface can extend many classes and interfaces
An interface can implement many classes and interfaces
An interface can implement many interfaces
4 points
QUESTION 10
Consider the following class:
public class A {
public int timesTwo(int x) {
return x + x;
}
}
Which of the following classes inherits from A but replaces the timesTwo() method with a new implementation?
class B extends A {
public int timesTwo (int x) {
return x * 2;
}
}
public class A extends B {
public int timesTwo (int x) {
return x * 2;
}
}
public class B extends A {
public float timesTwo (float x) {
return x * 2.0F;
}
}
public class B extends A {
}
4 points
QUESTION 11
What is the output of compiling and running the following program?
class Category {
Category() { System.out.println("Constructor of Category"); }
}
class SubCategory extends Category {
SubCategory() { System.out.println("Constructor of SubCategory"); }
}
class SubSubCategory extends SubCategory {
SubSubCategory() { System.out.println("Constructor of SubSubCategory"); }
}
public class Tester {
public static void main(String[] args) {
new SubSubCategory();
}
}
None of the mentioned
Constructor of SubSubCategory
Constructor of Category
Constructor of SubCategory
Constructor of SubSubCategory
Constructor of SubSubCategory
Constructor of SubCategory
Constructor of Category
5 points
QUESTION 12
The following program fails to compile, where could possibly be the compilation error(s)? Select 2 options.
class Creature { }
class Bird extends Creature { }
class Falcon extends Bird { }
public class Tester {
public static void main(String[] args) {
Creature c1 = new Creature();
Creature c2 = new Bird();
Bird b1 = (Bird) c1; // Line 1
Bird b2 = (Falcon) c2; // Line 2
Bird b3 = c2; // Line 3
Bird b4 = new Falcon(); // Line 4
Bird b5 = (Bird) new Creature(); // Line 5
Falcon f1 = b4; // Line 6
}
}
Line 3
Line 4
Line 5
Line 6
Line 1
Line 2
4 points
QUESTION 13
What keyword or keywords are used to indicate that a class inherits from another class?
inherits
is a
extends
implements
4 points
QUESTION 14
Which statement(s), inserted independently at the insertion point in the main function, will compile and run successfully? Select 2 options.
class Creature {
String getName() { return "Creature"; }
}
class Bird extends Creature {
String getName() { return "Bird"; }
}
class Falcon extends Bird {
String getName() { return "Falcon"; }
}
public class Tester {
public static Bird getIt(Creature c) {
System.out.println(c.getName());
return (Bird) c;
}
public static void main(String[] args) {
// insert code here
}
}
getIt(new Bird());
getIt(new Falcon());
getIt(new Creature());
getIt(new Object());
4 points
QUESTION 15
What is the result of compiling and running the following code?
class Base {
public Base() { System.out.println("Base"); }
}
public class Derived extends Base {
public Derived() { this("JavaChamp"); System.out.println("Derived"); }
public Derived(String s) { System.out.println(s); }
public static void main(String[] args) {
new Derived();
}
}
JavaChamp
Base
Derived
JavaChamp
Derived
Base
The code will not compile
Base
JavaChamp
Derived
JavaChamp
Derived
A class can extend one class and implements many interfaces
An interface can extend many interfaces
A class can extend one class and many interfaces
A class can implement one class and many interfaces
An interface can extend many classes and interfaces
An interface can implement many classes and interfaces
An interface can implement many interfaces
Explanation / Answer
Question 9
Answer:
A class can extend one class and implements many interfaces
An interface can extend many interfaces
An interface can implement many interfaces
Question 10
Answer:
public class A extends B {
public int timesTwo (int x) {
return x * 2;
}
}
Question 11
Answer:
Constructor of Category
Constructor of SubCategory
Constructor of SubSubCategory
Question 12
Answer:
Line 3
Line 5
Question 13
Answer:
extends
implements
Question 14
Answer:
getIt(new Bird());
getIt(new Falcon());
getIt(new Creature());
Question 15
Answer:
Base
JavaChamp
Derived