Skillstorm Intro to Coding - OOP & Java Fundamentals

Question 1

What are classes in Java?

Answer 1

They are blueprints used to define objects

Question 2

What are a few examples of classes?

Answer 2

1. Real-world objects
2. Application components

Question 3

What are the members of a Class in Java?

Answer 3

=> Variables (State)

=> Methods (Behavior)

=> Constructors (Initialization)

Question 4

Given the following code, identify the class body, constructor, method body, and variable.

public class HelloVehicle { 
 int speed; 
 void accelerate() {}

HelloVehicle() {
speed = 0;
}
}

Answer 4

public class HelloVehicle { // class body
 int speed; // variable
 void accelerate() {} //method body

HelloVehicle() {
speed = 0;
} // constructor
}

Question 5

Given a basic HelloWorld class, what’s the best way to write the signature of the main method in Java?

public class HelloWorld {

}

Answer 5

public class HelloWorld {

public static void main(String[] args) {
System.out.println(“Hello World”);
}

}

Question 6

Which is the correct signature of the main method?

1. public static void main(String[] args)
2. static public void main(String[] args)

Answer 6

Both 1. and 2. are correct!!!

Question 7

Label the separate code blocks correctly with following labels: Class, Constructor, Method, and Variable

1. ____________
   public class HelloVehicle{
   2._____________

int speed;

3._____________

void accelerate() {}

4._____________

HelloVehicle(){

speed = 0;

}

}

Answer 7

1. Class

public class HelloVehicle {

2. Variable

int speed;

3. Method

void accelerate() {}

4. Constructor

HelloVehicle(){

speed = 0;

}

}

Question 8

Java is strongly-typed, in other words, you have to state what data type each variable is going to be? True or False

Answer 8

True

Question 9

What are the four data types in Java and their sub-types?

Answer 9

1. Numeric (whole)
   
   1. byte: -128 to 127
   2. short: -32,768 to 32,767
   3. int: -2^31 to 2^31
   4. long: -2^64 to 2^64
2. Numeric (decimal)
   
   1. float: single precision
   2. double: double precision
3. Text
   
   1. char: single character
4. True/False
   
   1. boolean

Question 10

What are non-primitive data types with an example?

Answer 10

Non-Primitive Data Types

1. Any class you want
2. Create your own types

For Example,

Vehicle Class as a variable to be used with an Engine Class

String

1. Multiple characters together

You could string characters together to get a word such as HELLO.

Question 11

In Java arrays, you store multiple values in a _____ _____ variable

Answer 11

single reference

Question 12

Are Java arrays continuous?

Answer 12

Yes, they are a sequential block of memory

Question 13

How do you access the elements of a Java array?

Answer 13

By their index

Question 14

Though values can be different in each index of a Java array, can they also be of a different data type?

Answer 14

No. They have to be the same data type but can be different values

For Example:

If the data type is char, index 0 can have raj, index 1 can have hudek and so on, but index 3 could not have 42 because that is a numeric data type which is different than the original char data type we started out with in index 0 and index 1.

Question 15

What do constructors initialize?

Answer 15

An object’s state

Question 16

Calling a constructor by its new keyword does what?

Answer 16

It creates an object at runtime

Question 17

Does Java provide a default constructor?

Answer 17

Yes, BUT only if you haven’t provided your own

Question 18

Can you define many constructors and if so, what would that be called?

Answer 18

Yes, and it is known as constructor overloading

Question 19

When a class contains a constructor, and you have more than one keyword, what happens when you call the second keyword?

Answer 19

The constructor is invoked to create a brand new object with its own state.

Question 20

If you call the second reference variable (keyword) in a constructor, will the method from the class that acted on the first reference variable work here as well?

Answer 20

No

Question 21

Why can’t you write two constructors that have the same number and type of arguments for the same class?

Answer 21

Because the compiler would not be able to tell them apart!

Question 22

What happens if you don’t provide any constructors for your class?

Answer 22

The compiler automatically provides a no-argument, default constructor for any class without constructors.

Question 23

How do you have variables that are common to all objects?

Answer 23

By using a static modifier

Question 24

What does it mean that a static modifier is called a static field or class variable?

Answer 24

It means they are associated with the class, rather than any with any object.

Question 25

If any object can change the value of a class variable, can class variables also be manipulated without creating an instance of the class?

Answer 25

Yes

Question 26

How are class variables referenced?

Answer 26

By referencing the class name itself. For example: public class Bicycle { private int cadence; private int gear; private int speed; // add an instance variable for the object ID private int id; // add a class variable for the number of Bicycle objects instantiated private static int numberOfBicycles = 0; ... }

Question 27

What can you use to access static fields?

Answer 27

static methods. ## Footnote For example, we could add a static method to the Bicycle class to access the numberOfBicycles static field: public static int getNumberOfBicycles() { return numberOfBicycles; }

Question 28

What can instance methods access directly?

Answer 28

1. instance variables 2. instance methods 3. class variables 4. class methods

Question 29

What can class methods access directly? What can class methods not access directly and what must they use to access these things indirectly? BONUS: Why can't class methods use the "this" keyword?

Answer 29

Can access directly =\> Class variables and class variables. Cannot access directly =\> Instance variables or instance methods What must they use =\> Object reference BONUS =\> Because there is no instance for "this" to refer to.

Question 30

What are the only required elements of a method declaration?

Answer 30

1. Return type 2. Name 3. A pair of parentheses () 4. A body between braces {}

Question 31

More generally, what are the six components of method declarations in order?

Answer 31

1. Modifiers—such as public, private, and others you will learn about later. 2. The return type—the data type of the value returned by the method, or void if the method does not return a value. 3. The method name—the rules for field names apply to method names as well, but the convention is a little different. 4. The parameter list in parenthesis—a comma-delimited list of input parameters, preceded by their data types, enclosed by parentheses, (). If there are no parameters, you must use empty parentheses. 5. An exception list—to be discussed later. 6. The method body, enclosed between braces—the method's code, including the declaration of local variables, goes here.

Question 32

What two components of a method declaration comprise the method signature?

Answer 32

1. The method's name 2. The parameter types

Question 33

What is proper naming convention for methods?

Answer 33

By convention, method names should be a verb in lowercase or a multi-word name that begins with a verb in lowercase, followed by adjectives, nouns, etc. In multi-word names, the first letter of each of the second and following words should be capitalized. For example: run runFast getFinalData

Question 34

Though it's typical for a method to have a unique name within its class, when could they have the same name as other methods (with an example)?

Answer 34

Method overloading or methods with different method signatures. In other words methods within a class can have the same name if they have different parameter lists. For example: public class DataArtist { ... public void draw(String s) { ... } public void draw(int i) { ... } public void draw(double f) { ... } public void draw(int i, double f) { ... } }

Question 35

Give examples of static methods that are created without instances of a class (without an object) using the Math class and the static modifier.

Answer 35

1. Math.random(); 2. Math.pow(2, 31); 3. Math.tan(90); Where Math is the class and random, pow, and tan are the static modifiers.

Question 36

Match the value to the correct variable declaration for Class Vehicle {}: ## Footnote Values =\> 1. false, 2. 'D', 3. "Toyota", 4. 123456789123456789L, 5. 100.1234567890123f, 6. 20000000000 int speed = char fuel = boolean running = long serial = float fuelRemaining = String make =

Answer 36

int speed = 2000000000 char fuel = 'D' boolean running = false long serial = 123456789123456789L float fuelRemaining = 100.1234567890123f String make = "Toyota"

Question 37

Complete the code to call the go method and store the returned value: public class Methods { public static void main(String[] args) { Methods example = new Methods(); int returned = \_\_\_\_\_\_\_\_\_\_\_\_; } public ___ go () { return 510; } }

Answer 37

public class Methods { public static void main(String[] args) { Methods example = new Methods(); int returned = example.go(); } public int go () { return 510; } }

Question 38

Create an object of the Pizza class

Answer 38

Pizza { pizza = new Pizza(); }

Question 39

Complete the code to create an int array of size 3 and store a value in the first position: ## Footnote \_\_\_\_\_\_\_ array = ______ ; \_\_\_\_\_\_\_ = 120;

Answer 39

int[] array = new int[3]; array[0] = 120;

Question 40

The Java programming language is a high-level language that can be characterized by which buzzwords?

Answer 40

* Simple * Object oriented * Distributed * Multithreaded * Dynamic * Architecture neutral * Portable * High performance * Robust * Secure

Question 41

1. What is all source code of the Java programming language written in? 2. What type of files are those source files compiled into? 3. What does the compiling? 4. If the .class file does not contain code that is native to your processor, what kind of code does it contain? 5. Which type of "machine" uses this kind of code? 6. What helps run your application with an instance of the Java Virtual Machine?

Answer 41

1. Plain text files ending with the .java extension 2. .class files 3. Javac compiler 4. bytecodes 5. JVM (Java Virtual Machine) 6. java launcher tool

Question 42

What is the Java Platform?

Answer 42

A platform is the hardware or software environment in which a program runs like Microsoft Windows, Linux, Solaris OS, and Mac OS.

Question 43

What two components does the Java platform have?

Answer 43

1. The Java Virtual Machine 2. The Java Application Programming Interface (API)

Question 44

What is an API?

Answer 44

The API is a large collection of ready-made software components that provide many useful capabilities and are grouped into libraries of related classes and interfaces.

Question 45

What compiles Java code and what executes Java code?

Answer 45

Java Development Kit (JDK) and Java Virtual Machine (JVM) respectively.

Question 46

1. When is a private Java Virtual Machine stack created? 2. What does a Java Virtual Machine stack store? 3. What does the JVM stack hold? . 4. What does the JVM stack play a part in? 5. Does the memory for a JVM stack need to be contiguous? 6. Are JVM stacks fixed or dynamic?

Answer 46

1. The same time as the thread 2. frames 3. variables and partial results 4. method invocation and return 5. No 6. Can be both

Question 47

1. If the computation in a thread requires a larger Java Virtual Machine stack than is permitted, what happens? 2. If Java Virtual Machine stacks can be dynamically expanded, and expansion is attempted but insufficient memory can be made available to effect the expansion, or if insufficient memory can be made available to create the initial Java Virtual Machine stack for a new thread, what error is thrown?

Answer 47

1. Java Virtual Machine throws a StackOverflowError 2. OutOfMemoryError

Question 48

1. What is a JVM heap? 2. Is it shared among all Java Virtual Machines? 3. Is the JVM heap fixed, expandable, or contractible? 4. Does the JVM heap memory need to be contiguous? 5. If a computation requires more heap than can be made available by the automatic storage management system, what error is thrown?

Answer 48

1. The run-time data area from which memory for all class instances and arrays is allocated. 2. Yes 3. All of the above 4. No 5. OutOfMemoryError

Question 49

What can a JVM stack contain?

Answer 49

* Methods calls * Variables declared in methods * Reference variables * Cleaned up as method completes

Question 50

What does a Heap contain or hold?

Answer 50

* Objects * Instance variables * JVM cleans up objects not in use

Question 51

What is encapsulation for?

Answer 51

1. Wrapping related state/behavior in a single unit 2. Protecting class members from undesirable Access

Question 52

Why do programmers bundle groups of related types into packages?

Answer 52

1. To make types easier to find and use 2. To avoid naming conflicts 3. To control access

Question 53

What does "types" in encapsulation refer to?

Answer 53

1. classes 2. interfaces 3. enumerations 4. annotation types

Question 54

Why should you bundle classes and interface?

Answer 54

* You and other programmers can easily determine that these types are related * You and other programmers know where to find types that can provide graphics-related functions * The names of your types won't conflict with the type names in other packages because the package creates a new namespace * You can allow types within the package to have unrestricted access to one another yet still restrict access for types outside the package

Question 55

1. Packages are folders that bundle _____ classes. 2. Typically "reverse" domain name =\> \_\_\_\_\_.example.project 3. Packages provide a fully-qualified _____ name which helps avoid naming \_\_\_\_\_ 4. Packages are a _____ structure 5. The first line of a class must be the _____ statement 6. You can _____ classes into another class

Answer 55

1. related 2. com.example.project 3. class, collisions 4. hierarchical 5. package 6. import

Question 56

1. What do access level modifiers determine? 2. How many levels of access control? 3. What is top-level access control? 4. What is member-level access control?

Answer 56

1. The determine whether other classes can use a particular field or invoke a particular method 2. Two 3. public, or package-private (no explicit modifier) 4. public, private, protected, or package-private (no explicit modifier)

Question 57

# Fill in Modifiers: Access Levels Modifier Class Package Subclass World \_\_\_\_\_ Y Y Y Y \_\_\_\_\_ Y Y Y N \_\_\_\_\_ Y Y N N \_\_\_\_\_\_ Y N N N

Answer 57

Access Levels ## Footnote Modifier Class Package Subclass World public Y Y Y Y protected Y Y Y N no modifier Y Y N N private Y N N N

Question 58

Access Modifiers cont. 1. What do access modifiers do? 2. What can most access modifiers be applied to? 3. Three default modes of access modification? 4. What are some common terms for having no modifier? 5. What does public access modifier do? 6. What does protected access modifier do? 7. What does no modifier do? 8. What does private access modifier do?

Answer 58

1. Restrict visibility to class members 2. Classes, Methods, Variables, Constructors 3. Public, Protected, and Private 4. Default and/or Package Private 5. Accessible anywhere in the application 6. Accessible within the package and any subclasses 7. Accessible only within the package 8. Accessible only within the class

Question 59

1. What does Variable Scope affect? 2. What are the four Variable Scopes in Java?

Answer 59

1. Visibility of variable in a class and Lifespan of the variable 2. Class Variables (static), Instance Variables, Local Variables, and Block-scope Variables

Question 60

Class Variables What are three characteristics of Class Variables?

Answer 60

1. Variables are declared with the static modifier 2. Declared in the class body 3. Variables initialized when the class loads (No instance is needed) 4. All instances share Class Variables Example: class Person { st

Question 61

Instance Variables What are characteristics of Instance Variables?

Answer 61

1. Each new object has its own 2. Declared in the class body 3. Objects are cleaned up when no longer referenced 4. Marked for garbage collection when the object is class Person { static Planet planet; \<======== This is the Class Variable int age; \<================= This is the Instance Variable }

Question 62

Local Variables What are characteristics of Local Variables?

Answer 62

1. Declared in the method body 2. Declared as a method parameter 3. Marked for garbage collection when the method ends 4. Available anywhere in the method public void code(Computer pc) { \<========The declaration is also part of the Local Variable IDE ide = new IDE(); \<======= This is the Local Variable }

Question 63

Block-Scope What are characteristics of Block-Scope Variables?

Answer 63

1. Declared within a block of code (if statements, loops, try-catch blocks etc.) 2. Marked for garbage collection after the block ends 3. Not accessible in the method, only that block Example: public void jump(boolean b) { if(b){ int height = 2; \<==== Can't be used anywhere else inside the jump method }

Question 64

Label the four different scopes on this code: ## Footnote ``` class Person { // \_\_\_\_\_\_\_\_ int age; // \_\_\_\_\_\_\_\_ static String planet; // \_\_\_\_\_\_\_\_ public void move(int distance) { { // \_\_\_\_\_\_\_\_\_\_ int x = 10; distance = 10; } x = 9; distance = 10; } } ```

Answer 64

``` class Person { // instance variable int age; // class variable static String planet; // local variable public void move(int distance) { { // block-scope variable int x = 10; distance = 10; } x = 9; distance = 10; } } ```

Question 65

What is Inheritance?

Answer 65

Passing down state and behavior from one class to another

Question 66

What are four characteristics of Inheritance and an example of how inheritance looks?

Answer 66

1. Has Super-class / sub-class relationship 2. It is a parent-child relationship 3. It facilitates code reusability 4. It allows for extensibility to change existing classes Example: class Cucumber {} class Pickle extends Cucumber {}

Question 67

1. How many superclasses can an Object have? 2. How many superclasses can a class have? 3. If there is no explicit superclass, what does a class become the subclass of?

Answer 67

1. None 2. Only one direct superclass (single inheritance) 3. Every class is then implicitly a subclass of Object

Question 68

What is a descended class?

Answer 68

Classes can be derived from classes that are derived from classes that are derived from classes and so on, and ultimately derived from the topmost class, Object. The class that is descended from all the classes in the inheritance chain stretching back to the object is the descended class.

Question 69

What does a subclass inherit from its superclass?

Answer 69

All the members which include the fields, methods, and nested classes.

Question 70

What does a subclass not inherit from its superclass?

Answer 70

Constructors are not members, and therefore not inherited by subclasses, but the constructor of the superclass can be invoked from the sublcass

Question 71

Are all classes in the java platform descendants of Object?

Answer 71

Yes

Question 72

True or False: 1. The inherited fields can not be used directly, unlike all other fields... 2. Though not recommended, you can declare a field in the subclass with the same name as the one in the superclass, thus hiding it... 3. You can declare new fields in the subclass that are not in the superclass... 4. The inherited methods need to be modified before they can be used... 5. You can not write a new instance method in the subclass that has the same signature as the one in the superclass... 6. You can write a new static method in the subclass that has the same signature as the one in the superclass... 7. You can not declare new methods in the subclass that are not in the superclass... 8. You can write a subclass constructor that invokes the constructor of the superclass, either implicitly or by using the keyword super...

Answer 72

1. False 2. True 3. True 4. False, they can be used directly 5. False (new method will override the method in the superclass) 6. True (this hides method in the superclass) 7. False, you can declare new methods in the subclass that are not in the superclass 8. True

Question 73

If your method overrides one of its superclass's methods, how can you invoke the overridden method?

Answer 73

By using the keyword super Example: public class Superclass { public void printMethod() { System.out.println("Printed in Superclass."); } } Here is a subclass, called Subclass, that overrides printMethod(): public class Subclass extends Superclass { // overrides printMethod in Superclass public void printMethod() { super.printMethod(); \<==== PAY ATTENTION TO THIS!!! System.out.println("Printed in Subclass"); } public static void main(String[] args) { Subclass s = new Subclass(); s.printMethod(); } }

Question 74

What keyword do you use to invoke a superclass's constructor?

Answer 74

super(); or super(parameter list);

Question 75

What is constructor chaining?

Answer 75

If a subclass constructor invokes a constructor of its superclass, either explicitly or implicitly, there will be a whole chain of constructors call, all the way back to the constructor of Object.

Question 76

How can you refer to any member of the current object from within an instance method or a constructor?

Answer 76

By using the "this" keyword.

Question 77

Use the this keyword to call another constructor in the same class below: ## Footnote public class Rectangle { private int x, y; private int width, height;

Answer 77

public Rectangle() { this(0, 0, 1, 1); } public Rectangle(int width, int height) { this(0, 0, width, height); } public Rectangle(int x, int y, int width, int height) { this. x = x; this. y = y; this. width = width; this. height = height; } ... }

Question 78

Variable Shadowing * Variables can be shadowed * Parent defines variable x and so does Child * Child variable x shadows the Parent variable * Variables can be distinguished super and this * Local variables can shadow instance variables If you have a Parent with int x = 10; and A Child with with int x = 5; 1. How do you print Parent variable? 2. How do you print the Child variable?

Answer 78

1. super.x 2. this.x

Question 79

Constructor Chaining 1. What does every class in Java inherit from? 2. What is implied if you don't define a superclass? 3. What are the two options the first line of a constructor must be a call to? 4. Does calling a constructor cause a chain of constructors to fire?

Answer 79

1. java.lang.Object 2. extends Object is implied 3. super() or this() 4. Yes

Question 80

# Fill in the Blank: class Example { public static void main(String[] args) { Example ex = new Example ("Java"); } public Example () { System.out.println("Hello World"); } public Example(String word) { WHAT GOES HERE TO PRINT "Hello World" TO THE SCREEN? } }

Answer 80

this();

Question 81

Complete the code to inherit the state and behavior from the Cucumber class into the Pickle class. ## Footnote class Pickle ______ Cucumber { }

Answer 81

extends

Question 82

Complete the code to store the value of the parameter into the instance variable. ## Footnote class Child extends Parent { int x = 5; public void setX(int x) { \_\_\_\_\_\_\_\_ \<=== Fill in the correct code here } }

Answer 82

this.x = x;

Question 83

Abstraction: * Building partial or incomplete classes (shapes, for example, are hard to define) * Create a foundation for other classes (but we can define the area the shape will take up, for example, double area ()) * Generalizations group shared functionality into a parent * Specializations extend them to further define behavior 1. Abstraction is defined as what? 2. What do we use to do abstraction in Java?

Answer 83

1. Creating classes without knowing how they're to be implemented 2. Abstract classes and interfaces

Question 84

1. Can an abstract class include abstract methods? 2. Can an abstract class be instantiated? 3. Can an abstract class be subclassed? 4. How is an abstract method declared? 5. If a class includes abstract methods, what must be done with the class? 6. When an abstract class is subclassed, does anything have to be done with the class? 7. If a method in an interface is not declared or static, then what are they classified as? 8. Is the abstract modifier used with interface methods?

Answer 84

1. It can include or not include abstract methods 2. Abstract classes cannot be instantiated 3. Abstract classes can be subclassed 4. Abstract methods are declared without an implementation (without braces, and followed by a semicolon), like this: abstract void moveTo(double detaX double deltaY); 5. When a class includes abstract methods, then the class itself must be declared abstract, as in: public abstract class GraphicObject {} 6. No, the subclass usually provides implementations for all of the abstract methods in its parent class. However, if it does not, then the subclass must also be declared abstract. 7. Then they are implicitly abstract 8. No, abstract modifiers are not used with interface methods.

Question 85

When do you use abstract classes versus? When do you use interfaces?

Answer 85

Abstract Classes: * You want to share code among several closely related classes. * You expect that classes that extend your abstract class have many common methods or fields, or require access modifiers other than public (such as protected and private). * You want to declare non-static or non-final fields. This enables you to define methods that can access and modify the state of the object to which they belong. Interfaces: * You expect that unrelated classes would implement your interface. For example, the interfaces Comparable and Cloneable are implemented by many unrelated classes. * You want to specify the behavior of a particular data type, but not concerned about who implements its behavior. * You want to take advantage of multiple inheritance of type.

Question 86

True or False: 1. Abstract classes are not partially built classes... 2. Methods defined abstract do need a method body... 3. May have zero to many abstract methods... 4. Class does not have to be declared abstract to allow abstract methods... 5. Abstract classes cannot be instantiated... 6. Abstract classes cannot extend other abstract classes...

Answer 86

1. False (they are partially built classes) 2. False (they do not need a method body) 3. True 4. False (they must be declared) 5. True 6. False (they can extend other abstract classes)

Question 87

Interfaces 1. Are interfaces purely 100% abstract? 2. What do interfaces define that classes can follow? 3. How do APIs utilize interfaces? 4. Interface methods are implicitly what? 5. Can classes implement more than one interface? 6. Abstract class defines what versus what an interface defines?

Answer 87

1. Yes they are 2. They define a Contract 3. They establish a Behavior for an API 4. public abstract 5. They can implement many interfaces 6. Abstract class defines =\> What it is, while Interface defines =\> What it does.

Question 88

What does an interface declaration consist of including an example?

Answer 88

* modifiers * the keyword interface * the interface name * a comma-separated list of parent interfaces (if any) * and the interface body For example: public interface GroupedInterface extends Interface1, Interface2, Interface3 { double E = 2.718282; void doSomething (int i, double x); int doSomethingElse(String s); }

Question 89

Interface Body 1. What can the interface body contain? 2. What is an abstract method within an interface followed by? 3. What is an abstract method within an interface not followed by? 4. Default methods are defined by what? 5. Static methods are defined by what? 6. Are all abstract, default and static methods in an interface implicitly public? Which means you can omit what? 7. Can interfaces contain constant declarations? 8. Constant values defined in an interface are implicitly what? Which means you can omit what?

Answer 89

1. abstract methods, default methods, and static methods 2. semicolon 3. braces (an abstract method does not contain an implementation) 4. default modifier 5. static keyword 6. Yes. You can omit the public modifier 7. Yes 8. public, static, and final. You can omit these modifiers.

Question 90

Complete the code so that the class compiles ## Footnote interface Drawable { public void draw(); } class Rectangle ______ Drawable { public void draw() {} }

Answer 90

implements

Question 91

Complete the code so that the class compiles ## Footnote \_\_\_\_\_\_ class Shape { abstract double area(); }

Answer 91

abstract

Question 92

Polymorphism: 1. Is it the ability for objects to be used strictly as one type? 2. Does polymorphism allow for covariance and virtual method invocation? 3. Do covariants have to pass the HAS-A check?

Answer 92

1. False. It is the ability for objects to be used flexibly 2. Yes or True 3. No or False. Covariant assignment must pass the IS-A check

Question 93

Method Overriding: * If your method signature in the child class is the same as the signature in the parent class, is that method overriding? class Animal void **speak()** {} class Dog void **speak()** {} * Method overriding stops us from changing behavior in a specialized class? * Will the right method be called, no matter the reference type and why? * Overriden method doesn't take precedence over superclass method?

Answer 93

1. Yes 2. False. The point of method overriding is allowing us to change behavior in a specialized class 3. Yes, because of Virtual Method Invocation 4. False. Method overriding does take precedence over the superclass method, but not that only non-static methods can be overriden.

Question 94

In method overriding, if you don't have the same method name and parameter, is it still method overriding?

Answer 94

No. If you have the same method name, but a different parameter, that is method overloading.

Question 95

# Fill in the correct code for Abstraction: abstract class Furniture{} class Chair extends Furniture{} public class Store { public static void main(String[] args) { \_\_\_\_\_ chair = new \_\_\_\_\_ } }

Answer 95

Chair Chair();

Question 96

Complete the code so that it compiles and prints Meow Bark Meow public class Kennel { public static void main(String[] args) { pets[0] = \_\_\_\_ pets[1] = \_\_\_\_ pets[2] = \_\_\_\_ for (Animal a : pets) { a.speak(); } } } abstract class Animal{ abstract void speak(); } class Dog _____ \_\_\_\_\_{ void speak() { System.out.printIn("Bark"); } } class Cat _____ \_\_\_\_\_ { void speak() { System.out.printIn("Meow"); } }

Answer 96

new Cat(); new Dog(); new Cat(); extends Animal extends Animal

Question 97

Complete the code so that the application prints "p": ## Footnote public class Override { public static void main(String[] args) { Poppable obj = ____ \_\_\_\_ obj.pop(); } } class Poppable { public void pop() { System.out.printIn("Pop"); } } class Balloon extends Poppable { public void pop() { System.out.printIn("POP!"); } } class Bubble extends Poppable { public void pop() { System.out.printIn("p"); } }

Answer 97

new Bubble();