Chapter 7

Question 1

What are the four basic activities of software creation?

Answer 1

1. establishing the requirements
2. creating a design
3. implementing the code (the easiest part actually)
4. testing the implementation

Question 2

What are software requirements?

Answer 2

The list of software requirements is list that specifies WHAT the program should do. These requirements must be analyzed and critiqued, leading to other requirements.

Question 3

What is the design of a program?

Answer 3

The design specifies the WAY the program is going to accomplish its requirements.
The design should break every requirement into small pieces and manageable pieces.
The design also structures classes and object and the way they will interact with the program.

Question 4

What is implementation in a program?

Answer 4

The implementation is the process of TRANSLATING design into a code.

Question 5

What is testing in a program?

Answer 5

Testing is process in which the software is put under any possible circumstance to CHECK whether the requirements will be fulfilled and what errors or vulnerabilities can the program have.
Debugging will be the process in which problems and errors will be addressed and solved.

Question 6

What is the lengthiest process in software development?

Answer 6

Maintenance: it will exist as long as the program does.

Question 7

What is the build-and-fix approach of software development?

Answer 7

It’s the act of building a program that hasn’t been well structured and that with errors and bad design is attempted to be fixed piece by piece when the code is already in place.

Question 8

What does persistence mean?

Answer 8

Persistence is the concept of an object remaining stored in memory even after the termination of a program that used it.

Question 9

What is the difference between a normal method and a stiatic method?

Answer 9

A normal method is invoked by calling it on an object of class containing the method.

A static method is one that can be invoked by referencing the class name.

Question 10

What is the difference between a normal variable and a static variable?

Answer 10

A normal variable is different for every object of the class.

A static variable is a variable that is shared across all objects of a class. This doesn’t mean that the variable is a constant, but it means that every instance of the class refers to the same variable: changing it in one object will change it for every other class as well.

Question 11

Sometimes static methods cannot reference instance variables. Why?

Answer 11

Static methods cannot reference instance variables, before an object has been created, as the referenced variables start to exist only with the existence of an object.

Question 12

What kinds of variables and methods can the main method of any class reference?

Answer 12

The main method is static and can refer to static or local variables and static methods. The main method cannot refer to instance variables and non-static methods, unless its variables or non-static methods are called thorugh referencing the object.

Question 13

What is a dependency between classes?

Answer 13

A dependency means, that a class relies on another in some way, usually by invoking methods of the other.

Question 14

What is an aggregate object?

Answer 14

An aggregate object is made up of other objects, whose references are stores as instance variables.

Example:
public class Student {

private String firstName, lastName ; ok
private Address homeAddress, schoolAddress;
…
}

public class Address {
....
}

Question 15

What is a Java interface? How is it instantiated?

Answer 15

In Java, an interface is a collection of abstract methods and constants.
An interface cannot be instantiated.
It looks something like this:

public interface Doable  {
public void doThis();
public int doThat();
...
}

Question 16

What is an abstract method?

Answer 16

An abstract method is a method header without a method body.

These methods have public visibility by default.

Question 17

What happens if a class declaration implements an interface?

Answer 17

If a class declares taht it implements an interface, it must define all methods in the interface (by putting a body in it).

Question 18

What variables can an interface contain?

Answer 18

An interface can contain constants.

public static final int…

Question 19

Can multiple classes implement the same interface?

Answer 19

Yes.

Question 20

Can a class implement multiple interfaces?

Answer 20

Yes: all method listed in the interfaces will have to be declared.

Question 21

The Comparable interface has the method compareTo. How does it work?

Answer 21

compareTo confronts in a lexicographical way two strings and returns a negative value is the first is smaller than the second, 0 if they’re equal and a positive value if the first is greater than the second

Question 22

What is the Iterator interface? How is it implemented?

Answer 22

An iterator is an object that provides a means of processing a collection of objects one at a time.

An iterator is created formally by implementing the Iterator interface, which contains three methods:

• The hasNext method returns a boolean result
• The next method returns the next object in the iteration
• The remove method removes the last object returned by the next method.

Question 23

What is the Iterable interface?

Answer 23

The Iterable interface establishes that an object provides an iterator.

In other words, an Iterable interface has a method called iterator() that returns an Iterator object.

Question 24

What is the difference betwen Iterator and Iterable?

Answer 24

An Iterator has methods that perform an iteration. An Iterable object provides an iterator on request.

Question 25

What is the syntax of an enumerated type declaration?
How do the elements of an enumerated type behave?
What are behaviours can an enumerated type have?

Answer 25

Example:
enum Season {winter, spring, summer, fall}

The elements of an enumerated type are stored as objects. Like:
Season time = Season.fall;

As an enumerated type is a class, it can act like it. It can have instance variables and methods.
Like:
public enum Season {

winter(“December through February”),
…

private String span;
...
public String getSpan() {
return span;
}

Question 26

What is the difference betwen putting a primitive data type and an object as a parameter?

Answer 26

With primitive data types, the COPY of the actual parameter is stored inside the formal parameter.

When putting an object reference as a parameter, the ACTUAL REFERENCE is copied into the formal parameter, making actual and formal parameter alieases of each other.

This requires a specific care to the parameters.

Question 27

What is method overloading?

Answer 27

Method overloading consists in defining two or more method with the same name, on the condition that their signature is different.

The signature of a method is the collection of formal parameters. Their data type, their number of data and its order.

With different signatures, the compiler knows to which “method” refer by reading the arguments put into the method header.

If the signatures are not distnguishable one from the other, the compiler will signal an error.

The return type is not part of the signature.

Question 28

What is the goal of testing?

Answer 28

The goal of testing is to find errors. The more errors we find, the stronger is our program.

Question 29

What is a test case?

Answer 29

A test case is a set of input and user actions, couples with expected results.

Question 30

What is defect testing? And regression testing?

Answer 30

Defect testing is done with the objective of finding errors.
Regression testing is done after a set of errors has been fixed, checking whether others errors have not been introduced.

Question 31

What is black-box testing?

Answer 31

Black-box testing consists in running numerous test cases without considering the internal logic. They’re based on input and ouput.

Such testing is helped usually with the introduction of equivalence categories. Two inputs of the same category shoud produce similar results.

Question 32

What is white-box testing?

Answer 32

White-box testing focuses on the internal structure of the code.
This is done by analyzing the code.

Question 33

What is a review / inspection / walkthrough?

Answer 33

It’s the process in which several people examine a design document or a section of code.

Question 34

What are wizards?

Answer 34

Wizards are user-friendly GUI designs that walks a user through a process.

Question 35

What are the events that interact with the mouse?

Answer 35

MouseEvent -> event
setOnMouse\_\_\_\_\_\_\_:
- Pressed
- Released
- Clicked
- Entered
- Exited
- Moved
- Dragged

Question 36

What are the events that interact with keys?

Answer 36

getCode returns the key that was pressed

setOnKey_____:

• Pressed
• Released
• Typed

Question 37

What is rubberbanding?

Answer 37

Rubberbanding consists in drawing a shape into place with the mouse