Chapter 8 - Code conventions and design

Question 1

this is 80 characters

Answer 1

what is the
maximum line length

Question 2

these are used where more detail is needed to explain the code

Answer 2

describe how
Multi line comments are used

Question 3

describe a
String Literal (“”)

Answer 3

A string created using this method is created in a pool of previously created strings in the Java runtime system. If the string already exists in the pool, the reference is used, otherwise, a new string is created and added to the pool. This process is known as interning and saves memory.

Question 4

this should contain the name of its superclass

Answer 4

what should a
subclass contain within their name

Question 5

What is
**responsibility-driven **
design in programming?

Answer 5

this is the principle that a class should be responsible for manipulating its own data.

This helps to maintain high cohesion by keeping the responsibilities of a class focused and related to one another.

Question 6

A string created using this method is created in a pool of previously created strings in the Java runtime system. If the string already exists in the pool, the reference is used, otherwise, a new string is created and added to the pool. This process is known as interning and saves memory.

Answer 6

describe a
String Literal (“”)

Question 7

this is used in a switch statement to prevent the flow of execution from “falling through” to the next case. This is usually desired to prevent unintended consequences.

Answer 7

What is the
purpose of a break statement in a switch statement?

Question 8

these should be named as:
1. a noun (a word that refers to a person, place, thing, event, substance, or quality)
2. be singular (Animal not Animals)

Answer 8

in 2 points
how should classes be named

Question 9

Chapter 8 quiz

Answer 9

ignore

Question 10

What is
cohesion
in programming?

Answer 10

this is a measure of how strongly related and focused the responsibilities of a class or method are.

it is desirable that this is kept high, as it means that a class or method completes a specific task and is not carrying out too many subtasks.

Question 11

describe
Comparing String Literals with “==”

Answer 11

When comparing these using the “==” operator, they will compare as equal because the Java runtime system will return the reference to the string in the pool of previously created strings.

Question 12

describe why we should be
Comparing Strings with “equals()”

Answer 12

To determine if two string objects contain the same characters, this method should be used instead of “==”.

This method compares the state of the objects, not just their identity.

Question 13

What is the
purpose of a default case in a switch statement?

Answer 13

this in a switch statement is used as a catch-all case and is usually included to handle unexpected input or signal an error.

note:
this should be included with all switch statements

Question 14

describe
Comparing Explicitly Created Strings with “==”

Answer 14

When comparing these using the “==” operator, they may compare as not equal even though they contain the same characters. This is because “==” compares only object identity, not state.

Question 15

these are usually:
1. declared and initialised at the same time
2. at the start of a method or at the start of a block of code

Answer 15

when are
local variables initialised

Question 16

these may be reused through inheritance and composition.
1. Inheritance allows a subclass to reuse the elements of its superclass
2. composition allows a class to have a field of a different class type to form a relationship. (may also be known as a “has a”)

Answer 16

What are the two ways
classes may be reused in object-oriented design?

Question 17

Data hiding and encapsulation are techniques to mitigate this.

1. Data hiding - The use ofaccess modifiersto restrict access tofieldsfrom outside of a class.
   2.** Encapsulation **- The packaging together in an object of data and theoperationsthat can be applied to that data, together with the use ofdata hidingto restrict access toimplementation details.

They ensure that another component of the class cannot be coupled to the implementation of a class, allowing it to be freely modified as long as the public interface remains unchanged.

Answer 17

What are some methods to
mitigate coupling?

Question 18

What is
**change localisation **
in programming?

Answer 18

this is the principle of restricting the amount of code that needs to be changed when maintenance or extension of the source code is required.

The goal is to make changes in a single place for better maintainability.

Question 19

When is a
**refactor **
necessary in programming?

Answer 19

this is necessary when a class or method begins carrying out too many subtasks and is no longer completing a specific task.

This is known as low cohesion, and refactoring can improve cohesion by dividing the responsibilities into smaller, more focused components.

Question 20

some points on these are:
1. used to describe fields
2. used to describe local variables
3. used to describe how single line of code works

Answer 20

describe in 3 points how
Single line comments (//) are used

Question 21

To determine if two string objects contain the same characters, this method should be used instead of “==”.

This method compares the state of the objects, not just their identity.

Answer 21

describe why we should be
Comparing Strings with “equals()”

Question 22

within a class this goes:
1. package statement (not used in M250)
2. importstatements
3. comments about the class
4. fields class (staticorstatic final) variables > instance variables
5. constructors
6. getter and setter methods, in the same order as the corresponding fields are declared
7. other methods.

Answer 22

in a java source file what is the
order of declaration within a class

Question 23

if we have an expression such as this then we should
1. break it on to a new line
2. with the operator as the first character

Answer 23

if we have a long
expression exceeding 80 charcters
how should we deal with it

Question 24

how should
Class (static) variables and methods be accessed

Answer 24

these should always be accessed via the class name they belong to

note:
although it is possible to achieve the same using an instance of the class or using the this keyword. this should be avoided as it is misleading and does not explicitly state that we are accessing a class element

Question 25

What are the two ways
classes may be reused in object-oriented design?

Answer 25

these may be reused through inheritance and composition.
1. Inheritance allows a subclass to reuse the elements of its superclass
2. composition allows a class to have a field of a different class type to form a relationship. (may also be known as a “has a”)

Question 26

these should be:
1. Initialised excusively in the constructor
2. The exception is class (static) and class constants (final static) which will be initialised with declaration

Answer 26

when are
Fields (class and instance variables) initialised

Question 27

What is
Coupling?

Answer 27

this refers to the interdependence of components in a system, meaning that they have a dependency on each other to function.

It’s generally desirable to minimize this, but it is often unavoidable.

Question 28

what is the
maximum line length

Answer 28

this is 80 characters

Question 29

What are 4 examples of
coupling?

Answer 29

this can occur when
1. composition - objects of class P have an instance variable that references an object of class Q
2.** inheritance** - when P is a subclass of Q
3. method invocation coupling - when an object of class P calls a method in an object of class Q
4. object reference coupling - when P has a method that receives or returns an object of class Q

Question 30

these are methods that provide functionality used by two or more methods. By using these, we can reduce duplicate code and improve code reuse.

Answer 30

What are
**helper methods **
in programming?

Question 31

in 2 points
how should classes be named

Answer 31

these should be named as:
1. a noun (a word that refers to a person, place, thing, event, substance, or quality)
2. be singular (Animal not Animals)

Question 32

What are some methods to
mitigate coupling?

Answer 32

Data hiding and encapsulation are techniques to mitigate this.

1. Data hiding - The use ofaccess modifiersto restrict access tofieldsfrom outside of a class.
   2.** Encapsulation **- The packaging together in an object of data and theoperationsthat can be applied to that data, together with the use ofdata hidingto restrict access toimplementation details.

They ensure that another component of the class cannot be coupled to the implementation of a class, allowing it to be freely modified as long as the public interface remains unchanged.

Question 33

how should methods be named

Answer 33

these should be named as:
1. verbs (an action, state, or occurrence)

Question 34

A string can be explicitly created using the “new String()” method. This creates a new string object and is not stored in the pool of previously created strings.

Answer 34

describe
Explicitly Creating a New String

Question 35

decsribe
the principle of
code reuse
in object-oriented design?

Answer 35

this principle of object-oriented design is about designing and writing code in such a way that it can be used and reused in multiple places to improve efficiency, maintainability, and decrease the risk of logic errors.

Question 36

What is the general advice for
using break and continue statements in loops?

Answer 36

It is generally advisable to avoid using these two statements to control the flow of a loop as it can make the loop behavior unclear. Instead, alternative control structures such as if-else statements should be used.

Question 37

It is generally advisable to avoid using these two statements to control the flow of a loop as it can make the loop behavior unclear. Instead, alternative control structures such as if-else statements should be used.

Answer 37

What is the general advice for
using break and continue statements in loops?

Question 38

this refers to the interdependence of components in a system, meaning that they have a dependency on each other to function.

It’s generally desirable to minimize this, but it is often unavoidable.

Answer 38

What is
Coupling?

Question 39

this is necessary when a class or method begins carrying out too many subtasks and is no longer completing a specific task.

This is known as low cohesion, and refactoring can improve cohesion by dividing the responsibilities into smaller, more focused components.

Answer 39

When is a
**refactor **
necessary in programming?

Question 40

if we have a long
expression exceeding 80 charcters
how should we deal with it

Answer 40

if we have an expression such as this then we should
1. break it on to a new line
2. with the operator as the first character

Question 41

this is the principle that a class should be responsible for manipulating its own data.

This helps to maintain high cohesion by keeping the responsibilities of a class focused and related to one another.

Answer 41

What is
**responsibility-driven **
design in programming?

Question 42

these should always be accessed via the class name they belong to

note:
although it is possible to achieve the same using an instance of the class or using the this keyword. this should be avoided as it is misleading and does not explicitly state that we are accessing a class element

Answer 42

how should
Class (static) variables and methods be accessed

Question 43

What is the importance of
** Data hiding and Encapsulation **
in reducing coupling?

Answer 43

these allow the user to know only what a class does (public interface), not how it does it (implementation), ensuring that the implementation of a class cannot be coupled to another component.

This means that the implementation can be freely modified as long as the public interface remains unchanged.

Question 44

this is the process of storing string values by the Java runtime system so that they can be reused efficiently.

Answer 44

describe
Interning

Question 45

When comparing these using the “==” operator, they may compare as not equal even though they contain the same characters. This is because “==” compares only object identity, not state.

Answer 45

describe
Comparing Explicitly Created Strings with “==”

Question 46

What are
**helper methods **
in programming?

Answer 46

these are methods that provide functionality used by two or more methods. By using these, we can reduce duplicate code and improve code reuse.

Question 47

the reason for this is:
methods could be overridden by subclasses if this happens then unexpected behaviour could occur

in general a best practice is to only initialise fields within a constructor and avoid method calls

Answer 47

why should method calls within the constructor be used with caution

Question 48

when are
local variables initialised

Answer 48

these are usually:
1. declared and initialised at the same time
2. at the start of a method or at the start of a block of code

Question 49

these allow the user to know only what a class does (public interface), not how it does it (implementation), ensuring that the implementation of a class cannot be coupled to another component.

This means that the implementation can be freely modified as long as the public interface remains unchanged.

Answer 49

What is the importance of
** Data hiding and Encapsulation **
in reducing coupling?

Question 50

What are
utility methods
in programming?

Answer 50

these are static methods that implement frequently used operations that are of general use to other classes.

They provide a way to reuse code across multiple classes.

Question 51

Chapter 8 glossary quiz

Answer 51

ignore

Question 52

these are static methods that implement frequently used operations that are of general use to other classes.

They provide a way to reuse code across multiple classes.

Answer 52

What are
utility methods
in programming?

Question 53

describe
Explicitly Creating a New String

Answer 53

A string can be explicitly created using the “new String()” method. This creates a new string object and is not stored in the pool of previously created strings.

Question 54

When comparing these using the “==” operator, they will compare as equal because the Java runtime system will return the reference to the string in the pool of previously created strings.

Answer 54

describe
Comparing String Literals with “==”

Question 55

describe how
Multi line comments are used

Answer 55

these are used where more detail is needed to explain the code

Question 56

these should be named as:
1. verbs (an action, state, or occurrence)

Answer 56

how should methods be named

Question 57

this is the principle of restricting the amount of code that needs to be changed when maintenance or extension of the source code is required.

The goal is to make changes in a single place for better maintainability.

Answer 57

What is
**change localisation **
in programming?

Question 58

why should method calls within the constructor be used with caution

Answer 58

the reason for this is:
methods could be overridden by subclasses if this happens then unexpected behaviour could occur

in general a best practice is to only initialise fields within a constructor and avoid method calls

Question 59

when is it acceptable to use short name variables and what are 3 examples of this in use

Answer 59

this naming style is acceptable only with local variables that will shortly go out of scope. some examples:
1. i, j - usually used for integers
2. c, ch - usually used for characters
3. f - usually used for floating points

Question 60

describe
Interning

Answer 60

this is the process of storing string values by the Java runtime system so that they can be reused efficiently.

Question 61

in a java source file what is the
order of declaration within a class

Answer 61

within a class this goes:
1. package statement (not used in M250)
2. importstatements
3. comments about the class
4. fields class (staticorstatic final) variables > instance variables
5. constructors
6. getter and setter methods, in the same order as the corresponding fields are declared
7. other methods.

Question 62

What is the
purpose of a break statement in a switch statement?

Answer 62

this is used in a switch statement to prevent the flow of execution from “falling through” to the next case. This is usually desired to prevent unintended consequences.

Question 63

when are
Fields (class and instance variables) initialised

Answer 63

these should be:
1. Initialised excusively in the constructor
2. The exception is class (static) and class constants (final static) which will be initialised with declaration

Question 64

what should a
subclass contain within their name

Answer 64

this should contain the name of its superclass

Question 65

this in a switch statement is used as a catch-all case and is usually included to handle unexpected input or signal an error.

note:
this should be included with all switch statements

Answer 65

What is the
purpose of a default case in a switch statement?

Question 66

this naming style is acceptable only with local variables that will shortly go out of scope. some examples:
1. i, j - usually used for integers
2. c, ch - usually used for characters
3. f - usually used for floating points

Answer 66

when is it acceptable to use short name variables and what are 3 examples of this in use

Question 67

this can occur when
1. composition - objects of class P have an instance variable that references an object of class Q
2.** inheritance** - when P is a subclass of Q
3. method invocation coupling - when an object of class P calls a method in an object of class Q
4. object reference coupling - when P has a method that receives or returns an object of class Q

Answer 67

What are 4 examples of
coupling?

Question 68

describe in 3 points how
Single line comments (//) are used

Answer 68

some points on these are:
1. used to describe fields
2. used to describe local variables
3. used to describe how single line of code works

Question 69

this principle of object-oriented design is about designing and writing code in such a way that it can be used and reused in multiple places to improve efficiency, maintainability, and decrease the risk of logic errors.

Answer 69

decsribe
the principle of
code reuse
in object-oriented design?

Question 70

this is a measure of how strongly related and focused the responsibilities of a class or method are.

it is desirable that this is kept high, as it means that a class or method completes a specific task and is not carrying out too many subtasks.

Answer 70

What is
cohesion
in programming?

Question 71

A string can be explicitly created using the “new String()” method. This creates a new string object and is not stored in the pool of previously created strings.

Answer 71

describe
Explicitly Creating a New String

Question 72

describe
Explicitly Creating a New String

Answer 72

A string can be explicitly created using the “new String()” method. This creates a new string object and is not stored in the pool of previously created strings.