college/Summer-2024/CS-3443/Slides/txt/04_Java-Best-Practices.txt

Application
Programming
Hend Alkittawi

More on Java Classes
Best practices for Creating Java
Classes

BEST PRACTICES FOR CREATING JAVA CLASSES
STYLE
- identifier naming
- indentation

CONSTRUCTORS
- Ways to instantiate
objects

METHODS
- getters and setters
- equals()
- toString()

JAVADOC
- “special” Java
documentation

STYLE
visibility

type

class name

public class MyClass {
// attributes
private int intVar;
visibility

type

variable name

// methods
public void myMethod(String myString){
visibility

}

}

return
type

method
name

parameter parameter
type
name

METHODS
-

The syntax (rules) for declaring a method
visibility returnType methodName(parameterList)
-

visibility determines access
-

-

returnType is the type of data this method returns
-

-

public (all can access) or private (just this class can access)
if nothing is returned, use the keyword void

methodName starts with a lowercase word
-

it uses uppercase for the first letter of each additional word
(this is called “camel case”)

-

parameterList is any data we need to pass to the method
-

The ordering must be followed exactly

METHODS
-

Getter and setter methods are used to get and set the
value of the attributes.
-

Getters retrieve the value only

-

Setters update the value only

public class Account {
private double balance;
private String name;
public void setBalance( double balance ){
this.balance = balance;
}
public double getBalance(){
return this.balance;
}
// add a getter and a setter for name
}

● to use the class and its methods
public static void main(String[] args){
Account myAccount = new Account();
myAccount.setBalance(1000.0);
double balance = myAccount.getBalance();
}

METHODS
-

toString() method returns a String representation of objects.
An example of a toString() method for the Account class:

public class Account {
private double balance;
private String name;
public void setBalance( double balance ){
this.balance = balance;
}
public double getBalance() {
return this.balance;
}
// … getter and a setter for name
public String toString() {
return "Account info: name: " + name
+ " with balance: " + balance;
}
}

● to use the class and its methods
public static void main(String[] args){
Account myAccount = new Account();
myAccount.setName("Sam Adams");
myAccount.setBalance(1000.0);
System.out.println( myAccount );
}

METHODS
-

equals() method provides a way for users to compare instances
of your object to other instances. This also gives you control
over what is relevant to differentiate your objects.

-

● to use the class and its methods

private double balance;
private String name;

public static void main(String[] args){
Account myAccount = new Account();
Account yourAccount = new Account();
myAccount.setName(“Mia”);
myAccount.setBalace(10);
yourAccount.setName(“Ken”);
yourAccount.setBalance(100);
boolean check =
myAccount.equals(yourAccount);
}

public class Account {

public void setBalance( double balance ) {
this.balance = balance; }
public double getBalance() {
return this.balance; }
public String toString() {
return "Account info: name: " + name
+ " with balance: " + balance; }
public boolean equals( Account account2 ) {
return this.getName().equals( account2.getName());}
}

IMPORTANT

●

== is used for primitive types only
○

●

Objects define an object-method called equals()
○

●

2 == 5

objA.equals(objB);

Core: Drawing Memory Models with Objects - Memory Models, Scope,
and Starting the Project | Coursera

public class Account {
private double balance;
private String name;
public void setBalance( double balance ) {
this.balance = balance; }
public void setName( String name ) {
this.name = name; }

yourAccount

myAccount

name

name

balance

balance

public double getBalance() {
return this.balance; }
public String getName() {
return this.name; }
public boolean equals( Account account2 ) {
return this.getName().equals( account2.getName());
}
public String toString() {
return "Account info: name: " + name
+ " with balance: " + balance; }
}

public static void main(String[] args){
Account myAccount = new Account();
Account yourAccount = new Account();
myAccount.setName("Mia");
myAccount.setBalace(10);
yourAccount.setName("Ken");
yourAccount.setBalance(100);
boolean check =
myAccount.equals(yourAccount);
}

CONSTRUCTORS
-

Java requires a constructor call for every object that is created.

-

The keyword new creates a new object of a specified class by
calling a constructor.

-

A constructor is similar to a method but is called implicitly by
the new operator to initialize an object’s instance variables when
the object is created.

-

In any class that does not explicitly declare a constructor, the
compiler provides a default constructor (which always has no
parameters).

-

When a class has only the default constructor, the class’s
instance variables are initialized to their default value.

METHODS
-

You can provide your own constructor to specify custom
initialization for objects of your class.

-

A constructor must have the same name as the class.

-

If you declare a constructor for a class, the compiler will
not create a default constructor that class.

public
class Account {
private double balance;
private String name;
public Account( String name, double balance ){
this.name = name;
this.balance = balance;
}
/* … rest of class … */
}

● to use the class and its methods
public static void main(String[] args){
Account myAccount = new Account("Sam", 1000);
Account yourAccount = new Account("Jane", 2000);
}

JAVA GARBAGE COLLECTION
-

More than one variable may refer to the same data.

-

Java will clear out old data that no variables are referencing
-

-

This is known as garbage collection

Garbage collection is the process through which Java will
eventually clear out old data that no variables are
referencing.

JAVADOC
-

Javadoc comments are delimited between /** and */.

-

Javadoc comments enable you to embed program documentation
directly in your programs.

-

Javadoc utility program reads Javadoc comments and uses them
to prepare program documentation in HTML web-page format.
/**
* This is a Javadoc comment!
*/

JAVADOC
-

Javadoc comments annotations:
-

@author: designates the author of the code, belongs in the
class comment

-

@param: designates the parameter to a method, belongs in all
method comments which require parameters

-

@return: designates the returned value of a method, belongs in
method comments which return values

JAVADOC
Jav

ine
til t
l
u
M
men
Com

/**
* The Account class represents a bank account.
* @author CS3443
*/
public class Account {
/* attributes here .. a multi-line comment starts with /* .. be careful! */
/**
* sets the account balance
* @param balance, the account balance (double)
*/
public void setBalance(double balance){
this.balance = balance;
}

doc

a

Jav

c
ado

}

/**
* returns the balance for the account
* @return double, the account balance
*/
public double getBalance(){
return balance;
}

JAVADOC

-

To generate Javadoc in Eclipse
1.

Project > Generate Javadoc

2.

Destination: workspace/your_project/doc

3.

Next

4.

Select all “referenced archives and projects”

5.

Finish > Yes To All

6.

Open index.html

Project > Generate Javadoc

Destination:workspace/your_project/doc
> Next

Select all
> Finish

Yes To All

Open index.html

CODE DEMO
-

Create a Java class
following the best
practices

-

Generate Javadocs

DO YOU HAVE ANY
QUESTIONS?

THANK
YOU!

@

hend.alkittawi@utsa.edu

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