Encapsulation provides benefits such as reducing complexity, ensuring structural changes remain local, and allowing for validation and data binding. It works by hiding implementation details and wrapping code and data together. Objects use private fields and public getters/setters for access. Access modifiers like private, protected, and public control visibility. Validation occurs in setters through exceptions. Mutable objects can be modified after creation while immutable objects cannot. The final keyword prevents inheritance, method overriding, or variable reassignment.
Super keyword is a reference variable that is used for refer parent class object. Super keyword is used in java at three level, at variable level, at method level and at constructor level.
Java abstract class & abstract methods,Abstract class in java
Abstract classes are classes that contain one or more abstract methods. An abstract method is a method that is declared, but contains no implementation. Abstract classes may not be instantiated, and require subclasses to provide implementations for the abstract methods.
Interface in java ,multiple inheritance in java, interface implementationHoneyChintal
multiple inheritance in java, interface implementation, abstraction,
multiple inheritance in java using interface, how to use interface,
how to use java, how to execute a java code
This ppt gives a general idea about the multithreading concepts in the java programming language. hope you find it useful
P.S :
sorry there is a correction in one of the slides
where i have entered implements thread
it is wrong it is actually implements Runnable
thank you!
Super keyword is a reference variable that is used for refer parent class object. Super keyword is used in java at three level, at variable level, at method level and at constructor level.
Java abstract class & abstract methods,Abstract class in java
Abstract classes are classes that contain one or more abstract methods. An abstract method is a method that is declared, but contains no implementation. Abstract classes may not be instantiated, and require subclasses to provide implementations for the abstract methods.
Interface in java ,multiple inheritance in java, interface implementationHoneyChintal
multiple inheritance in java, interface implementation, abstraction,
multiple inheritance in java using interface, how to use interface,
how to use java, how to execute a java code
This ppt gives a general idea about the multithreading concepts in the java programming language. hope you find it useful
P.S :
sorry there is a correction in one of the slides
where i have entered implements thread
it is wrong it is actually implements Runnable
thank you!
This keyword is a reference variable that refer the current object in java.
This keyword can be used for call current class constructor.
http://www.tutorial4us.com/java/java-this-keyword
This keyword is a reference variable that refer the current object in java.
This keyword can be used for call current class constructor.
http://www.tutorial4us.com/java/java-this-keyword
In this session you will learn:
Deep dive into coding OOP with Java… with practical examples.
How to create a class
How to create objects
How to create instance variables
How to create class variables
Constructors
For more information: https://www.mindsmapped.com/courses/software-development/become-a-java-developer-hands-on-training/
Simple class and object examples in java
classes
objects
fields
properties
variables
instance variables
local variables
class variables
methods
members of class
data members
UML representation of class
instance methods
static methods
create object
instantiate object
object qualifier
reference to object
allocate memory to object
class naming conventions
fields naming conventions
Hello. Im currently working on the last section to my assignment a.pdfirshadkumar3
Hello. I\'m currently working on the last section to my assignment and I\'m running into issues.
I\'ll post a screenshot of the directions provided to us, my 5 classes, and a screenshot of my
console output. Can you help me fix my code? I don\'t know where it\'s going wrong and I can\'t
figure it out. Please leave comments on what I did wrong so I can learn from it. Thank you so
much!
Here is the instructions from the pdf for reference on what I\'m trying to accomplish.
package campus;
public class Person {
private String id;
private String lastName;
private String firstName;
public Person(String id, String last, String first)
{
this.id = id;
this.lastName = last;
this.firstName = first;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getId() {
return id;
}
public String toString()
{
return id + \": \" + firstName + \" \" + lastName;
}
}
------
---Student.java---
package campus;
public class Student extends Person {
private String major;
private int level;
private Person obj;
public Student(String id, String last, String first, String focus, int level) {
super(id, last, first);// calling parent constructor
this.major = focus;
this.level = level;
obj = new Person(id, last, first);
}
public String getMajor() {
return major;
}
public void setMajor(String major) {
this.major = major;
}
public int getLevel() {
return level;
}
public void setLevel(int level) {
this.level = level;
}
@Override
public String toString() { // override toString() method
return \"id: \" + obj.getId() + \", Name: \" + obj.getFirstName() + \" \" + obj.getLastName()
+ \", major is \"
+ this.major + \" and their level is \" + this.level;
}
}
------
---Faculty.java---
package campus;
public class Faculty extends Person {
private String dept;
private String rank;
private Person obj;
public Faculty(String id, String last, String first, String focus, int level) {
super(id, last, first);// calling parent constructor
}
public String getDept() {
return dept;
}
public void setDept(String dept) {
this.dept = dept;
}
public String getRank() {
return rank;
}
public void setRank(int level) {
this.rank = rank;
}
@Override
public String toString() { // override toString() method
return \"id: \" + obj.getId() + \", Name: \" + obj.getFirstName() + \" \" + obj.getLastName()
+ \", deptartment is \"
+ this.dept + \" and their rank is \" + this.rank;
}
}
------
---Section.java---
package campus;
public class Section {
private String id;
private Faculty instructor;
private Student[] enrolled;
private int numofEnroll;
private int capacity;
private String location;
private String time;
private String semester;
public Section(String id, Faculty instructor, int capacity, String location, String time, String
semester) {
}
public Section(String id, int capacity) {
this.id = id;
this.capacity .
17. Java data structures trees representation and traversalIntro C# Book
In this chapter we will discuss tree data structures, like trees and graphs. The abilities of these data structures are really important for the modern programming. Each of this data structures is used for building a model of real life problems, which are efficiently solved using this model.
In this chapter we will discuss one recommended practice for efficiently solving computer programming problems and make a demonstration with appropriate examples. We will discuss the basic engineering principles of problem solving, why we should follow them when solving computer programming problems (the same principles can also be applied to find the solutions of many mathematical and scientific problems as well) and we will make an example of their use. We will describe the steps, in which we should go in order to solve some sample problems and show the mistakes that can occur when we do not follow these same steps. We will pay attention to some important steps from the methodology of problem solving, that we usually skip, e.g. the testing. We hope to be able to prove you, with proper examples, that the solving of computer programming problems has a "recipe" and it is very useful.
In this chapter we review the basic rules and recommendations for writing quality program code. We pay attention to naming the identifiers in the program (variables, methods, parameters, classes, etc.), formatting and code organization rules, good practices for composing methods, and principles for writing quality documentation.
Here we are going to learn why is a good practice to use interfaces and how they are different from abstraction classes. Further more we are going to see how which one of them to use.
19. Java data structures algorithms and complexityIntro C# Book
In this chapter we will compare the data structures we have learned so far by the performance (execution speed) of the basic operations (addition, search, deletion, etc.). We will give specific tips in what situations what data structures to use.
In this chapter we will understand how to define custom classes and their elements. We will learn to declare fields, constructors and properties for the classes. We will revise what a method is and we will broaden our knowledge about access modifiers and methods.
In this chapter we will explore strings. We are going to explain how they are implemented in Java and in what way we can process text content. Additionally, we will go through different methods for manipulating a text: we will learn how to compare strings, how to search for substrings, how to extract substrings upon previously settled parameters and last but not least how to split a string by separator chars. We will demonstrate how to correctly build strings with the StringBuilder class. We will provide a short but very useful information for the most commonly used regular expressions.
In this chapter we will discuss exceptions in the object-oriented programming and in Java in particular. We will learn how to handle exceptions using the try-catch construct, how to pass them to the calling methods and how to throw standard or our own exceptions using the throw construct.
Here we are going to take a look how to use for loop, foreach loop and while loop. Also we are going to learn how to use and invoke methods and how to define classes in Java programming language.
03 and 04 .Operators, Expressions, working with the console and conditional s...Intro C# Book
In this chapter we will get acquainted with the operators in Java and the actions they can perform on the different data types. We will explain the priorities of the operators and we will analyze the different types of operators, according to the count of the arguments they can take and the actions they can perform. In the second part we will examine the conversion of data types.
In this chapter we will get familiar with primitive types and variables in Java – what they are and how to work with them. First we will consider the data types – integer types, real types with floating-point, Boolean, character, string and object type. We will continue with the variables, with their characteristics, how to declare them, how they are assigned a value and what is variable initialization.
01. Introduction to programming with javaIntro C# Book
In this chapter we will take a look at the basic programming terminology and we will write our first Java program. We will familiarize ourselves with programming – what it means and its connection to computers and programming languages.
In this chapter we will discuss one recommended practice for efficiently solving computer programming problems and make a demonstration with appropriate examples. We will discuss the basic engineering principles of problem solving, why we should follow them when solving computer programming problems (the same principles can also be applied to find the solutions of many mathematical and scientific problems as well) and we will make an example of their use. We will describe the steps, in which we should go in order to solve some sample problems and show the mistakes that can occur when we do not follow these same steps. We will pay attention to some important steps from the methodology of problem solving, that we usually skip, e.g. the testing. We hope to be able to prove you, with proper examples, that the solving of computer programming problems has a "recipe" and it is very useful
1.Wireless Communication System_Wireless communication is a broad term that i...JeyaPerumal1
Wireless communication involves the transmission of information over a distance without the help of wires, cables or any other forms of electrical conductors.
Wireless communication is a broad term that incorporates all procedures and forms of connecting and communicating between two or more devices using a wireless signal through wireless communication technologies and devices.
Features of Wireless Communication
The evolution of wireless technology has brought many advancements with its effective features.
The transmitted distance can be anywhere between a few meters (for example, a television's remote control) and thousands of kilometers (for example, radio communication).
Wireless communication can be used for cellular telephony, wireless access to the internet, wireless home networking, and so on.
This 7-second Brain Wave Ritual Attracts Money To You.!nirahealhty
Discover the power of a simple 7-second brain wave ritual that can attract wealth and abundance into your life. By tapping into specific brain frequencies, this technique helps you manifest financial success effortlessly. Ready to transform your financial future? Try this powerful ritual and start attracting money today!
APNIC Foundation, presented by Ellisha Heppner at the PNG DNS Forum 2024APNIC
Ellisha Heppner, Grant Management Lead, presented an update on APNIC Foundation to the PNG DNS Forum held from 6 to 10 May, 2024 in Port Moresby, Papua New Guinea.
Multi-cluster Kubernetes Networking- Patterns, Projects and GuidelinesSanjeev Rampal
Talk presented at Kubernetes Community Day, New York, May 2024.
Technical summary of Multi-Cluster Kubernetes Networking architectures with focus on 4 key topics.
1) Key patterns for Multi-cluster architectures
2) Architectural comparison of several OSS/ CNCF projects to address these patterns
3) Evolution trends for the APIs of these projects
4) Some design recommendations & guidelines for adopting/ deploying these solutions.
# Internet Security: Safeguarding Your Digital World
In the contemporary digital age, the internet is a cornerstone of our daily lives. It connects us to vast amounts of information, provides platforms for communication, enables commerce, and offers endless entertainment. However, with these conveniences come significant security challenges. Internet security is essential to protect our digital identities, sensitive data, and overall online experience. This comprehensive guide explores the multifaceted world of internet security, providing insights into its importance, common threats, and effective strategies to safeguard your digital world.
## Understanding Internet Security
Internet security encompasses the measures and protocols used to protect information, devices, and networks from unauthorized access, attacks, and damage. It involves a wide range of practices designed to safeguard data confidentiality, integrity, and availability. Effective internet security is crucial for individuals, businesses, and governments alike, as cyber threats continue to evolve in complexity and scale.
### Key Components of Internet Security
1. **Confidentiality**: Ensuring that information is accessible only to those authorized to access it.
2. **Integrity**: Protecting information from being altered or tampered with by unauthorized parties.
3. **Availability**: Ensuring that authorized users have reliable access to information and resources when needed.
## Common Internet Security Threats
Cyber threats are numerous and constantly evolving. Understanding these threats is the first step in protecting against them. Some of the most common internet security threats include:
### Malware
Malware, or malicious software, is designed to harm, exploit, or otherwise compromise a device, network, or service. Common types of malware include:
- **Viruses**: Programs that attach themselves to legitimate software and replicate, spreading to other programs and files.
- **Worms**: Standalone malware that replicates itself to spread to other computers.
- **Trojan Horses**: Malicious software disguised as legitimate software.
- **Ransomware**: Malware that encrypts a user's files and demands a ransom for the decryption key.
- **Spyware**: Software that secretly monitors and collects user information.
### Phishing
Phishing is a social engineering attack that aims to steal sensitive information such as usernames, passwords, and credit card details. Attackers often masquerade as trusted entities in email or other communication channels, tricking victims into providing their information.
### Man-in-the-Middle (MitM) Attacks
MitM attacks occur when an attacker intercepts and potentially alters communication between two parties without their knowledge. This can lead to the unauthorized acquisition of sensitive information.
### Denial-of-Service (DoS) and Distributed Denial-of-Service (DDoS) Attacks
Bridging the Digital Gap Brad Spiegel Macon, GA Initiative.pptxBrad Spiegel Macon GA
Brad Spiegel Macon GA’s journey exemplifies the profound impact that one individual can have on their community. Through his unwavering dedication to digital inclusion, he’s not only bridging the gap in Macon but also setting an example for others to follow.
5. Process of wrapping code and data together
into a single unit
Flexibility and extensibility of the code
Reduces complexity
Structural changes remain local
Allows validation and data binding
Encapsulation
5
6. Objects fields must be private
Use getters and setters for data access
Encapsulation
6
class Person {
private int age;
}
class Person {
public int getAge()
public void setAge(int age)
}
7. Encapsulation – Example
Fields should be private
Accessors and Mutators should be public
7
Person
-name: string
-age: int
+Person(String name, int age)
+getName(): String
+setName(String name): void
+getAge(): int
+setAge(int age): void
- == private
+ == public
8. this is a reference to the current object
this can refer to current class instance
this can invoke current class method
Keyword this (1)
8
public Person(String name) {
this.name = name;
}
public String fullName() {
return this.getFirstName() + " " + this.getLastName();
}
9. this can invoke current class constructor
Keyword this (2)
9
public Person(String name) {
this.firstName = name;
}
public Person (String name, Integer age) {
this(name);
this.age = age;
}
11. Object hides data from the outside world
Classes and interfaces cannot be private
Data can be accessed only within the
declared class itself
Private Access Modifier
11
class Person {
private String name;
Person (String name) {
this.name = name;
}
}
12. Grants access to subclasses
protected modifier cannot be applied to
classes and interfaces
Prevents a nonrelated class from trying to use it
Protected Access Modifier
12
class Team {
protected String getName () {…}
protected void setName (String name) {…}
}
13. Do not explicitly declare an access modifier
Available to any other class in the same package
Default Access Modifier
13
class Team {
String getName() {…}
void setName(String name) {…}
}
Team real = new Team("Real");
real.setName("Real Madrid");
System.out.println(real.getName());
// Real Madrid
14. Grants access to any class belonging to
the Java Universe
Import a package if you need to use a class
The main() method of an application
must be public
Public Access Modifier
14
public class Team {
public String getName() {…}
public void setName(String name) {…}
}
15. Create a class Person
Problem: Sort by Name and Age
15
Person
-firstName: String
-lastName: String
-age: int
+getFirstName(): String
+getLastName(): String
+getAge(): int
+toString(): String
Check your solution here :https://judge.softuni.bg/Contests/1535/Encapsulation-Lab
16. Solution: Sort by Name and Age
16
public class Person {
private String firstName;
private String lastName; private int age;
// TODO: Implement Constructor
public String getFirstName() { /* TODO */ }
public String getLastName() { /* TODO */ }
public int getAge() { return age; }
@Override
public String toString() { /* TODO */ }
}
17. Implement Salary
Add:
getter for salary
increaseSalary by percentage
Persons younger than 30 get
only half of the increase
Problem: Salary Increase
17
Person
-firstName: String
-lastName: String
-age: int
-salary: double
+getFirstName(): String
+getLastName() : String
+getAge() : int
+getSalary(): double
+setSalary(double): void
+increaseSalary(double): void
+toString(): String
18. Expand Person from previous task
Solution: Salary Increase (1)
18
public class Person {
private double salary;
// Edit Constructor
public double getSalary() {
return this.salary;
}
public void setSalary(double salary) {
this.salary = salary;
}
// Next Slide…
// TODO: Edit toString() method
}
Check your solution here :https://judge.softuni.bg/Contests/1535/Encapsulation-Lab
19. Expand Person from previous task
Solution: Salary Increase (2)
19
public void increaseSalary(double percentage) {
if (this.getAge() < 30) {
this.setSalary(this.getSalary() +
(this.getSalary() * percentage / 200));
} else {
this.setSalary(this.getSalary() +
(this.getSalary() * percentage / 100));
}
}
Check your solution here :https://judge.softuni.bg/Contests/1535/Encapsulation-Lab
21. Data validation happens in setters
Printing with System.out couples your class
Client can handle class exceptions
Validation (1)
21
private void setSalary(double salary) {
if (salary < 460) {
throw new IllegalArgumentException("Message");
}
this.salary = salary;
}
It is better to throw exceptions,
rather than printing to the Console
22. Constructors use private setters with validation logic
Guarantees valid state of object in its creation
Guarantees valid state for public setters
Validation (2)
22
public Person(String firstName, String lastName,
int age, double salary) {
setFirstName(firstName);
setLastName(lastName);
setAge(age);
setSalary(salary);
}
Validation happens
inside the setter
23. Expand Person with
validation for every field
Names should be
at least 3 symbols
Age cannot be zero or negative
Salary cannot be less than 460
Problem: Validation Data
23
Person
-firstName : String
-lastName : String
-age : int
-salary : double
+Person()
+setFirstName(String fName)
+setLastName(String lName)
+setAge(int age)
+setSalary(double salary)
Check your solution here :https://judge.softuni.bg/Contests/1535/Encapsulation-Lab
24. Solution: Validation Data
24
// TODO: Add validation for firstName
// TODO: Add validation for lastName
public void setAge(int age) {
if (age < 1) {
throw new IllegalArgumentException(
"Age cannot be zero or negative integer");
}
this.age = age;
}
// TODO: Add validation for salary
Check your solution here :https://judge.softuni.bg/Contests/1535/Encapsulation-Lab
26. Mutable vs Immutable Objects
Mutable Objects
The contents of that
instance can be altered
Immutable Objects
The contents of the
instance can't be altered
26
old String
old String
Point myPoint = new Point(0, 0);
myPoint.setLocation(1.0, 0.0);
System.out.println(myPoint);
java.awt.Point[1.0, 0.0]
String str = new String("old String");
System.out.println(str);
str.replaceAll("old", "new");
System.out.println(str);
27. private mutable fields are not fully encapsulated
In this case getter is like setter too
Mutable Fields
27
class Team {
private String name;
private List<Person> players;
public List<Person> getPlayers() {
return this.players;
}
}
28. Mutable Fields - Example
28
Team team = new Team();
Person person = new Person("David", "Adams", 22);
team.getPlayers().add(person);
System.out.println(team.getPlayers().size()); // 1
team.getPlayers().clear();
System.out.println(team.getPlayers().size()); // 0
29. For securing our collection we can return
Collections.unmodifiableList()
Imutable Fields
29
class Team {
private List<Person> players;
public void addPlayer(Person person) {
this.players.add(person);
}
public List<Person> getPlayers() {
return Collections.unmodifiableList(players);
}
}
Returns a safe collections
Add new methods for
functionality over list
30. Expand your project with class Team
Team have two squads
first team and reserve team
Read persons from console and
add them to team
If they are younger than 40,
they go to first squad
Print both squad sizes
Problem: First and Reserve Team
30
Team
-name: String
-firstTeam: List<Person>
-reserveTeam: List<Person>
+Team(String name)
+getName()
-setName(String name)
+getFirstTeam()
+getReserveTeam()
+addPlayer(Person person)
Check your solution here :https://judge.softuni.bg/Contests/1535/Encapsulation-Lab
31. Solution: First and Reserve Team
31
private List<Person> firstTeam;
private List<Person> reserveTeam;
public void addPlayer(Person person) {
if (person.getAge() < 40)
this.firstTeam.add(person);
else
this.reserveTeam.add(person);
}
public List<Person> getFirstTeam() {
return Collections.unmodifiableList(firstTeam);
}
// TODO: add getter for reserve team
Check your solution here :https://judge.softuni.bg/Contests/1535/Encapsulation-Lab
33. final class can't be extended
final method can't be overridden
Keyword final
33
public class Animal {}
public final class Mammal extends Animal {}
public class Cat extends Mammal {}
public final void move(Point point) {}
public class Mammal extends Animal {
@Override
public void move() {}
}
34. final variable value can't be changed once it is set
Keyword final
34
private final String name;
private final List<Person> firstTeam;
public Team (String name) {
this.name = name;
this.firstTeam = new ArrayList<Person> ();
}
public void doSomething(Person person) {
this.name = "";
this.firstTeam = new ArrayList<>();
this.firstTeam.add(person);
}
Compile time error
35. …
…
…
Summary
35
Encapsulation:
Hides implementation
Reduces complexity
Ensures that structural changes
remain local
Mutable and Immutable objects
Keyword final
39. Software University – High-Quality Education and
Employment Opportunities
softuni.bg
Software University Foundation
http://softuni.foundation/
Software University @ Facebook
facebook.com/SoftwareUniversity
Software University Forums
forum.softuni.bg
Trainings @ Software University (SoftUni)
40. This course (slides, examples, demos, videos, homework, etc.)
is licensed under the "Creative Commons Attribution-
NonCommercial-ShareAlike 4.0 International" license
License
40
Editor's Notes
Encapsulation hides the implementation details
Class announces only a few operations (methods) available for its clients – its public interface
All data members (fields) of a class should be hidden
Accessed via properties (read-only and read-write)
No interface members should be hidden
Encapsulation == hide (encapsulate) data behind constructors and properties
Encapsulation hides the implementation details
Class announces only a few operations (methods) available for its clients – its public interface
All data members (fields) of a class should be hidden
Accessed via properties (read-only and read-write)
No interface members should be hidden
Encapsulation == hide (encapsulate) data behind constructors and properties
Fields are private
Constructors and accessors are defined (getters and setters)
Constructors are declared public
Constructors perform checks to keep the object state valid
Interface methods are always public
Not explicitly declared with public
Non-interface methods are declared private / protected
Constructors are declared public
Constructors perform checks to keep the object state valid
Interface methods are always public
Not explicitly declared with public
Non-interface methods are declared private / protected
Access Level "public"
When we use the modifier public in front of some element, we are telling the compiler, that this element can be accessed from every class, no matter from the current project (assembly), from the current package. The access level public defines the miss of restrictions regarding the visibility. This access level is the least restricted access level in Java.
Access Level "private"
The access level private is the one, which defines the most restrictive level of visibility of the class and its elements. The modifier private is used to indicate, that the element, to which is issued, cannot be accessed from any other class (except the class, in which it is defined), even if this class exists in the same package.
Access Level “protected"
The access level private is the one, which defines the most restrictive level of visibility of the class and its elements. The modifier private is used to indicate, that the element, to which is issued, cannot be accessed from any other class (except the class, in which it is defined), even if this class exists in the same namespace.
Access Level “default"
This is the default access level, i.e. it is used when there is no access level modifier in front of the respective element of a class. Members can be accessed only from the same package.
Access Level "public"
When we use the modifier public in front of some element, we are telling the compiler, that this element can be accessed from every class, no matter from the current project (assembly), from the current package. The access level public defines the miss of restrictions regarding the visibility. This access level is the least restricted access level in Java.
Access Level "private"
The access level private is the one, which defines the most restrictive level of visibility of the class and its elements. The modifier private is used to indicate, that the element, to which is issued, cannot be accessed from any other class (except the class, in which it is defined), even if this class exists in the same package.
Access Level “protected"
The access level private is the one, which defines the most restrictive level of visibility of the class and its elements. The modifier private is used to indicate, that the element, to which is issued, cannot be accessed from any other class (except the class, in which it is defined), even if this class exists in the same namespace.
Access Level “default"
This is the default access level, i.e. it is used when there is no access level modifier in front of the respective element of a class. Members can be accessed only from the same package.
Access Level "public"
When we use the modifier public in front of some element, we are telling the compiler, that this element can be accessed from every class, no matter from the current project (assembly), from the current package. The access level public defines the miss of restrictions regarding the visibility. This access level is the least restricted access level in Java.
Access Level "private"
The access level private is the one, which defines the most restrictive level of visibility of the class and its elements. The modifier private is used to indicate, that the element, to which is issued, cannot be accessed from any other class (except the class, in which it is defined), even if this class exists in the same package.
Access Level “protected"
The access level private is the one, which defines the most restrictive level of visibility of the class and its elements. The modifier private is used to indicate, that the element, to which is issued, cannot be accessed from any other class (except the class, in which it is defined), even if this class exists in the same namespace.
Access Level “default"
This is the default access level, i.e. it is used when there is no access level modifier in front of the respective element of a class. Members can be accessed only from the same package.
Access Level "public"
When we use the modifier public in front of some element, we are telling the compiler, that this element can be accessed from every class, no matter from the current project (assembly), from the current package. The access level public defines the miss of restrictions regarding the visibility. This access level is the least restricted access level in Java.
Access Level "private"
The access level private is the one, which defines the most restrictive level of visibility of the class and its elements. The modifier private is used to indicate, that the element, to which is issued, cannot be accessed from any other class (except the class, in which it is defined), even if this class exists in the same package.
Access Level “protected"
The access level private is the one, which defines the most restrictive level of visibility of the class and its elements. The modifier private is used to indicate, that the element, to which is issued, cannot be accessed from any other class (except the class, in which it is defined), even if this class exists in the same namespace.
Access Level “default"
This is the default access level, i.e. it is used when there is no access level modifier in front of the respective element of a class. Members can be accessed only from the same package.
Constructors are declared public
Constructors perform checks to keep the object state valid
Interface methods are always public
Not explicitly declared with public
Non-interface methods are declared private / protected
Constructors are declared public
Constructors perform checks to keep the object state valid
Interface methods are always public
Not explicitly declared with public
Non-interface methods are declared private / protected
Fields are always declared private
Accessed through getters and setters in read-only or read-write mode
Setters perform checks to fight invalid data
Fields are always declared private
Accessed through getters and setters in read-only or read-write mode
Setters perform checks to fight invalid data
Fields are always declared private
Accessed through getters and setters in read-only or read-write mode
Setters perform checks to fight invalid data
Constructors are declared public
Constructors perform checks to keep the object state valid
Interface methods are always public
Not explicitly declared with public
Non-interface methods are declared private / protected