What is Encapsulation in java ?
📍 Encapsulation is one of the fundamental principle of object oriented programming .
📍 Encapsulation allows to protect the data within a class from outside entities.
📍 Encapsulation helps to achieve hiding the internal information from outside entities.
📍 Data and methods (To access the data) are bundled together within a single unit .(class)
📍 In Java, encapsulation is typically achieved by:
Declaring the class members as private.
Providing public getter and setter methods to access and modify the private attributes.
Note :
Let's say we have 1 private variables in a class
Example - 1:
getter & setter for primitive type private members.
private String empnm;
// get method to access the data
public String GetName() {
return empnm;
}
// set the data
public void setName(String enm) {
this.empnm = enm;
} // call the method & pass the data as param
If we can notice the getter & setter for empnm , below points we can note:
1. getter method will return the variable which is private and it is non parameterized .
2. setter method is a parameterized method which we shall use to set the value for the private member while calling , so only it is parameterized method.
Example -2 :getter & Setter for the private array :
public int[] getarr() {
return arr;
}
// Setter method to modify the private array
public void setarr(int[] brr) {
// You can add validation or other logic if needed
this.arr = brr;
}
Best Programming Resources: https://topmate.io/coding/886839
All the best 👍👍
📍 Encapsulation is one of the fundamental principle of object oriented programming .
📍 Encapsulation allows to protect the data within a class from outside entities.
📍 Encapsulation helps to achieve hiding the internal information from outside entities.
📍 Data and methods (To access the data) are bundled together within a single unit .(class)
📍 In Java, encapsulation is typically achieved by:
Declaring the class members as private.
Providing public getter and setter methods to access and modify the private attributes.
Note :
Let's say we have 1 private variables in a class
Example - 1:
getter & setter for primitive type private members.
private String empnm;
// get method to access the data
public String GetName() {
return empnm;
}
// set the data
public void setName(String enm) {
this.empnm = enm;
} // call the method & pass the data as param
If we can notice the getter & setter for empnm , below points we can note:
1. getter method will return the variable which is private and it is non parameterized .
2. setter method is a parameterized method which we shall use to set the value for the private member while calling , so only it is parameterized method.
Example -2 :getter & Setter for the private array :
public int[] getarr() {
return arr;
}
// Setter method to modify the private array
public void setarr(int[] brr) {
// You can add validation or other logic if needed
this.arr = brr;
}
Best Programming Resources: https://topmate.io/coding/886839
All the best 👍👍
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Typical java interview questions sorted by experience
Junior
* Name some of the characteristics of OO programming languages
* What are the access modifiers you know? What does each one do?
* What is the difference between overriding and overloading a method in Java?
* What’s the difference between an Interface and an abstract class?
* Can an Interface extend another Interface?
* What does the static word mean in Java?
* Can a static method be overridden in Java?
* What is Polymorphism? What about Inheritance?
* Can a constructor be inherited?
* Do objects get passed by reference or value in Java? Elaborate on that.
* What’s the difference between using == and .equals on a string?
* What is the hashCode() and equals() used for?
* What does the interface Serializable do? What about Parcelable in Android?
* Why are Array and ArrayList different? When would you use each?
* What’s the difference between an Integer and int?
* What is a ThreadPool? Is it better than using several “simple” threads?
* What the difference between local, instance and class variables?
Mid
* What is reflection?
* What is dependency injection? Can you name a few libraries? (Have you used any?)
* What are strong, soft and weak references in Java?
* What does the keyword synchronized mean?
* Can you have “memory leaks” on Java?
* Do you need to set references to null on Java/Android?
* What does it means to say that a String is immutable?
* What are transient and volatile modifiers?
* What is the finalize() method?
* How does the try{} finally{} works?
* What is the difference between instantiation and initialisation of an object?
* When is a static block run?
* Why are Generics are used in Java?
* Can you mention the design patterns you know? Which of those do you normally use?
* Can you mention some types of testing you know?
Senior
* How does Integer.parseInt() works?
* Do you know what is the “double check locking” problem?
* Do you know the difference between StringBuffer and StringBuilder?
* How is a StringBuilder implemented to avoid the immutable string allocation problem?
* What does Class.forName method do?
* What is Autoboxing and Unboxing?
* What’s the difference between an Enumeration and an Iterator?
* What is the difference between fail-fast and fail safe in Java?
* What is PermGen in Java?
* What is a Java priority queue?
* *s performance influenced by using the same number in different types: Int, Double and Float?
* What is the Java Heap?
* What is daemon thread?
* Can a dead thread be restarted?
Source: medium.
Junior
* Name some of the characteristics of OO programming languages
* What are the access modifiers you know? What does each one do?
* What is the difference between overriding and overloading a method in Java?
* What’s the difference between an Interface and an abstract class?
* Can an Interface extend another Interface?
* What does the static word mean in Java?
* Can a static method be overridden in Java?
* What is Polymorphism? What about Inheritance?
* Can a constructor be inherited?
* Do objects get passed by reference or value in Java? Elaborate on that.
* What’s the difference between using == and .equals on a string?
* What is the hashCode() and equals() used for?
* What does the interface Serializable do? What about Parcelable in Android?
* Why are Array and ArrayList different? When would you use each?
* What’s the difference between an Integer and int?
* What is a ThreadPool? Is it better than using several “simple” threads?
* What the difference between local, instance and class variables?
Mid
* What is reflection?
* What is dependency injection? Can you name a few libraries? (Have you used any?)
* What are strong, soft and weak references in Java?
* What does the keyword synchronized mean?
* Can you have “memory leaks” on Java?
* Do you need to set references to null on Java/Android?
* What does it means to say that a String is immutable?
* What are transient and volatile modifiers?
* What is the finalize() method?
* How does the try{} finally{} works?
* What is the difference between instantiation and initialisation of an object?
* When is a static block run?
* Why are Generics are used in Java?
* Can you mention the design patterns you know? Which of those do you normally use?
* Can you mention some types of testing you know?
Senior
* How does Integer.parseInt() works?
* Do you know what is the “double check locking” problem?
* Do you know the difference between StringBuffer and StringBuilder?
* How is a StringBuilder implemented to avoid the immutable string allocation problem?
* What does Class.forName method do?
* What is Autoboxing and Unboxing?
* What’s the difference between an Enumeration and an Iterator?
* What is the difference between fail-fast and fail safe in Java?
* What is PermGen in Java?
* What is a Java priority queue?
* *s performance influenced by using the same number in different types: Int, Double and Float?
* What is the Java Heap?
* What is daemon thread?
* Can a dead thread be restarted?
Source: medium.
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Java for Everything: ☕
Java + Spring = Enterprise Applications
Java + Hibernate = Object-Relational Mapping
Java + Android = Mobile App Development
Java + Swing = Desktop GUI Applications
Java + JavaFX = Modern GUI Applications
Java + JUnit = Unit Testing
Java + Maven = Project Management
Java + Jenkins = Continuous Integration
Java + Apache Kafka = Stream Processing
Java + Apache Hadoop = Big Data Processing
Java + Microservices = Scalable Services
Best Programming Resources: https://topmate.io/coding/886839
All the best 👍👍
Java + Spring = Enterprise Applications
Java + Hibernate = Object-Relational Mapping
Java + Android = Mobile App Development
Java + Swing = Desktop GUI Applications
Java + JavaFX = Modern GUI Applications
Java + JUnit = Unit Testing
Java + Maven = Project Management
Java + Jenkins = Continuous Integration
Java + Apache Kafka = Stream Processing
Java + Apache Hadoop = Big Data Processing
Java + Microservices = Scalable Services
Best Programming Resources: https://topmate.io/coding/886839
All the best 👍👍
👍2
Learn for Full Stack Web Dev for Free ⚡
🔺HTML-> w3schools
🔺CSS -> freeCodeCamp
🔺Javascript -> @javascript_courses
🔺NodeJS -> freeCodeCamp
🔺ExpressJS -> MDN
🔺MongoDB -> MDB University
🔺REST APIs -> Postman
🔺Git -> learnGitBranching
🔺Deployment -> Firebase
🔺HTML-> w3schools
🔺CSS -> freeCodeCamp
🔺Javascript -> @javascript_courses
🔺NodeJS -> freeCodeCamp
🔺ExpressJS -> MDN
🔺MongoDB -> MDB University
🔺REST APIs -> Postman
🔺Git -> learnGitBranching
🔺Deployment -> Firebase
👍2
Java is a popular programming language that is widely used for developing various types of applications, including web applications, mobile apps, desktop applications, and enterprise systems. Here are some key concepts to understand the basics of Java:
1. Object-Oriented Programming (OOP): Java is an object-oriented programming language, which means it focuses on creating objects that contain both data and methods to operate on that data. Key principles of OOP in Java include encapsulation, inheritance, and polymorphism.
2. Classes and Objects: In Java, a class is a blueprint for creating objects. An object is an instance of a class that represents a real-world entity. Classes define the properties (attributes) and behaviors (methods) of objects.
3. Variables and Data Types: Java supports various data types, including primitive data types (e.g., int, double, boolean) and reference data types (e.g., String, arrays). Variables are used to store data values in memory.
4. Methods: Methods in Java are functions defined within a class to perform specific tasks. They encapsulate behavior and can accept parameters and return values.
5. Control Flow Statements: Java provides control flow statements such as if-else, switch-case, loops (for, while, do-while), and break/continue statements to control the flow of program execution.
6. Inheritance: Inheritance is a key feature of OOP that allows a class (subclass) to inherit properties and behaviors from another class (superclass). It promotes code reusability and establishes an "is-a" relationship between classes.
7. Polymorphism: Polymorphism allows objects of different classes to be treated as objects of a common superclass. It enables methods to be overridden in subclasses to provide different implementations.
8. Abstraction: Abstraction involves hiding the complex implementation details and showing only the essential features of an object. Abstract classes and interfaces are used to achieve abstraction in Java.
9. Encapsulation: Encapsulation is the process of bundling data (attributes) and methods that operate on that data within a class. It helps in data hiding and protects the internal state of an object.
10. Exception Handling: Java provides mechanisms for handling exceptions that occur during program execution. The try-catch-finally blocks are used to handle exceptions gracefully and prevent program crashes.
Understanding these basic concepts of Java will help you get started with programming in Java. Practice writing Java programs, exploring different features of the language, and building small projects to strengthen your Java skills.
1. Object-Oriented Programming (OOP): Java is an object-oriented programming language, which means it focuses on creating objects that contain both data and methods to operate on that data. Key principles of OOP in Java include encapsulation, inheritance, and polymorphism.
2. Classes and Objects: In Java, a class is a blueprint for creating objects. An object is an instance of a class that represents a real-world entity. Classes define the properties (attributes) and behaviors (methods) of objects.
3. Variables and Data Types: Java supports various data types, including primitive data types (e.g., int, double, boolean) and reference data types (e.g., String, arrays). Variables are used to store data values in memory.
4. Methods: Methods in Java are functions defined within a class to perform specific tasks. They encapsulate behavior and can accept parameters and return values.
5. Control Flow Statements: Java provides control flow statements such as if-else, switch-case, loops (for, while, do-while), and break/continue statements to control the flow of program execution.
6. Inheritance: Inheritance is a key feature of OOP that allows a class (subclass) to inherit properties and behaviors from another class (superclass). It promotes code reusability and establishes an "is-a" relationship between classes.
7. Polymorphism: Polymorphism allows objects of different classes to be treated as objects of a common superclass. It enables methods to be overridden in subclasses to provide different implementations.
8. Abstraction: Abstraction involves hiding the complex implementation details and showing only the essential features of an object. Abstract classes and interfaces are used to achieve abstraction in Java.
9. Encapsulation: Encapsulation is the process of bundling data (attributes) and methods that operate on that data within a class. It helps in data hiding and protects the internal state of an object.
10. Exception Handling: Java provides mechanisms for handling exceptions that occur during program execution. The try-catch-finally blocks are used to handle exceptions gracefully and prevent program crashes.
Understanding these basic concepts of Java will help you get started with programming in Java. Practice writing Java programs, exploring different features of the language, and building small projects to strengthen your Java skills.
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Why Learn Java?
1 - Beginner-Friendly :
Easy to learn and understand for coding newcomers.
2 - Versatile :
Used for web, mobile, desktop apps, and even games.
3 - Platform-Independent :
“Write once, run anywhere” with Java Virtual Machine (JVM).
4 - Highly Secure :
Perfect for banking and enterprise-level applications.
5 - Strong Job Market :
Java developers are always in demand worldwide.
6 - Powerful Community :
Tons of resources, libraries, and frameworks available.
7 - Scalable :
Ideal for building apps that grow with user demand.
Join our WhatsApp channel for the free resources: https://whatsapp.com/channel/0029VamdH5mHAdNMHMSBwg1s
1 - Beginner-Friendly :
Easy to learn and understand for coding newcomers.
2 - Versatile :
Used for web, mobile, desktop apps, and even games.
3 - Platform-Independent :
“Write once, run anywhere” with Java Virtual Machine (JVM).
4 - Highly Secure :
Perfect for banking and enterprise-level applications.
5 - Strong Job Market :
Java developers are always in demand worldwide.
6 - Powerful Community :
Tons of resources, libraries, and frameworks available.
7 - Scalable :
Ideal for building apps that grow with user demand.
Join our WhatsApp channel for the free resources: https://whatsapp.com/channel/0029VamdH5mHAdNMHMSBwg1s
👍5