JAVA project ideas
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https://www.linkedin.com/posts/webdevcoursefree_java-developer-in-2024-stage-1-java-activity-7245059540101013505-oZSQ

Java in one notes.pdf

240 Java Interview Questions😎 #resources

Java interview questions along with brief answers

1. What is the difference between == and .equals() in Java?
- == compares object references, while .equals() compares the content of objects.

2. Explain the difference between ArrayList and LinkedList.
- ArrayList uses a dynamic array to store elements, providing fast random access. LinkedList uses a doubly-linked list, offering efficient insertion and deletion.

3. What is the significance of the static keyword in Java?
- The static keyword is used to create variables and methods that belong to the class rather than instances of the class. These can be accessed without creating an object.

4. What is the difference between an abstract class and an interface?
- An abstract class can have both abstract (unimplemented) and concrete (implemented) methods, while an interface can only have abstract methods. A class can implement multiple interfaces, but it can extend only one abstract class.

5. What is the purpose of the finally block in exception handling?
- The finally block is used to ensure that a specific block of code is always executed, regardless of whether an exception is thrown or not.

6. Explain the concept of multithreading in Java.
- Multithreading is the concurrent execution of two or more threads. Threads allow programs to run tasks in parallel, improving performance. In Java, you can create threads by extending the Thread class or implementing the Runnable interface.

7. What is the NullPointerException and how can it be avoided?
- NullPointerException occurs when you try to access a method or field of an object that is null. To avoid it, ensure that objects are properly initialized before accessing their members.

8. How does garbage collection work in Java?
- Garbage collection is the process of automatically reclaiming memory occupied by unreferenced objects. Java uses a garbage collector to identify and delete objects that are no longer reachable.

9. Explain the final keyword in Java.
- The final keyword can be applied to variables, methods, and classes. When applied to a variable, it means the variable's value cannot be changed. When applied to a method, it prevents method overriding. When applied to a class, it prevents the class from being subclassed.

10. What is the Java Virtual Machine (JVM)?
- JVM is a virtual machine that executes Java bytecode. It abstracts the hardware and operating system details, allowing Java programs to run on any device with a compatible JVM.

These questions cover a range of Java concepts commonly discussed in interviews. Be prepared to elaborate on your answers and provide examples if requested during an interview.

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.

Java Developer Interview ❤
It'll gonna be super helpful for YOU

𝗧𝗼𝗽𝗶𝗰 𝟭: 𝗣𝗿𝗼𝗷𝗲𝗰𝘁 𝗳𝗹𝗼𝘄 𝗮𝗻𝗱 𝗮𝗿𝗰𝗵𝗶𝘁𝗲𝗰𝘁𝘂𝗿𝗲
- Please tell me about your project and its architecture, Challenges faced?
- What was your role in the project? Tech Stack of project? why this stack?
- Problem you solved during the project? How collaboration within the team?
- What lessons did you learn from working on this project?
- If you could go back, what would you do differently in this project?

𝗧𝗼𝗽𝗶𝗰 𝟮: 𝗖𝗼𝗿𝗲 𝗝𝗮𝘃𝗮
- String Concepts/Hashcode- Equal Methods
- Immutability
- OOPS concepts
- Serialization
- Collection Framework
- Exception Handling
- Multithreading
- Java Memory Model
- Garbage collection

Tech Community
👉 t.me/Java_Programming_Notes

𝗧𝗼𝗽𝗶𝗰 𝟯: 𝗝𝗮𝘃𝗮-𝟴/𝗝𝗮𝘃𝗮-𝟭𝟭/𝗝𝗮𝘃𝗮𝟭𝟳
- Java 8 features
- Default/Static methods
- Lambda expression
- Functional interfaces
- Optional API
- Stream API
- Pattern matching
- Text block
- Modules

𝗧𝗼𝗽𝗶𝗰 𝟰: 𝗦𝗽𝗿𝗶𝗻𝗴 𝗙𝗿𝗮𝗺𝗲𝘄𝗼𝗿𝗸, 𝗦𝗽𝗿𝗶𝗻𝗴-𝗕𝗼𝗼𝘁, 𝗠𝗶𝗰𝗿𝗼𝘀𝗲𝗿𝘃𝗶𝗰𝗲, 𝗮𝗻𝗱 𝗥𝗲𝘀𝘁 𝗔𝗣𝗜
- Dependency Injection/IOC, Spring MVC
- Configuration, Annotations, CRUD
- Bean, Scopes, Profiles, Bean lifecycle
- App context/Bean context
- AOP, Exception Handler, Control Advice
- Security (JWT, Oauth)
- Actuators
- WebFlux and Mono Framework
- HTTP methods
- JPA
- Microservice concepts
- Spring Cloud

𝗧𝗼𝗽𝗶𝗰 𝟱: 𝗛𝗶𝗯𝗲𝗿𝗻𝗮𝘁𝗲/𝗦𝗽𝗿𝗶𝗻𝗴-𝗱𝗮𝘁𝗮 𝗝𝗽𝗮/𝗗𝗮𝘁𝗮𝗯𝗮𝘀𝗲 (𝗦𝗤𝗟 𝗼𝗿 𝗡𝗼𝗦𝗤𝗟)
- JPA Repositories
- Relationship with Entities
- SQL queries on Employee department
- Queries, Highest Nth salary queries
- Relational and No-Relational DB concepts
- CRUD operations in DB
- Joins, indexing, procs, function

𝗧𝗼𝗽𝗶𝗰 𝟲: 𝗖𝗼𝗱𝗶𝗻𝗴
- DSA Related Questions
- Sorting and searching using Java API.
- Stream API coding Questions

Tech Jobs and Internships
t.me/getjobss

𝗧𝗼𝗽𝗶𝗰 𝟳: 𝗗𝗲𝘃𝗼𝗽𝘀 𝗾𝘂𝗲𝘀𝘁𝗶𝗼𝗻𝘀 𝗼𝗻 𝗱𝗲𝗽𝗹𝗼𝘆𝗺𝗲𝗻𝘁 𝗧𝗼𝗼𝗹𝘀
- These types of topics are mostly asked by managers or leads who are heavily working on it, That's why they may grill you on DevOps/deployment-related tools, You should have an understanding of common tools like Jenkins, Kubernetes, Kafka, Cloud, and all.

𝗧𝗼𝗽𝗶𝗰𝘀 𝟴: 𝗕𝗲𝘀𝘁 𝗽𝗿𝗮𝗰𝘁𝗶𝗰𝗲
- The interviewer always wanted to ask about some design patterns, it may be Normal design patterns like singleton, factory, or observer patterns to know that you can use these in coding.

PDFs and Notes 📝
t.me/Java_Programming_Notes

Best Programming Resources: https://topmate.io/coding/886839

All the best 👍👍