ValueLabs Python Developer Interview Questions and Answers

Autoboxing is the automatic conversion of primitive data types to their corresponding object wrapper classes.

• Autoboxing is useful when working with collections that require objects instead of primitives.

• Example: int i = 5; Integer j = i; //autoboxing

• Unboxing is the opposite of autoboxing, where an object of a wrapper class is converted back to its corresponding primitive type.

• Example: Integer j = 5; int i = j; //unboxi

Typecasting up and down refers to converting a variable of one data type to another data type of higher or lower precision.

• Typecasting up involves converting a variable of lower precision to a variable of higher precision, such as converting an int to a double.

• Typecasting down involves converting a variable of higher precision to a variable of lower precision, such as converting a double to an int.

• Typecasting can resul...read more

To iterate a map in Java, use a for-each loop or an iterator.

• Use the entrySet() method to get a set of key-value pairs

• For-each loop: for(Map.Entry entry : map.entrySet())

• Iterator: Iterator> iterator = map.entrySet().iterator();

• Use hasNext() and next() methods to iterate through the map

Types of synchronization in Java

• Synchronized methods

• Synchronized statements

• ReentrantLock

• Semaphore

• CountDownLatch

Access modifiers in method overriding

• Access modifiers in the overriding method cannot be more restrictive than the overridden method

• The access modifier can be less restrictive or the same as the overridden method

• Private methods cannot be overridden

• Examples: public method can be overridden by public or protected method, but not by private method

The question is asking about the candidate's knowledge in Core Java, Spring, Hibernate, Spring Boot, SQL, and AngularJS.

• Core Java is the foundation of Java programming language.

• Spring is a popular framework for building Java applications.

• Hibernate is an ORM tool used for mapping Java objects to database tables.

• Spring Boot is a framework for building microservices.

• SQL is a language used for managing relational databases...read more

To connect 2 DBs from a Spring Boot application, configure multiple data sources and use JdbcTemplate or EntityManager for each DB.

• Configure multiple data sources in the application.properties file

• Create separate configuration classes for each data source

• Use JdbcTemplate or EntityManager to interact with each DB

• Specify the appropriate data source in the repository or service classes

Abstract method implementation is mandatory while default method is optional.

• Abstract method has no implementation in the abstract class and must be implemented by the subclass.

• Default method has a default implementation in the interface and can be overridden by the implementing class.

• Abstract method is used to enforce a contract while default method is used to provide a default behavior.

• Example: abstract method - publ...read more

Java is a high-level, object-oriented programming language used to develop applications for various platforms.

• Java is platform-independent and can run on any platform with a JVM.

• It is used for developing web, mobile, desktop, and enterprise applications.

• Java has a vast library of pre-built classes and APIs.

• It supports multithreading, exception handling, and garbage collection.

• Java is widely used in the industry for its...read more

Java is a popular, versatile, and reliable programming language used for developing a wide range of applications.

• Java is platform-independent, making it easy to write code once and run it on multiple platforms.

• It has a vast library of pre-built classes and APIs, making development faster and easier.

• Java is highly secure and provides built-in features for encryption and authentication.

• It is widely used in enterprise app...read more

Java is a high-level programming language known for its platform independence and object-oriented approach.

• Java is widely used for developing desktop, web, and mobile applications.

• It is known for its write once, run anywhere (WORA) capability.

• Java uses a virtual machine (JVM) to execute code, providing portability across different operating systems.

• It supports multithreading, exception handling, and dynamic memory allo...read more

Inheritance is a mechanism in object-oriented programming where a new class is created from an existing class.

• Allows for code reuse and promotes code organization

• The new class (subclass) inherits properties and methods from the existing class (superclass)

• Subclass can add new properties and methods or override existing ones

• Example: A Car class can inherit properties and methods from a Vehicle class