TCS iON Java Developer Interview Questions and Answers

OOP (Object-Oriented Programming) is a programming paradigm based on objects and classes to structure software design.

• Encapsulation: Bundling data and methods that operate on the data within one unit (e.g., a class).

• Inheritance: Mechanism where a new class derives properties and behavior from an existing class (e.g., a 'Dog' class inheriting from an 'Animal' class).

• Polymorphism: Ability to present the same interfa...read more

Stream API is a set of classes in Java that allow processing collections of objects in a functional style. Lambda expressions are used to write concise code for functional interfaces.

• Stream API provides a way to perform operations on collections like filter, map, reduce, etc.

• Lambda expressions are used to define anonymous functions in a concise way.

• Example: List<String> names = Arrays.asList("Alice", "Bob", ...read more

Optional class is used to handle null values in Java, preventing NullPointerExceptions.

• Optional class was introduced in Java 8 to provide a more elegant way of handling null values.

• It encourages developers to explicitly handle the presence or absence of a value, rather than relying on null checks.

• Optional class has methods like isPresent(), get(), orElse(), etc. to work with optional values.

• Using Optional class ca...read more

Encapsulation is the concept of bundling data and methods that operate on the data into a single unit.

• Encapsulation helps in hiding the internal state of an object and restricting access to it.

• It allows for better control over the data by preventing external code from directly modifying it.

• Example: A class 'Car' with private variables like 'model', 'year', and public methods like 'getYear()' and 'setModel()'.

Just-in-time (JIT) is a feature in Java that compiles bytecode into native machine code at runtime.

• JIT improves the performance of Java programs by reducing the time needed for compilation.

• JIT is enabled by default in most Java virtual machines.

• JIT can be disabled using the -Xint option.

• JIT can also be configured using various options such as -XX:CompileThreshold and -XX:MaxInlineLevel.

JIT stands for Just-In-Time compiler. It is a part of the Java Virtual Machine (JVM) that compiles bytecode into machine code at runtime.

• JIT is responsible for improving the performance of Java applications by compiling frequently executed code into native machine code.

• It analyzes the code at runtime and identifies the hotspots, i.e., the code that is executed frequently.

• JIT compiles the hotspots into machine code...read more