Features of Java

Platform independence, OOP, multithreading, security

Interview Relevant: Core features are frequently discussed in technical interviews
Last Updated: December 5, 2025 • 6 min read

Java has become one of the most popular programming languages in the world. Its features are carefully designed to offer developers a robust, versatile, and powerful environment.

Let's dive into the essential features that make Java a go-to choice for developers across various industries.

Object-Oriented Programming

At its core, Java is an object-oriented programming (OOP) language. This means it focuses on objects, which can encapsulate data and functionality.

OOP provides several benefits:

  • Encapsulation: This allows you to bundle data (attributes) and methods (functions) that operate on that data into a single unit. It helps in hiding the internal state of the object from the outside world.
  • Inheritance: This allows one class to inherit the properties and methods of another, fostering code reuse and establishing a natural hierarchy.
  • Polymorphism: This allows methods to do different things based on the object that it is acting upon, enhancing flexibility and integration.

Through these OOP principles, Java promotes modular, maintainable, and scalable code.

Platform Independence

One of Java's most celebrated features is its platform independence. This is achieved through the Java Virtual Machine (JVM).

When you write Java code, you compile it into bytecode, which is platform-independent. This means that the same bytecode can run on any machine that has a JVM.

Automatic Memory Management

Java uses automatic memory management, primarily through its Garbage Collector (GC). This means that you don't have to manually allocate and deallocate memory, which reduces the chances of memory leaks and other related issues.

For instance, when an object is no longer referenced, the garbage collector automatically reclaims that memory.

💡 Best Practice: While Java's garbage collector is very effective, it's still good practice to nullify references when you are done with an object, especially for large objects.

This feature simplifies memory management and allows developers to focus more on writing the logic of their programs rather than worrying about memory allocation.

Rich Standard Library

Java comes with a rich standard library (often referred to as the Java API) that provides built-in classes and methods for a wide range of functionalities. This includes:

  • Data Structures: Collections framework for lists, sets, maps, and more.
  • Networking: Classes for building networked applications.
  • File I/O: APIs for reading and writing files.
  • Concurrency: Tools for multi-threading and synchronization.

With such a robust library, you can accomplish a lot with minimal effort, speeding up development time and reducing the need to reinvent the wheel.

Multithreading

Java's built-in multithreading capabilities allow you to create applications that can perform multiple tasks simultaneously. This is crucial for modern applications that require responsiveness and efficiency.

⚠️ Warning: While multithreading offers powerful capabilities, it also introduces complexity, such as race conditions and deadlocks. Always ensure proper synchronization when multiple threads access shared resources.

Exception Handling

Java has a built-in exception handling mechanism that helps you manage runtime errors gracefully. This prevents your application from crashing and allows you to handle errors logically.

Java uses try, catch, and finally blocks to manage exceptions.

Next Chapter: Now that you understand the key features of Java, you are ready to explore the components that make Java run: the JDK, JRE, and JVM. In the next chapter, we will look at how these elements work together and why they are essential for developing Java applications.

Code Examples

Write your Java code in HelloWorld.java and compile it to demonstrate platform independence.

java
1public class HelloWorld {
2	public static void main(String[] args) {
3		System.out.println("Hello, World!");
4	}
5}

Compilation and execution process showing platform independence - the bytecode runs on any system with a JVM.

java
1# Compile the Java source file
2javac HelloWorld.java
3
4# This generates a HelloWorld.class file with platform-independent bytecode
5
6# You can run it on any machine with the JVM
7java HelloWorld

Once str is set to null, the String object can be collected by the Garbage Collector because there are no references to it.

java
1public class Example {
2    public static void main(String[] args) {
3        String str = new String("Hello");
4        str = null; // The object is now eligible for garbage collection
5    }
6}

When the division by zero occurs, the catch block handles the exception, allowing the program to continue running. The finally block executes regardless of whether an exception was thrown, making it useful for cleanup activities like closing files or releasing resources.

java
1public class ExceptionExample {
2    public static void main(String[] args) {
3        try {
4            int result = 10 / 0; // This will throw an ArithmeticException
5        } catch (ArithmeticException e) {
6            System.out.println("Cannot divide by zero: " + e.getMessage());
7        } finally {
8            System.out.println("This block always executes.");
9        }
10    }
11}

Use Cases

  • Object-Oriented Programming - Building modular, maintainable enterprise applications
  • Platform Independence - Write once, run anywhere capability for cross-platform deployment
  • Automatic Memory Management - Developing complex applications without manual memory handling
  • Rich Standard Library - Rapid development using built-in data structures, networking, and I/O
  • Multithreading - Creating responsive applications with concurrent task execution
  • Exception Handling - Building robust applications with graceful error recovery

Common Mistakes to Avoid

  • Not understanding the difference between checked and unchecked exceptions
  • Overusing inheritance instead of composition (violating "favor composition over inheritance")
  • Ignoring the performance implications of garbage collection in high-performance scenarios
  • Creating memory leaks by keeping references to objects that are no longer needed
  • Not synchronizing shared resources in multithreaded applications leading to race conditions
  • Catching generic Exception instead of specific exception types
  • Not using the finally block for cleanup operations like closing resources