🚀 Java 8 – Complete Guide to Core Features & Stream API Foundations

Welcome to the Java 8 Repository 👋
This repository is a comprehensive learning project that covers all major Java 8 features, with special emphasis on the functional programming concepts that are required to understand and use the Stream API effectively.

Java 8 was a game-changing release that introduced functional-style programming, new APIs, and modern coding practices that are still foundational in today’s Java ecosystem.

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🎯 Purpose of This Repository

The purpose of this repository is to:

• Learn all core Java 8 features with practical examples
• Understand functional interfaces that power the Stream API
• Practice lambda expressions and method references
• Master Stream API concepts with strong prerequisites
• Write clean, modern, and maintainable Java code
• Prepare for interviews and real-world Java development

Whether you are a beginner or a seasoned developer who want to explore Java 8, this repository will be a solid resource.

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This repository intentionally includes both:

1. Stream API prerequisites
2. Other essential Java 8 features

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✨ Java 8 Features Covered

1. Lambda Expressions : Write concise and readable code using functional-style syntax.

2. Functional Interfaces:
   Interfaces with a single abstract method that work seamlessly with lambda expressions.

3. Stream API
   Perform functional operations on collections using filter, map, forEach, reduce, and more.

4. Default and Static Methods in Interfaces
   Add behavior directly inside interfaces while maintaining backward compatibility.

5. Optional Class
   Handle null values safely and reduce the risk of NullPointerException.

6. Date and Time API
   Use modern, immutable, and thread-safe classes for date and time handling.

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🧠 Functional Interfaces Covered (Required for Stream API)

The repository includes dedicated demo classes for the functional interfaces that Streams internally depend on:

• Predicate:
  Used in Stream filtering operations.

• Consumer:
  Used in forEach and terminal operations.

• Supplier: Used for lazy data generation.

• Function:
  Used in map and transformation operations.

• UnaryOperator:
  Specialized Function where input and output types are the same.

• BinaryOperator:
  Used in reduce and aggregation operations.

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🧠 Bi-Functional Interfaces Covered

Advanced functional interfaces that work with two inputs and are commonly used with streams and maps:

• BiPredicate
• BiConsumer
• BiFunction

These are especially useful when working with Map streams and complex transformations.

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🔗 Combined Functional Programming Concepts

The repository also demonstrates how multiple functional interfaces work together to form pipelines similar to real Stream API usage, helping bridge the gap between theory and practical Stream processing.

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📌 Who Is This For?

• Students learning Java
• Developers upgrading from older Java versions
• Interview candidates
• Anyone who wants strong Java fundamentals with modern practices

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▶️ How to Use This Repository

1. Clone the repository

   git clone https://github.com/vivekjutture/Java-8.git

2. Open the project in any Java IDE
   IntelliJ IDEA / Eclipse / VS Code

3. Run each demo class individually

4. Observe how functional interfaces, lambdas, and streams interact

5. Use this knowledge to confidently work with Stream API

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🌟 Why This Repository Matters

Many developers try to learn Stream API directly and struggle.
This repository solves that problem by teaching:

• What Streams are built on
• Why functional interfaces matter
• How lambdas, functions, and predicates connect
• How Java 8 features work together as a whole

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🤝 Contribution Guidelines

Contributions are welcome and encouraged.

• You may add missing Java 8 features
• You may optimize existing code
• You may improve readability, structure, or performance of examples
• You may enhance documentation or add new demonstrations

The goal is to keep this repository evolving as a high-quality Java 8 learning resource.

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📜 License

This project under the MIT License, allowing free use, modification, and distribution.

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🙌 Final Note

This repository is designed as a complete Java 8 learning reference, not just isolated examples.
Mastering these concepts will make Streams, modern Java frameworks, and enterprise codebases much easier to understand.

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Happy Coding ☕🔥