**Post Overview:**
This post summarizes **Java Functional Programming**.

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## Table of Contents 
- [Functional Interfaces](#functional-interfaces)
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## Functional Interfaces  
1. **Callable&lt;V&gt;**

- Represent a function that **takes no arguments**, **returns a result** and **may throw an exception.**.
- Commonly used with **ExecutorService** or **FutureTask** to run computations in another thread and retrieve the result, or any object that needs to perform actions.
-  Its functional method is ***V call() throws Exception***. 

2. **Runnable**

- Represents a function that **takes no arguments** and **returns no result**.
- Used by **Thread**, **ExecutorService**, **UI framrworks (Swing, JavaFX)**, **FutureTask**, or any object that needs to perform actions.
-  Its functional method is **void run()**.

3. **Predicate&lt;T&gt;**

- Represents a function that **takes one argument** and **returns a boolean result**.
- Often used in filtering, matching, and test conditions.
- Its functional method is **boolean test(T t)**. 

4. **Function&lt;T,R&gt;**
- Represents a function that **takes one argument** and **returns a result**.
- Used anywhere you need to transform or map a value.
- Its functional method is **R apply(T t)**.

5. **Consumer&lt;T&gt;**
- Represents a function that **takes one argument** and **returns no result**.
- Mostly used for side-effects, i.e., actions performed on each element of a collection or stream, logging, printing, updating state, etc.
- Its functional method is **void accept(T t)**.

6. **Supplier&lt;T&gt;**
- Represents a function that **takes no arguments** and **returns a result**.
- Used when you want to generate or supply a value on demand.  
- Its functional method is **T get()**.