Advanced Java Programming: Streams, Lambda Expressions, JDBC, Networking, and Modern Java DevelopmentNew

Advanced Java Programming Guide

This tutorial is designed for learners who already understand Java basics and intermediate concepts such as OOP, collections, exception handling, and multithreading.

In this guide, we explore advanced Java topics that are commonly used in real-world software development. These include functional programming, database connectivity, networking, build tools, and modern Java frameworks.

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1. Lambda Expressions

Lambda expressions allow you to write shorter and cleaner code when working with functional interfaces.

Before Lambda Expressions:

Runnable r = new Runnable() {
    public void run() {
        System.out.println("Thread running");
    }
};

Using Lambda Expression:

Runnable r = () -> {
    System.out.println("Thread running");
};

This syntax makes code easier to read and write.

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2. Streams API

The Streams API helps process collections of data in a functional style.

Example filtering a list:

import java.util.Arrays;
import java.util.List;

List<Integer> numbers = Arrays.asList(1,2,3,4,5,6);

numbers.stream()
       .filter(n -> n % 2 == 0)
       .forEach(System.out::println);

This code prints only the even numbers from the list.

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3. Functional Interfaces

A functional interface contains exactly one abstract method.

@FunctionalInterface
interface Greeting {

    void sayHello();

}

Using Lambda:

Greeting g = () -> System.out.println("Hello Java");

g.sayHello();

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4. Annotations

Annotations provide metadata about the program.

Example built-in annotations:

• @Override
• @Deprecated
• @SuppressWarnings

@Override
public String toString() {
    return "Custom object";
}

Annotations are widely used in frameworks like Spring.

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5. Reflection API

The Reflection API allows Java programs to inspect and manipulate classes at runtime.

Class<?> obj = Class.forName("java.lang.String");

System.out.println(obj.getName());

This retrieves information about the String class during runtime.

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6. JDBC (Java Database Connectivity)

JDBC allows Java applications to connect to databases.

Connecting to a Database

import java.sql.Connection;
import java.sql.DriverManager;

Connection conn = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/mydb",
"root",
"password"
);

Executing Queries

import java.sql.Statement;

Statement stmt = conn.createStatement();

stmt.executeUpdate(
"INSERT INTO users(name) VALUES('John')"
);

Prepared Statements

Prepared statements help prevent SQL injection.

import java.sql.PreparedStatement;

PreparedStatement ps = conn.prepareStatement(
"INSERT INTO users(name) VALUES(?)"
);

ps.setString(1, "Alice");
ps.executeUpdate();

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7. Java Networking

Java supports network programming through sockets.

Server Example

import java.net.ServerSocket;
import java.net.Socket;

ServerSocket server = new ServerSocket(5000);

Socket socket = server.accept();

System.out.println("Client connected");

Client Example

import java.net.Socket;

Socket socket = new Socket("localhost", 5000);

This creates a simple client-server connection.

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8. Build Tools (Maven and Gradle)

Build tools help manage dependencies and compile projects.

Maven Example

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.33</version>
</dependency>

Maven automatically downloads the required library.

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9. Java Modules (JPMS)

The Java Platform Module System was introduced in Java 9.

Modules help organize large applications into smaller components.

module my.app.module {

    requires java.sql;

}

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10. Spring Framework Overview

The Spring Framework is the most popular Java framework for enterprise applications.

It simplifies:

• Dependency Injection
• Web development
• Database access
• Microservices

Spring Boot allows developers to build applications quickly.

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11. Microservices with Java

Microservices architecture breaks large systems into smaller services.

Each service runs independently and communicates through APIs.

Java technologies used for microservices include:

• Spring Boot
• Spring Cloud
• Docker
• Kubernetes

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12. Performance Optimization

Advanced Java developers also optimize performance.

Common techniques:

• Using efficient collections
• Reducing unnecessary object creation
• Using multithreading properly
• Profiling applications

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Conclusion

Advanced Java topics prepare developers to build scalable and modern applications. By understanding functional programming, database connectivity, networking, and modern frameworks like Spring, you can develop enterprise-level software systems.

With practice and real projects, these advanced skills will help you become a professional Java developer.