Welcome to Advanced Java Tutorials

Welcome to the advanced tutorials section of Java World. Here, you’ll find resources to help you master advanced Java programming concepts. Our tutorials cover a wide range of topics that will enhance your coding capabilities and prepare you for complex Java projects.

Section 1: Advanced Object-Oriented Programming

Generics

Generics in Java allow you to define classes, interfaces, and methods with type parameters. This tutorial will teach you how to use generics.

class GenericClass {
    private T value;
    
    public void setValue(T value) {
        this.value = value;
    }
    
    public T getValue() {
        return value;
    }
}

public class Main {
    public static void main(String[] args) {
        GenericClass stringInstance = new GenericClass<>();
        stringInstance.setValue("Hello");
        System.out.println(stringInstance.getValue());
        
        GenericClass integerInstance = new GenericClass<>();
        integerInstance.setValue(123);
        System.out.println(integerInstance.getValue());
    }
}
      

Annotations

Annotations in Java provide metadata about the program. This tutorial will teach you how to use annotations.

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

@Retention(RetentionPolicy.RUNTIME)
@interface MyAnnotation {
    String value();
}

public class Main {
    @MyAnnotation(value = "Hello, World!")
    public void myMethod() {
        System.out.println("This is my method.");
    }
    
    public static void main(String[] args) throws Exception {
        Main main = new Main();
        Method method = main.getClass().getMethod("myMethod");
        MyAnnotation annotation = method.getAnnotation(MyAnnotation.class);
        System.out.println("Annotation value: " + annotation.value());
    }
}
      

Reflection

Reflection in Java is a powerful mechanism that allows the inspection and manipulation of classes, interfaces, fields, and methods at runtime.

import java.lang.reflect.Method;

public class Main {
    public static void main(String[] args) throws Exception {
        Class<?> cls = Class.forName("java.lang.String");
        Method method = cls.getMethod("substring", int.class);
        String result = (String) method.invoke("Hello, World!", 7);
        System.out.println(result); // Outputs: World!
    }
}
      

Section 2: Advanced Data Structures and Algorithms

Advanced Collections

Java Collections Framework provides advanced collections like ConcurrentHashMap and CopyOnWriteArrayList for use in concurrent environments.

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;

public class Main {
    public static void main(String[] args) {
        ConcurrentHashMap<String, Integer> map = new ConcurrentHashMap<>();
        map.put("One", 1);
        map.put("Two", 2);
        System.out.println(map);
        
        CopyOnWriteArrayList list = new CopyOnWriteArrayList<>();
        list.add("One");
        list.add("Two");
        System.out.println(list);
    }
}
      

Streams API

The Streams API in Java provides a functional approach to processing sequences of elements. This tutorial will teach you how to use the Streams API.

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        List names = Arrays.asList("Alice", "Bob", "Charlie");
        List upperCaseNames = names.stream()
                                           .map(String::toUpperCase)
                                           .collect(Collectors.toList());
        upperCaseNames.forEach(System.out::println);
    }
}
      

Lambda Expressions

Lambda expressions in Java provide a clear and concise way to represent one method interface using an expression.

@FunctionalInterface
interface MyFunctionalInterface {
    void display();
}

public class Main {
    public static void main(String[] args) {
        MyFunctionalInterface msg = () -> {
            System.out.println("Hello, this is a lambda expression.");
        };
        msg.display();
    }
}
      

Section 3: Advanced Concurrency

Thread Pools

Thread pools are used to manage a pool of worker threads. This tutorial will teach you how to use thread pools in Java.

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Main {
    public static void main(String[] args) {
        ExecutorService executor = Executors.newFixedThreadPool(5);
        
        for (int i = 0; i < 10; i++) {
            Runnable worker = new WorkerThread("" + i);
            executor.execute(worker);
        }
        executor.shutdown();
        while (!executor.isTerminated()) {
        }
        System.out.println("Finished all threads");
    }
}

class WorkerThread implements Runnable {
    private String message;
    
    public WorkerThread(String message) {
        this.message = message;
    }
    
    public void run() {
        System.out.println(Thread.currentThread().getName() + " (Start) message = " + message);
        processMessage();
        System.out.println(Thread.currentThread().getName() + " (End)");
    }
    
    private void processMessage() {
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}
      

Concurrency Utilities

Java provides several utilities for concurrent programming, such as CountDownLatch and CyclicBarrier.

import java.util.concurrent.CountDownLatch;

public class Main {
    public static void main(String[] args) throws InterruptedException {
        CountDownLatch latch = new CountDownLatch(3);
        
        Runnable task = () -> {
            System.out.println(Thread.currentThread().getName() + " is running");
            latch.countDown();
        };
        
        new Thread(task).start();
        new Thread(task).start();
        new Thread(task).start();
        
        latch.await();
        System.out.println("All threads have finished");
    }
}
      

Advanced Synchronization

Advanced synchronization techniques include using explicit locks, such as ReentrantLock, and concurrent collections for thread-safe operations.

import java.util.concurrent.locks.ReentrantLock;

public class Main {
    public static void main(String[] args) {
        ReentrantLock lock = new ReentrantLock();
        
        Runnable task = () -> {
            lock.lock();
            try {
                System.out.println(Thread.currentThread().getName() + " has acquired the lock");
            } finally {
                lock.unlock();
            }
        };
        
        new Thread(task).start();
        new Thread(task).start();
    }
}
      

Continue exploring our advanced tutorials to master Java programming.