Detailed Breakdown of Key Java Features

Modules (Java 9+)

Modules provide a way to encapsulate code at a higher level than packages, helping organize large applications.

// In module-info.java
module com.myapp.core {
    requires java.sql;
    exports com.myapp.core.api;
    provides com.myapp.core.spi.Service with com.myapp.core.impl.ServiceImpl;
}

Benefits:

Strong encapsulation beyond package-level
Explicit dependencies between components
Improved application performance and security
Smaller runtime footprints with custom JRE creation

Records (Java 16+)

Records are immutable data carriers that reduce boilerplate code for simple data classes.

public record Person(String name, int age) {
    // Compiler automatically generates:
    // - Constructor
    // - Accessor methods (name(), age())
    // - equals(), hashCode(), toString()

    // You can add validation:
    public Person {
        if (age < 0) throw new IllegalArgumentException("Age cannot be negative");
    }
}

Benefits:

Concise data class declaration
Immutability by default
Automatic implementations of common methods

Pattern Matching (Java 17+)

Simplifies conditional logic with more powerful instanceof operations and switch expressions.

// Pattern matching with instanceof
if (obj instanceof String s) {
    // Can use 's' directly here without casting
    System.out.println(s.length());
}

// Pattern matching with switch (preview)
Object obj = getValue();
String result = switch (obj) {
    case Integer i -> "Integer: " + i;
    case String s -> "String: " + s;
    case null -> "null";
    default -> "Unknown";
};

Benefits:

More concise conditional code
Type-safe pattern testing and variable binding
Enhanced switch expressions

Text Blocks (Java 15+)

Multi-line string literals that preserve formatting without escape sequences.

String json = """
    {
        "name": "John Doe",
        "age": 30,
        "address": {
            "street": "123 Main St",
            "city": "Anytown"
        }
    }
    """;

Benefits:

Improved readability for multi-line strings
No need for most escape sequences
Better representation of formatted text like HTML, JSON, SQL

I/O and NIO

Java provides robust APIs for input/output operations and networking.

// Traditional I/O
try (FileReader fr = new FileReader("input.txt");
     BufferedReader br = new BufferedReader(fr)) {
    String line;
    while ((line = br.readLine()) != null) {
        System.out.println(line);
    }
}

// NIO (New I/O)
Path path = Paths.get("input.txt");
List<String> lines = Files.readAllLines(path);

// Networking
URL url = new URL("https://example.com");
try (InputStream is = url.openStream()) {
    // Read from website
}

Benefits:

Comprehensive file operations
Platform-independent path manipulation
Non-blocking I/O for high-performance applications
Channel-based operations for efficient data transfer

Sealed Classes (Java 17+)

Restrict which classes can extend a class or implement an interface.

public sealed class Shape permits Circle, Rectangle, Triangle {
    // Common shape functionality
}

public final class Circle extends Shape {
    // Circle-specific code
}

public final class Rectangle extends Shape {
    // Rectangle-specific code
}

public final class Triangle extends Shape {
    // Triangle-specific code
}

Benefits:

Control class hierarchy design
Better pattern matching exhaustiveness
Clear API design intent

JIT Compilation

Just-In-Time compilation optimizes Java bytecode at runtime.

How it works:

Java code is compiled to bytecode (.class files)
JVM initially interprets the bytecode
JIT compiler identifies frequently executed code ("hot spots")
Hot spots are compiled to native machine code for faster execution
Adaptive optimization improves performance over time

Benefits:

Improved execution speed
Runtime optimization based on actual usage patterns
Platform-specific optimizations

Optimized Collections

Java provides highly efficient implementations of common data structures.

// ArrayList - dynamic array
List<String> list = new ArrayList<>();

// HashMap - key-value storage
Map<String, Integer> map = new HashMap<>();

// Specialized collections
Queue<Task> tasks = new PriorityQueue<>();
Set<String> uniqueWords = new HashSet<>();

Optimizations include:

Dynamic resizing
Amortized constant-time operations
Thread-safe variants (ConcurrentHashMap, etc.)
Specialized implementations (EnumSet, ArrayDeque)

CompletableFuture

Enables asynchronous programming with composition capabilities.

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
    // This runs in a different thread
    return fetchDataFromRemoteAPI();
})
.thenApply(data -> {
    // Transform the data
    return processData(data);
})
.thenCombine(otherFuture, (result1, result2) -> {
    // Combine with another async operation
    return combineResults(result1, result2);
});

// Handle completion
future.whenComplete((result, error) -> {
    if (error != null) {
        handleError(error);
    } else {
        useResult(result);
    }
});

Benefits:

Non-blocking operations
Composable async operations
Elegant error handling
Thread management abstraction

Security Manager

Controls what operations applications can perform.

// Enable Security Manager
System.setSecurityManager(new SecurityManager());

// Define security policy in policy file
// grant permissions to specific code sources

Capabilities:

Control file system access
Restrict network operations
Limit reflection usage
Control thread creation and manipulation

Cryptography APIs

Java provides extensive support for encryption and security.

// Generate a key
KeyGenerator keyGen = KeyGenerator.getInstance("AES");
keyGen.init(256);
SecretKey secretKey = keyGen.generateKey();

// Encrypt data
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
byte[] encryptedData = cipher.doFinal(originalData);

// Message digests
MessageDigest md = MessageDigest.getInstance("SHA-256");
byte[] digest = md.digest(message.getBytes());

Features:

Symmetric and asymmetric encryption
Digital signatures
Secure random number generation
Certificate management

Access Control

Java provides multiple layers of security through class loaders and access modifiers.

Class Loaders:

Load classes dynamically at runtime
Enforce namespace separation
Validate bytecode
Support custom class loading policies

Access modifiers:

public: Accessible everywhere
protected: Accessible in the package and subclasses
Default (no modifier): Accessible only in the package
private: Accessible only in the class

These security mechanisms work together to create a robust platform for developing secure applications.