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Java · IntermediateSnippet

Functional Interfaces and Lambda Expressions

Functional interfaces contain exactly one abstract method and can be implemented using lambda expressions to provide a concise way to represent anonymous functions.

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@FunctionalInterface
interface MathOperation {
    int operate(int a, int b);
}
 
public class LambdaExample {
    public static void main(String[] args) {
        MathOperation addition = (a, b) -> a + b;
        System.out.println("Result: " + addition.operate(10, 5));
    }
}

FunctionsSyntax

Java · IntermediateSnippet

Immutability with Records

Records are a special kind of class that acts as a transparent carrier for immutable data, automatically generating constructors, accessors, equals, and hashCode.

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public record User(int id, String name) {}
 
public class RecordDemo {
    public static void main(String[] args) {
        User user = new User(1, "Alice");
        System.out.println(user.name());
        System.out.println(user);
    }
}

OOPSyntax

Java · IntermediateSnippet

Stream API for Collection Processing

Streams allow functional-style operations on sequences of elements, such as filtering, mapping, and reducing collections efficiently.

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import java.util.List;
import java.util.stream.Collectors;
 
public class StreamExample {
    public static void main(String[] args) {
        List<String> names = List.of("Anna", "Bob", "Charlie", "David");
        List<String> filtered = names.stream()
                                     .filter(n -> n.length() > 4)
                                     .collect(Collectors.toList());
        System.out.println(filtered);
    }
}

FunctionsPerformance

Java · IntermediateSnippet

Safely Handling Null with Optional

The Optional class is a container object used to represent the presence or absence of a value, helping to avoid NullPointerExceptions.

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import java.util.Optional;
 
public class OptionalDemo {
    public static void main(String[] args) {
        Optional<String> name = Optional.ofNullable(getName());
        String result = name.map(String::toUpperCase)
                            .orElse("DEFAULT");
        System.out.println(result);
    }
 
    static String getName() { return null; }
}

Best PracticesError Handling

Java · IntermediateSnippet

Automatic Resource Management

The try-with-resources statement ensures that each resource is closed at the end of the statement, preventing memory leaks and resource exhaustion.

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import java.io.*;
 
public class TryWithResources {
    public static void main(String[] args) {
        try (BufferedReader br = new BufferedReader(new FileReader("test.txt"))) {
            System.out.println(br.readLine());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Error HandlingBest Practices

Java · IntermediateSnippet

Exception Chaining for Better Debugging

Exception chaining allows you to wrap a low-level exception (like IOException) into a higher-level business exception while preserving the original cause. This keeps the stack trace intact for debugging.

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public void loadConfig() throws DataException {
    try {
        Files.readAllLines(Paths.get("config.txt"));
    } catch (IOException e) {
        throw new DataException("Configuration file missing", e);
    }
}

Error HandlingBest Practices

Java · IntermediateSnippet

Custom Annotations for Metadata

Custom annotations allow you to add metadata to your code that can be processed at runtime via Reflection. This is often used by frameworks for cross-cutting concerns like logging or validation.

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@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface LogExecutionTime {
    String value() default "Generic";
}

OOPBest Practices

Java · IntermediateSnippet

Memory Visibility with the volatile Keyword

The volatile keyword ensures that changes to a variable are always visible to all threads immediately. It prevents threads from caching the variable locally, ensuring they always read the latest value from main memory.

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public class SharedFlag {
    private volatile boolean active = true;
 
    public void stop() { active = false; }
 
    public void work() {
        while (active) { /* perform task */ }
    }
}

Async & ConcurrencyMemory Management