Go vs Java: Backend Language Comparison for 2025

Introduction

Go and Java represent two generations of backend development. Java, with over 25 years of enterprise dominance, offers a mature ecosystem and proven scalability. Go, designed at Google in 2009, brings modern simplicity and exceptional concurrency. Both power some of the world's largest systems—Java runs LinkedIn, Netflix, and countless banks, while Go powers Docker, Kubernetes, and Uber's high-throughput services.

In this guide, we'll compare:

• Language design philosophy
• Performance and resource usage
• Concurrency models
• Ecosystem and tooling
• Real-world adoption and use cases

Language Philosophy

Java: Write Once, Run Anywhere

// Java's object-oriented, verbose approach
public class UserService {
    private final UserRepository userRepository;
    private final EmailService emailService;

    // Constructor injection for DI
    public UserService(UserRepository userRepository, EmailService emailService) {
        this.userRepository = userRepository;
        this.emailService = emailService;
    }

    public User createUser(CreateUserRequest request) throws UserCreationException {
        // Validate request
        if (request.getEmail() == null || request.getEmail().isEmpty()) {
            throw new IllegalArgumentException("Email is required");
        }

        // Check for existing user
        Optional<User> existing = userRepository.findByEmail(request.getEmail());
        if (existing.isPresent()) {
            throw new UserAlreadyExistsException("Email already registered");
        }

        // Create user
        User user = new User();
        user.setEmail(request.getEmail().toLowerCase());
        user.setName(request.getName());
        user.setCreatedAt(LocalDateTime.now());
        user.setActive(true);

        User savedUser = userRepository.save(user);

        // Send welcome email
        emailService.sendWelcomeEmail(savedUser);

        return savedUser;
    }
}

Go: Simple, Fast, Reliable

// Go's straightforward, explicit approach
type UserService struct {
    repo  UserRepository
    email EmailService
}

func NewUserService(repo UserRepository, email EmailService) *UserService {
    return &UserService{repo: repo, email: email}
}

func (s *UserService) CreateUser(req CreateUserRequest) (*User, error) {
    // Validate request
    if req.Email == "" {
        return nil, errors.New("email is required")
    }

    // Check for existing user
    existing, err := s.repo.FindByEmail(req.Email)
    if err != nil && !errors.Is(err, ErrNotFound) {
        return nil, fmt.Errorf("checking existing user: %w", err)
    }
    if existing != nil {
        return nil, ErrUserAlreadyExists
    }

    // Create user
    user := &User{
        Email:     strings.ToLower(req.Email),
        Name:      req.Name,
        CreatedAt: time.Now(),
        Active:    true,
    }

    if err := s.repo.Save(user); err != nil {
        return nil, fmt.Errorf("saving user: %w", err)
    }

    // Send welcome email (fire and forget)
    go s.email.SendWelcomeEmail(user)

    return user, nil
}

Syntax Comparison

Variable Declaration

// Java
String name = "Tushar";
int age = 25;
List<String> tags = new ArrayList<>();
Map<String, Object> metadata = new HashMap<>();

// Java 10+ with var (type inference)
var name = "Tushar";
var tags = new ArrayList<String>();

// Records (Java 14+)
public record User(int id, String name, String email) {}

// Go
var name string = "Tushar"
var age int = 25
var tags []string
metadata := make(map[string]interface{})

// Short declaration (type inference)
name := "Tushar"
tags := []string{}

// Struct
type User struct {
    ID    int
    Name  string
    Email string
}

Error Handling

// Java - Exception-based
public User getUser(int id) throws UserNotFoundException {
    return userRepository.findById(id)
        .orElseThrow(() -> new UserNotFoundException("User not found: " + id));
}

// Try-catch
try {
    User user = userService.getUser(123);
    processUser(user);
} catch (UserNotFoundException e) {
    logger.warn("User not found", e);
    return Response.notFound().build();
} catch (Exception e) {
    logger.error("Unexpected error", e);
    return Response.serverError().build();
}

// Try-with-resources
try (Connection conn = dataSource.getConnection();
     PreparedStatement stmt = conn.prepareStatement(sql)) {
    stmt.setInt(1, userId);
    try (ResultSet rs = stmt.executeQuery()) {
        // Process results
    }
}

// Go - Explicit error returns
func (s *Service) GetUser(id int) (*User, error) {
    user, err := s.repo.FindByID(id)
    if err != nil {
        if errors.Is(err, ErrNotFound) {
            return nil, fmt.Errorf("user not found: %d", id)
        }
        return nil, fmt.Errorf("fetching user: %w", err)
    }
    return user, nil
}

// Error handling
user, err := userService.GetUser(123)
if err != nil {
    if errors.Is(err, ErrNotFound) {
        log.Printf("User not found: %v", err)
        return NotFoundResponse()
    }
    log.Printf("Unexpected error: %v", err)
    return ServerErrorResponse()
}
processUser(user)

// Defer for cleanup
func processFile(path string) error {
    f, err := os.Open(path)
    if err != nil {
        return err
    }
    defer f.Close()  // Guaranteed to run

    // Process file
    return nil
}

Interfaces

// Java - Explicit interface implementation
public interface PaymentProcessor {
    PaymentResult process(Payment payment);
    void refund(String transactionId);
}

public class StripeProcessor implements PaymentProcessor {
    @Override
    public PaymentResult process(Payment payment) {
        // Implementation
    }

    @Override
    public void refund(String transactionId) {
        // Implementation
    }
}

// Using the interface
PaymentProcessor processor = new StripeProcessor();

// Go - Implicit interface implementation (structural typing)
type PaymentProcessor interface {
    Process(payment Payment) (PaymentResult, error)
    Refund(transactionID string) error
}

type StripeProcessor struct {
    apiKey string
}

// No "implements" keyword - just define the methods
func (s *StripeProcessor) Process(payment Payment) (PaymentResult, error) {
    // Implementation
}

func (s *StripeProcessor) Refund(transactionID string) error {
    // Implementation
}

// Using the interface
var processor PaymentProcessor = &StripeProcessor{apiKey: "sk_xxx"}

Performance Comparison

Benchmarks

HTTP Server Benchmark (JSON API, 10K concurrent connections)
============================================================

Metric              Go (net/http)    Java (Spring Boot)   Java (Quarkus)
Requests/sec        120,000          45,000               85,000
Latency (p99)       5ms              25ms                 12ms
Memory Usage        50MB             300MB                150MB
Startup Time        10ms             3,000ms              500ms
Container Size      15MB             200MB                80MB

Note: Results vary based on configuration and workload

Memory Usage

Memory Footprint Comparison
===========================

Scenario                    Go          Java (G1 GC)    Java (ZGC)
──────────────────────────────────────────────────────────────────
Hello World                 2MB         50MB            60MB
REST API (idle)             15MB        200MB           220MB
REST API (under load)       50MB        400MB           350MB
10M objects in memory       200MB       500MB           450MB
Peak during GC              +10%        +50%            +15%

Garbage Collection

// Java GC Options
// G1GC (default since Java 9) - balanced throughput/latency
// -XX:+UseG1GC -XX:MaxGCPauseMillis=200

// ZGC - ultra-low latency (< 1ms pauses)
// -XX:+UseZGC -XX:+ZGenerational

// Shenandoah - low latency alternative
// -XX:+UseShenandoahGC

// GraalVM Native Image - AOT compilation, no JVM overhead
// native-image -jar myapp.jar

// Go GC - concurrent, low-latency by default
// GOGC=100 (default) - trigger GC when heap doubles
// GOMEMLIMIT=1GiB - soft memory limit (Go 1.19+)

// Minimal tuning needed - Go's GC is designed for low latency
// Typical pause times: < 1ms

Concurrency Models

Java Concurrency

// Traditional threading
public class UserProcessor {
    private final ExecutorService executor = Executors.newFixedThreadPool(10);

    public List<UserResult> processUsers(List<User> users) {
        List<Future<UserResult>> futures = users.stream()
            .map(user -> executor.submit(() -> processUser(user)))
            .collect(Collectors.toList());

        return futures.stream()
            .map(this::getFutureResult)
            .collect(Collectors.toList());
    }

    private UserResult getFutureResult(Future<UserResult> future) {
        try {
            return future.get(30, TimeUnit.SECONDS);
        } catch (Exception e) {
            throw new RuntimeException("Processing failed", e);
        }
    }
}

// CompletableFuture (Java 8+)
public CompletableFuture<OrderResult> processOrder(Order order) {
    return CompletableFuture
        .supplyAsync(() -> validateOrder(order))
        .thenCompose(validated -> chargePayment(validated))
        .thenCompose(charged -> createShipment(charged))
        .thenApply(shipped -> new OrderResult(shipped))
        .exceptionally(ex -> {
            logger.error("Order processing failed", ex);
            return OrderResult.failed(ex.getMessage());
        });
}

// Virtual Threads (Java 21+) - Project Loom
public void processWithVirtualThreads(List<User> users) {
    try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
        List<Future<UserResult>> futures = users.stream()
            .map(user -> executor.submit(() -> processUser(user)))
            .toList();

        // Virtual threads are lightweight - can have millions
        for (Future<UserResult> future : futures) {
            UserResult result = future.get();
            // Process result
        }
    }
}

// Structured Concurrency (Java 21 Preview)
public OrderResult processOrderStructured(Order order) throws Exception {
    try (var scope = new StructuredTaskScope.ShutdownOnFailure()) {
        Subtask<ValidatedOrder> validation = scope.fork(() -> validateOrder(order));
        Subtask<InventoryCheck> inventory = scope.fork(() -> checkInventory(order));

        scope.join();
        scope.throwIfFailed();

        return new OrderResult(validation.get(), inventory.get());
    }
}

Go Concurrency

// Goroutines and channels
func ProcessUsers(users []User) []UserResult {
    results := make(chan UserResult, len(users))

    for _, user := range users {
        go func(u User) {
            results <- processUser(u)
        }(user)
    }

    var output []UserResult
    for i := 0; i < len(users); i++ {
        output = append(output, <-results)
    }
    return output
}

// Worker pool pattern
func ProcessWithWorkerPool(users []User, numWorkers int) []UserResult {
    jobs := make(chan User, len(users))
    results := make(chan UserResult, len(users))

    // Start workers
    var wg sync.WaitGroup
    for w := 0; w < numWorkers; w++ {
        wg.Add(1)
        go func() {
            defer wg.Done()
            for user := range jobs {
                results <- processUser(user)
            }
        }()
    }

    // Send jobs
    for _, user := range users {
        jobs <- user
    }
    close(jobs)

    // Wait and collect
    go func() {
        wg.Wait()
        close(results)
    }()

    var output []UserResult
    for result := range results {
        output = append(output, result)
    }
    return output
}

// Context for cancellation and timeouts
func ProcessOrderWithTimeout(ctx context.Context, order Order) (*OrderResult, error) {
    ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
    defer cancel()

    // Create channels for concurrent operations
    validationCh := make(chan ValidationResult, 1)
    inventoryCh := make(chan InventoryResult, 1)
    errCh := make(chan error, 2)

    // Start concurrent operations
    go func() {
        result, err := validateOrder(ctx, order)
        if err != nil {
            errCh <- err
            return
        }
        validationCh <- result
    }()

    go func() {
        result, err := checkInventory(ctx, order)
        if err != nil {
            errCh <- err
            return
        }
        inventoryCh <- result
    }()

    // Wait for results or errors
    var validation ValidationResult
    var inventory InventoryResult

    for i := 0; i < 2; i++ {
        select {
        case <-ctx.Done():
            return nil, ctx.Err()
        case err := <-errCh:
            return nil, err
        case validation = <-validationCh:
        case inventory = <-inventoryCh:
        }
    }

    return &OrderResult{Validation: validation, Inventory: inventory}, nil
}

// errgroup for structured concurrency
func ProcessOrderWithErrgroup(ctx context.Context, order Order) (*OrderResult, error) {
    g, ctx := errgroup.WithContext(ctx)

    var validation ValidationResult
    var inventory InventoryResult

    g.Go(func() error {
        var err error
        validation, err = validateOrder(ctx, order)
        return err
    })

    g.Go(func() error {
        var err error
        inventory, err = checkInventory(ctx, order)
        return err
    })

    if err := g.Wait(); err != nil {
        return nil, err
    }

    return &OrderResult{Validation: validation, Inventory: inventory}, nil
}

Concurrency Comparison

Concurrency Model Comparison
============================

Aspect              Go                      Java (Traditional)    Java (Virtual Threads)
────────────────────────────────────────────────────────────────────────────────────────
Unit                Goroutine               Thread                Virtual Thread
Memory per unit     ~2KB                    ~1MB                  ~1KB
Max concurrent      Millions                Thousands             Millions
Scheduling          Go runtime (M:N)        OS (1:1)              JVM (M:N)
Communication       Channels (CSP)          Shared memory         Shared memory
Synchronization     Mutex, channels         synchronized, locks   synchronized, locks
Learning curve      Moderate                Complex               Moderate
Debugging           Race detector           Thread dumps          Thread dumps

Web Frameworks

Java: Spring Boot

// Spring Boot REST API
@RestController
@RequestMapping("/api/users")
public class UserController {

    private final UserService userService;

    public UserController(UserService userService) {
        this.userService = userService;
    }

    @GetMapping
    public ResponseEntity<List<UserDTO>> listUsers(
            @RequestParam(defaultValue = "0") int page,
            @RequestParam(defaultValue = "10") int size) {
        Page<User> users = userService.findAll(PageRequest.of(page, size));
        List<UserDTO> dtos = users.map(UserDTO::fromUser).getContent();
        return ResponseEntity.ok(dtos);
    }

    @GetMapping("/{id}")
    public ResponseEntity<UserDTO> getUser(@PathVariable Long id) {
        return userService.findById(id)
            .map(UserDTO::fromUser)
            .map(ResponseEntity::ok)
            .orElse(ResponseEntity.notFound().build());
    }

    @PostMapping
    public ResponseEntity<UserDTO> createUser(@Valid @RequestBody CreateUserRequest request) {
        User user = userService.create(request);
        URI location = URI.create("/api/users/" + user.getId());
        return ResponseEntity.created(location).body(UserDTO.fromUser(user));
    }

    @PutMapping("/{id}")
    public ResponseEntity<UserDTO> updateUser(
            @PathVariable Long id,
            @Valid @RequestBody UpdateUserRequest request) {
        return userService.update(id, request)
            .map(UserDTO::fromUser)
            .map(ResponseEntity::ok)
            .orElse(ResponseEntity.notFound().build());
    }

    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteUser(@PathVariable Long id) {
        if (userService.delete(id)) {
            return ResponseEntity.noContent().build();
        }
        return ResponseEntity.notFound().build();
    }

    @ExceptionHandler(ValidationException.class)
    public ResponseEntity<ErrorResponse> handleValidation(ValidationException ex) {
        return ResponseEntity.badRequest()
            .body(new ErrorResponse(ex.getMessage()));
    }
}

// Spring WebFlux (Reactive)
@RestController
@RequestMapping("/api/users")
public class ReactiveUserController {

    private final ReactiveUserService userService;

    @GetMapping(produces = MediaType.APPLICATION_NDJSON_VALUE)
    public Flux<UserDTO> streamUsers() {
        return userService.findAll()
            .map(UserDTO::fromUser);
    }

    @GetMapping("/{id}")
    public Mono<ResponseEntity<UserDTO>> getUser(@PathVariable Long id) {
        return userService.findById(id)
            .map(UserDTO::fromUser)
            .map(ResponseEntity::ok)
            .defaultIfEmpty(ResponseEntity.notFound().build());
    }
}

Go: Gin/Echo

// Gin REST API
func SetupRouter(userService *UserService) *gin.Engine {
    r := gin.Default()

    users := r.Group("/api/users")
    {
        users.GET("", listUsers(userService))
        users.GET("/:id", getUser(userService))
        users.POST("", createUser(userService))
        users.PUT("/:id", updateUser(userService))
        users.DELETE("/:id", deleteUser(userService))
    }

    return r
}

func listUsers(s *UserService) gin.HandlerFunc {
    return func(c *gin.Context) {
        page, _ := strconv.Atoi(c.DefaultQuery("page", "0"))
        size, _ := strconv.Atoi(c.DefaultQuery("size", "10"))

        users, err := s.FindAll(page, size)
        if err != nil {
            c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
            return
        }

        dtos := make([]UserDTO, len(users))
        for i, u := range users {
            dtos[i] = UserDTOFromUser(u)
        }

        c.JSON(http.StatusOK, dtos)
    }
}

func getUser(s *UserService) gin.HandlerFunc {
    return func(c *gin.Context) {
        id, err := strconv.ParseInt(c.Param("id"), 10, 64)
        if err != nil {
            c.JSON(http.StatusBadRequest, gin.H{"error": "invalid id"})
            return
        }

        user, err := s.FindByID(id)
        if err != nil {
            if errors.Is(err, ErrNotFound) {
                c.JSON(http.StatusNotFound, gin.H{"error": "user not found"})
                return
            }
            c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
            return
        }

        c.JSON(http.StatusOK, UserDTOFromUser(user))
    }
}

func createUser(s *UserService) gin.HandlerFunc {
    return func(c *gin.Context) {
        var req CreateUserRequest
        if err := c.ShouldBindJSON(&req); err != nil {
            c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
            return
        }

        user, err := s.Create(req)
        if err != nil {
            c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
            return
        }

        c.Header("Location", fmt.Sprintf("/api/users/%d", user.ID))
        c.JSON(http.StatusCreated, UserDTOFromUser(user))
    }
}

// Middleware
func AuthMiddleware(authService *AuthService) gin.HandlerFunc {
    return func(c *gin.Context) {
        token := c.GetHeader("Authorization")
        if token == "" {
            c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "missing token"})
            return
        }

        user, err := authService.ValidateToken(token)
        if err != nil {
            c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
            return
        }

        c.Set("user", user)
        c.Next()
    }
}

Ecosystem Comparison

Ecosystem Comparison
====================

Category           Java                          Go
─────────────────────────────────────────────────────────────────────
Build Tool         Maven, Gradle                 go build (built-in)
Dependency Mgmt    Maven Central, JitPack        Go Modules (built-in)
Web Frameworks     Spring Boot, Quarkus, Micronaut  Gin, Echo, Fiber, Chi
ORM/Database       Hibernate, JPA, jOOQ          GORM, sqlx, Ent
Testing            JUnit, Mockito, TestContainers   testing (built-in), testify
HTTP Client        RestTemplate, WebClient       net/http (built-in)
JSON               Jackson, Gson                 encoding/json (built-in)
Logging            Logback, Log4j2               log/slog, zerolog
DI/IoC             Spring, Guice, Dagger         wire, fx
gRPC               grpc-java                     grpc-go
Message Queue      Spring Kafka, RabbitMQ client kafka-go, amqp
Cloud SDK          AWS SDK, GCP SDK              aws-sdk-go, cloud.google.com
Observability      Micrometer, OpenTelemetry     OpenTelemetry, Prometheus
IDE Support        IntelliJ IDEA (excellent)     GoLand, VS Code (good)

Enterprise Adoption

Enterprise Adoption 2025
========================

Java (Traditional Enterprise)
- Banks: Goldman Sachs, JP Morgan, Deutsche Bank
- Tech: Netflix, LinkedIn, Twitter, Uber
- E-commerce: Amazon, eBay, Alibaba
- Enterprise: SAP, Oracle, Salesforce

Go (Cloud Native/Modern)
- Cloud: Google, Cloudflare, DigitalOcean
- DevOps: Docker, Kubernetes, Terraform
- Streaming: Twitch, SoundCloud
- Finance: PayPal, American Express (new services)
- Tech: Uber (high-throughput), Dropbox, Slack

Trend: Many Java shops adding Go for specific use cases
- Microservices with high concurrency needs
- CLI tools and DevOps automation
- Container and Kubernetes tooling

Build and Deployment

Java

<!-- pom.xml -->
<project>
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>myapp</artifactId>
    <version>1.0.0</version>
    <packaging>jar</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.0</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

# Java Dockerfile
FROM eclipse-temurin:21-jre-alpine
WORKDIR /app
COPY target/myapp.jar app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "app.jar"]

# Multi-stage build
FROM eclipse-temurin:21-jdk-alpine AS builder
WORKDIR /app
COPY . .
RUN ./mvnw package -DskipTests

FROM eclipse-temurin:21-jre-alpine
WORKDIR /app
COPY --from=builder /app/target/*.jar app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "app.jar"]

# GraalVM Native Image
FROM ghcr.io/graalvm/native-image:21 AS builder
WORKDIR /app
COPY . .
RUN ./mvnw -Pnative native:compile

FROM alpine:3.19
COPY --from=builder /app/target/myapp /app/myapp
ENTRYPOINT ["/app/myapp"]

Go

// go.mod
module github.com/example/myapp

go 1.21

require (
    github.com/gin-gonic/gin v1.9.1
    github.com/lib/pq v1.10.9
)

# Go Dockerfile (simple)
FROM golang:1.21-alpine AS builder
WORKDIR /app
COPY go.mod go.sum ./
RUN go mod download
COPY . .
RUN CGO_ENABLED=0 GOOS=linux go build -o myapp .

FROM alpine:3.19
RUN apk --no-cache add ca-certificates
WORKDIR /app
COPY --from=builder /app/myapp .
EXPOSE 8080
ENTRYPOINT ["./myapp"]

# Minimal image with scratch
FROM golang:1.21-alpine AS builder
WORKDIR /app
COPY . .
RUN CGO_ENABLED=0 go build -ldflags="-s -w" -o myapp .

FROM scratch
COPY --from=builder /app/myapp /myapp
COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
EXPOSE 8080
ENTRYPOINT ["/myapp"]

Build Comparison
================

Metric              Java (Spring)      Java (Native)     Go
──────────────────────────────────────────────────────────────
Build time          30-60s             5-10min           5-15s
JAR/Binary size     50-100MB           50-80MB           10-20MB
Docker image        200-400MB          80-150MB          15-50MB
Startup time        2-5s               0.1-0.5s          0.01-0.1s
Memory (idle)       200-400MB          50-100MB          10-30MB

Decision Matrix

When to Choose Which
====================

Scenario                          Java        Go        Notes
────────────────────────────────────────────────────────────────────────
Existing Java team                ✓✓✓         ✓         Leverage expertise
Greenfield microservices          ✓✓          ✓✓✓       Go's simplicity wins
High-throughput APIs              ✓✓          ✓✓✓       Go's performance
Complex business logic            ✓✓✓         ✓✓        Java's expressiveness
Enterprise integration            ✓✓✓         ✓         Java's mature ecosystem
Kubernetes/Cloud native           ✓✓          ✓✓✓       Go dominates this space
Big Data processing               ✓✓✓         ✓         Spark, Flink ecosystem
CLI tools                         ✓           ✓✓✓       Single binary deployment
Android development               ✓✓✓         ✗         Java/Kotlin only
Memory-constrained                ✓           ✓✓✓       Go's efficiency
Team learning curve               ✓✓          ✓✓✓       Go is simpler
Long-term maintenance             ✓✓✓         ✓✓        Java's stability

✓✓✓ = Excellent  ✓✓ = Good  ✓ = Adequate  ✗ = Not recommended

Migration Strategies

Java to Go Migration

// Common patterns when migrating from Java to Go

// Java-style builder pattern (avoid in Go)
// Instead, use functional options:
type ServerOption func(*Server)

func WithPort(port int) ServerOption {
    return func(s *Server) {
        s.port = port
    }
}

func WithTimeout(d time.Duration) ServerOption {
    return func(s *Server) {
        s.timeout = d
    }
}

func NewServer(opts ...ServerOption) *Server {
    s := &Server{
        port:    8080,
        timeout: 30 * time.Second,
    }
    for _, opt := range opts {
        opt(s)
    }
    return s
}

// Usage
server := NewServer(
    WithPort(3000),
    WithTimeout(60*time.Second),
)

Conclusion

Both Java and Go are excellent choices for backend development in 2025:

Choose Java when:

• Building complex enterprise applications
• Need mature ecosystem and extensive libraries
• Team has Java expertise
• Integrating with existing Java systems
• Building Android applications

Choose Go when:

• Performance and efficiency are critical
• Building microservices for Kubernetes
• Creating CLI tools or system utilities
• Want fast build times and simple deployment
• Need high concurrency with simple code

Consider both when:

• Building a microservices architecture
• Different services have different requirements
• Gradual migration from monolith

The trend shows Java remaining strong in enterprise while Go grows in cloud-native and DevOps tooling. Many organizations successfully use both languages, choosing the right tool for each specific service.

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