# Gradle проект с авто-структурой
mkdir my_java_app && cd my_java_app
gradle init --type java-application --dsl groovy --test-framework junit-jupiter

# быстрый запуск + тесты
./gradlew test
./gradlew run

❌ ПЛОХО: упадёт, если s == null
if (s.equals("OK")) {
    handle();
}

// ✅ ЛУЧШЕ: safe equals (null-safe)
if ("OK".equals(s)) {
    handle();
}

// ✅ Универсально: сравнение объектов + null-safe
if (Objects.equals(s, "OK")) {
    handle();
}

"phone": null,
"email": null

<!-- Dependency -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-mail</artifactId>
</dependency>
⚡️<!-- application.properties -->
spring.mail.host=smtp.gmail.com
spring.mail.port=587
spring.mail.username=your_email@gmail.com
spring.mail.password=your_app_password
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.starttls.enable=true

// Service
@Autowired
private JavaMailSender mailSender;

public void sendEmail(String to, String subject, String text) {
    SimpleMailMessage message = new SimpleMailMessage();
    message.setTo(to);
    message.setSubject(subject);
    message.setText(text);
    message.setFrom("your_email@gmail.com");

    mailSender.send(message);
}

ThreadLocal<Integer> counter =
    ThreadLocal.withInitial(() -> 0);

counter.get();  // 0
counter.set(70);
counter.get();  // 70

@SpringBootApplication(
    exclude = {
        DataSourceAutoConfiguration.class,
        HibernateJpaAutoConfiguration.class
    }
)
public class MyApplication {
    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class, args);
    }
}

@Bean
public CommonsRequestLoggingFilter logFilter() {
    CommonsRequestLoggingFilter filter = new CommonsRequestLoggingFilter();
    filter.setIncludeQueryString(true);
    filter.setIncludeHeaders(true);
    filter.setIncludePayload(true);
    filter.setMaxPayloadLength(1000);
    filter.setAfterMessagePrefix("COMPLETE REQUEST: ");
    return filter;
}

POST /login
{
  "username": "john",
  "password": "mypassword"
}

import java.io.IOException;
import java.nio.file.*;
import java.util.stream.Stream;

public class Main {
    public static void main(String[] args) {
        Path startPath = Paths.get("src");

        try (Stream<Path> paths = Files.walk(startPath)) {
            paths
                .filter(Files::isRegularFile)
                .filter(path -> path.toString().endsWith(".java"))
                .forEach(System.out::println);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Instant a = Instant.parse("2025-10-01T10:42:11Z");
Instant b = Instant.parse("2025-10-01T10:42:44Z");

boolean sameMinute =
    a.truncatedTo(ChronoUnit.MINUTES)
     .equals(b.truncatedTo(ChronoUnit.MINUTES));

System.out.println(sameMinute); // true