Java | Фишки и трюки

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

public class JCAExample {

    public static void main(String[] args) throws Exception {
        // Генерируем секретный ключ
        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
        keyGenerator.init(128);
        SecretKey secretKey = keyGenerator.generateKey();

        // Шифруем данные
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
        byte[] encryptedData = cipher.doFinal("Hello, World!".getBytes());

        // Дешифруем данные
        cipher.init(Cipher.DECRYPT_MODE, secretKey);
        byte[] decryptedData = cipher.doFinal(encryptedData);

        System.out.println("Original data: " + new String(decryptedData));
    }
}

final String pig = "length: 10";
final String dog = "length: " + pig.length();
System.out.println(pig == dog);

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
 
public class HelloWorld extends Application {
 
    @Override
    public void start(Stage primaryStage) {
        Button btn = new Button();
        btn.setText("Hello World");
 
        StackPane root = new StackPane();
        root.getChildren().add(btn);
 
        Scene scene = new Scene(root, 300, 250);
 
        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(scene);
        primaryStage.show();
    }
 
    public static void main(String[] args) {
        launch(args);
    }
}

import java.util.regex.*;

public class RegexExample {
    public static void main(String[] args) {
        String text = "The cat in the hat";

        // Компилируем регулярное выражение
        Pattern pattern = Pattern.compile("\\bcat\\b");

        // Создаем Matcher, сравниваем его с текстом и выводим результат
        Matcher matcher = pattern.matcher(text);
        if (matcher.find()) {
            System.out.println("Найдено совпадение!");
        } else {
            System.out.println("Совпадений не найдено");
        }
    }
}

public class ShadesOfGray {
    public static void main(String[] args) {
        System.out.println(X.Y.Z);
    }
}

class X {
    static class Y {
        static String Z = "BLACK";
    }
    static C Y = new C();
}

class C {
    String Z = "WHITE";
}

public class MyClass {
    static {
        // Код статической инициализации
        System.out.println("Статическая инициализация MyClass");
    }

    public MyClass() {
        System.out.println("Конструктор MyClass");
    }
}

public class Start {
    public static void main(String[] args) {
        System.out.println("start");
        new MyClass();
        System.out.println("stop");
    }
}

start
Статическая инициализация MyClass
Конструктор MyClass
stop

SchedulerFactory schedulerFactory = new StdSchedulerFactory();
Scheduler scheduler = schedulerFactory.getScheduler();

public class MyJob implements Job {
  @Override
  public void execute(JobExecutionContext context) {
    System.out.println("Hello, Quartz!");
  }
}

JobDetail jobDetail = JobBuilder.newJob(MyJob.class)
    .withIdentity("myJob")
    .build();

Trigger trigger = TriggerBuilder.newTrigger()
    .withIdentity("myTrigger")
    .startNow()
    .withSchedule(SimpleScheduleBuilder.simpleSchedule()
        .withIntervalInSeconds(10)
        .repeatForever())
    .build();

scheduler.scheduleJob(jobDetail, trigger);
scheduler.start();