synchronized

public class SynchronizedExample {

  // 동기화된 메소드
  public synchronized void printMessage() {
    System.out.println(Thread.currentThread().getName() + " is running");
  }

  public static void main(String[] args) {
    SynchronizedExample example = new SynchronizedExample();

    // 스레드 생성 및 시작
    new Thread(() -> {
      for (int i = 0; i < 5; i++) {
        example.printMessage();
      }
    }, "Thread-1").start();

    new Thread(() -> {
      for (int i = 0; i < 5; i++) {
        example.printMessage();
      }
    }, "Thread-2").start();
  }
}