How can it be guaranteed that the Bean will be created with unique characteristics each time it is called?

To ensure that a Bean is created with unique characteristics each time it is called in Java (for example, in Spring), you should use a prototype scope. Unlike singleton, a prototype Bean is created anew with each request.

Example in Spring:

@Component
@Scope("prototype")
public class UniqueBean {
    private final String id = UUID.randomUUID().toString();

    public String getId() {
        return id;
    }
}

Each time it is called from the Spring context, a new instance with a unique id will be created.

If the Bean is created manually or in other frameworks, you can use a factory method or Builder that creates a new object with unique parameters each time.

You can also use the @Lookup method in Spring for dynamic retrieval of a new instance:

@Component
public class Client {

    @Lookup
    public UniqueBean getUniqueBean() {
        // Spring will override this implementation to return a new instance
        return null;
    }

    public void doSomething() {
        UniqueBean bean = getUniqueBean();
        System.out.println(bean.getId());
    }
}

Thus, the key is to use a prototype scope or factories so that each call creates a new object with unique characteristics.