Java interface objects must always implement which of the following?

In Java, an interface defines a contract that classes must adhere to if they choose to implement that interface. However, it does not require that any particular method or behavior be implemented by the interface itself. Instead, the interface provides a blueprint for what methods the implementing classes should include.

The concept behind an interface is that it allows for multiple classes to define their own version of the behaviors, without locking them in to a specific implementation. This flexibility is one of the key aspects of interface inheritance in Java.

As a result, it is entirely valid for an interface to contain no method signatures at all—meaning it doesn't enforce any specific behaviors on the implementing classes. While classes that implement the interface will have to provide the implementation details, the interface itself does not mandate any behaviors. This foundational aspect of Java interfaces establishes the core advantage of abstraction and polymorphism in object-oriented programming.

Therefore, stating that Java interface objects must implement “no behaviors” reflects the inherent nature of interfaces, which can exist without any defined method implementation.