Do Interfaces Inherit from the Object Class in Java?

Do interfaces inherit from the Object class in Java?

public class Test {
   public static void main(String[] args) {
       Employee e = null;
       e.equals(null);
   }
}

interface Employee {
}

In Java, interfaces do not inherit from the Object class directly. However, all objects in Java, including instances of interfaces, can access methods from the Object class due to how Java handles objects and types.

class EmployeeImpl implements Employee {
   // Implement necessary methods
}

public class Test {
   public static void main(String[] args) {
       Employee e = new EmployeeImpl(); // Now 'e' is not null
       System.out.println(e.equals(null)); // Calls Object's equals() method
   }
}

Causes

• Java interfaces do not have a superclass hierarchy that includes Object, as they are not classes and thus don't extend any class directly.
• When an interface is implemented by a class, that class is responsible for inheriting from Object, not the interface itself.

Solutions

• To utilize methods from the Object class, you must implement the interface in a class that shares the Object context.
• If you call an Object method on an interface instance (like in the above code), the actual object type being referenced must have implemented the Object methods.

Mistake: Assuming that an interface directly inherits methods from Object.

Solution: Understand that while interfaces don't inherit from Object, concrete implementations do, allowing access to Object's methods.

Mistake: Calling Object class methods on null interface references without proper implementation.

Solution: Always ensure the interface is instantiated with a class that implements it to safely call Object methods.