How Does Static Method Inheritance Differ from Instance Method Inheritance in Java?

Static Method Inheritance in Java

In Java, the inheritance rules outlined in the "A Programmer's Guide to Java™ SCJP Certification" hold true for instance methods. Accessible instance methods are inherited by subclasses. However, the book's explanation fails to consider the unique behavior of static methods in inheritance.

Static methods, as their name implies, belong to the class rather than an instance. They are accessible through the class name, regardless of which subclass is accessing them. This characteristic leads to a deviation from the standard inheritance rules for instance methods.

When a subclass inherits a static method from its superclass, it does not replace or override the method. Instead, the original static method remains accessible within the subclass. This is in contrast to instance methods, where overriding can occur. The reason for this difference is that static methods are associated with the class as a whole, not with individual instances.

In the example code provided, class B can access the display() static method of its superclass, A, using either the simple name display() or the fully qualified name B.display(). Both approaches are valid because the static method is inherited and becomes part of class B's own method set.

It is noteworthy that in the Sun Java Tutorials, it is explicitly stated that subclasses inherit all public and protected members of their parents, including static (class) methods. The distinction between inherited static and non-static methods lies in their behavior when new methods with the same signature are defined in the subclass. While non-static methods can be overridden, static methods are hidden. This means that the new static method in the subclass will take precedence when called from within that subclass, but the original static method remains accessible when called from the superclass.

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