hiding method in java inheritance

Question

I have two class as following:

public class Car { public static void print() { System.out.println(getWord()); } public static String getWord() { return "CAR"; } } public class BMW extends Car { public static String getWord() { return "BMW"; } } // main method public static void main(String args[]) { BMW.print(); }

After I run above sample, this output is printed:

CAR

My question is: Why is the method getWord() not overriden?

your methods are static, Car.print references Car.getWord — BeyelerStudios
– BeyelerStudios, Commented Sep 29, 2015 at 9:06

Raphael · Accepted Answer · 2015-09-29 09:06:51Z

7

Static methods cannot be overridden because method overriding only occurs in the context of dynamic (i.e. runtime) lookup of methods. Static methods (by their name) are looked up statically (i.e. at compile-time).

answered Sep 29, 2015 at 9:06

Raphael

1,8262 gold badges28 silver badges49 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Tom Over a year ago

OP is talking about "method hiding", not overriding.

Raphael Over a year ago

As tim mentioned below, If you want to hide the print() method, then you can make the method with private access.

Tom Over a year ago

You don't to explain that to me, instead you should add this to your answer so OP can read that. Also don't forget to credit Tims answer if you use parts of his answer in your edit.

Raphael Over a year ago

Now after the update of the question. My answer is good to go :)

Tom Over a year ago

Yes, because someone changed "hiding" to "override" and badly some reviewers don't care about reviewing correctly :(.

Suresh Atta · Accepted Answer · 2015-09-29 09:13:14Z

In Java: fields & static methods do not adhere to dynamic/runtime polymorphism. When you call BMW.print(), it inherits the static definition from Car. Being a static function call it refers to Car.getWord()

Tim Biegeleisen · Accepted Answer · 2015-09-29 09:36:28Z

The getWord() method in class BMW is not called when you call BMW.print() because static methods are associated with a class, not an instance of a class. Once you make the call to the static method BMW.print(), several things are required:

All method calls made from BMW.print() must also be static methods if they are defined inside the BMW class
There is no concept of inheritance, i.e. calling the getWord() method will not propagate to a child class. The reason for this is that getWord() is a static method associated with the Car class itself.

If you really wanted to get your current code to print "BMW", you could try the following (which isn't very good design):

public class Car { public static void print() { System.out.println(BMW.getWord()); } public static String getWord() { return "CAR"; } }

Raghu · Accepted Answer · 2015-09-29 12:12:35Z

According to characteristics of static methods,

we cannot override static methods.
If a method is static and you declare same method in the inherited class with the same as of base class it will not be hidden.

Please check below rules from Java Doc :

Overriding: Overriding in Java simply means that the particular method would be called based on the run time type of the object and not on the compile time type of it (which is the case with overriden static methods)

Hiding: Parent class methods that are static are not part of a child class (although they are accessible), so there is no question of overriding it. Even if you add another static method in a subclass, identical to the one in its parent class, this subclass static method is unique and distinct from the static method in its parent class.

Collectives™ on Stack Overflow

hiding method in java inheritance

4 Answers 4

5 Comments

Comments

Comments

Comments

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

5 Comments

Comments

Comments

Comments

Related