Super Keyword Javascript

Michael Zippo 04.11.2021

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Super Java: Guide

Inheritance is a key part of object oriented programming that allows a developer to define a new class of an existing class. For example, a class for storing meat suppliers in a health food store could be defined based on a class for storing any product sold in the store.

When working with inheritance in Java, you probably will come across the keyword super. The super keyword is used for access members within a subclass and has a variety of uses in inheriting from superclass members.

This tutorial will discuss the basics with super Java keyword references and examples and how you can use it in your code. By the end of reading this tutorial, you will be familiar with using the super keyword in Java.

Java inheritance

In Java, inheritance is used to define a new class from an existing one. Inheritance is a useful feature because it allows programmers to reduce the amount of code they have to repeat because they can use existing code to create new classes.

Inheritance is used when there is a is-a relationship between two classes. Here are some examples of this kind of relationship:

Meat is food
An iPhone is a phone
A lamp is a piece of furniture li>
a tire is part of a car

by inheriting the code from another method, you can access attributes, constructors and methods stored in this function and the use in your new method is an example of inheritance used Inherit code stored in a BankAccount method to use in a new method called SavingsAccount:

In this example we let’s use the keyword extend to inherit all methods, attributes, and constructors from the BankAccount method and apply them to the new Savin method gsAccount. If you are interested in learning more about Java inheritance, you can read our complete guide on the subject

Java super

The keyword super is used for access members in a subclass. Members of a superclass are constructors, attributes and methods

Java, superclass, also known under the name of the parent class , is the class from which a child class (or subclass) inherits its constructors, methods and attributes. For example, in our previous example, BankAccount was the superclass from which our SavingsAccount inherited its values.

The keyword super is used in three situations, which we will explore below.

Using super for superclass access attributes

In Java, attributes of a superclass and a subclass can have the same name. If you want to explicitly access the contents of a superclass attribute, you must use the keyword super

Here is an example of using super with reference to our example bank account from above to access to a class attribute .:

Our code returns:

in our example, we declared a superclass called BankAccount has an attribute: accountType. accountType is the same as bank account in this class.

We have also defined a subclass called SavingsAccount which inherits its values ‚Äã‚Äãfrom BankAccount. In this subclass, we declare a variable called accountType which stores the type of account held by this class, which in this case is Savings account.

Next, we create a method called printAccountDetails () which, when called, prints the account type of the SavingsAccount, preceded by the Type label account: . We use the accountType variable to print the SavingsAccount account type because the accountType variable has local scope

After it is printed, Parent Account Type: is printed to the console, followed by the AccountType of the BankAccount class. We use super . accountType to refer to the value of accountType which is stored in the parent class’s default constructor.

In our main program, we first create an object of the SavingsAccount method called johnAccount which stores its Account details. We then call the method called printAccountDetails () to retrieve John’s account information.

Using Super to access superclass method

Methods in a subclass and a superclass can have the same name. If you want to access the method stored in a superclass that has the same name as a subclass method, you must use the super keyword.

Here is an example of a super used to access a superclass method, for example using a program that stores bank account information:

Our code returns:

in this example, we declared a superclass called BankAccount has a method: displayAccountType () . When this method is called, Account type:. Bank account is printed on the console

We have also declared a subclass called SavingsAccount which has two methods: displayAccountType () and displayParentAccountType ()

displayAccountType () is executed, Account type:. account of savings is printed on the console. When displayParentAccountType () is executed, we use the super keyword to call displayAccountType () of our parent class. So instead of running the displayAccountType () in the SavingsAccount class, our program runs the

displayAccountType () method in the BankAccount class.

In our main program, we first declare an instance of SavingsAccount called johnSavings. We then call the displayAccountType () method, which executes displayAccountType () of the SavingsAccount method. Finally, we invoke displayParentAccountType () which executes super.displayAccountType () and photo prints Account type:. Bank account on the console

Using super to access superclass constructor

the super keyword is also used to access a constructor of a superclass that shares the same name as the constructor in a subclass. You can learn more about Java constructors in our Java constructor tutorial

To call a superclass constructor from a subclass constructor, we need to use super () in the subclass constructor. Super () must be the first statement in the constructor of the argument.

Here is an example of super () used to call a superclass constructor, using our sample bank account app:

In this example, we have defined a superclass called BankAccount which includes a constructor. This constructor, when called, prints main account type: bank account on the console

We also have defined a sub - class called SavingsAccount which comprises a builder .. It constructor, when called, uses super () to call the BankAccount constructor in the BankAccount class. This printing main account Type: bank account on the console. Then, prints the constructor SavingsAccount main type of account: Savings account at the console

In our main program, we initialize an instance of the SavingsAccount object called johnAccount .. When we initialize johnAccount, SavingsAccount () constructor is executed.

Conclusion

This tutorial discussed, referring to examples, how to use the Java keyword for this purpose . Now, after reading this tutorial, you are ready to start using the super Java keyword like an expert!

We hope this article has helped you to resolve the problem. Apart from Super Keyword Javascript, check other __main__ Python module-related topics.