The super keyword is another important one. This is a reference variable that is used to call the immediate parent class. This keyword is expensive when we talk about Inheritance and Polymorphism. There are three uses of the super keyword.
- super with variables
super with constructors with method overridingsuper
Super with variables
- If you use super with instance variables, it will refer to the variables of the immediate parent class.
- Look at the following example.
package com.app.superDemo; public class Parent{ String s = "Parent"; public StringshowMessage ( ){ return s;} }
Child.java
Application.java
package com . app. superDemo ; public class Child extends Parent{ public StringshowMessage ( ){ return super. s;} }
Application.java
package com app . . ; public class Application superDemo { public static void main( String[ ] args){ Child child = new Child( ); System. out. println ( child. showMessage ( ));} }
Super with constructors
- We can use the super keyword to invoke the constructor of the immediate parent class
- Once you instantiate a class, the compiler calls the default constructor of that class.
Parent.java
package com . app. superDemo ; public class Parent{ public Parent( ){ System. out. println ( "Parent");} }
Child.java
package com . app. superDemo ; public class Child extends Parent{ public Child( ){ super( ); System. out. println ( "Child");} }
Application.java
package com . app. superDemo ; public class Application{ public static void main( String[ ] args){ new Child( );} }
Super with method overriding
- If you want to call methods in the parent class, you can use super keyword.
- In overriding, it will call the child class method instead of the parent class.
- Look at the following example.
Parent.java
package com . app. inheritance; public class Parent{ public void ShowMessage( ) { System. out. println ( "Parent");} }
Child.java
package com . app. inheritance; public class Child extends Parent{ public void ShowMessage( ) { super. ShowMessage( ); System. out. println ( "Child");} }
Application.java
package com . app. inheritance; public class Application{ public static void main( String[ ] args){ Child child = new Child( ); child. ShowMessage( );} }
Use of super keyword in Java
Reviewed by Ravi Yasas
on
12:41 PM
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