The Keyword "super"

-
                                               
                                                      The Keyword "super"

Consider we are extending a class from another class using inheritance , we always create an object to a sub class..this is because we can access all super class and sub class  members using sub class object.If super class and sub class members have same name by default only sub class members are accessible.. In this case we can use Super Keyword to access super class member.

 Example1:
      
 Class Mysuper
{
 int i=10;
void show()
{
System.out.println("super class variable:i="+i);
}
}
Class Mysub extends Mysuper
{
int i=20;
void show()
{
System.out.println("sub class variable:i="+i);
}
}
Class TestSuper
{
public static void main(String args[])
Mysub m=new Mysub();
m.show();
}

This will give the  following output:
sub class variable:i=20
So if i want to access the variable i in super class  we can use the Super keyword.

1.super.variable-To access the variable in super class
2.super.method()-To access the method in super class
3.super(variable)-To access super class parameterised constructor
default constructor of the super class is availabe by default in sub class..so no need to call it .
Example2:

Class Mysuper
{
 int i=10;
void show()
{
System.out.println("super class method="+i);
}
}
Class Mysub extends Mysuper
{
int i=20;
void show()
{
super.show();
System.out.println("sub class method="+i);
System.out.pritln("super class variable="+super.i);
}
}
Class TestSuper
{
public static void main(String args[])
Mysub m=new Mysub();
m.show();
}

 Output of this program will be
super class method=10
sup class method =20
super class variable=10







Comments

Post a Comment

Popular posts from this blog

Get rid of boring for loop and try using "range" and "rangeClosed"

-
Most of the Java developer already started using Java 15 but here is the feature in java 8  which  i want  to introduce to the people who doesn't  know about it or may be not using it. Lets see about two static methods  "range()" and "rangeClosed()". Usage  These two methods are available in IntStream and LongStream. IntStream -  IntStream class is an specialization of Stream interface for int primitive. It represents an stream of primitive int-valued elements supporting sequential and parallel aggregate operations.  IntStream is part of the java. util. stream package and implements AutoCloseable and BaseStream interfaces. Syntax range It returns the sequential ordered IntStream .It includes only the startInclusive value . static  IntStream  range( int  startInclusive ,  int  endInclusive) rangeClosed It returns the sequential ordered IntStream .It includes startInclusive and endInclusive values . static IntStream rangeClosed( int startInclusive , int endInclus
Read more

Custom Exception Handling For Spring Boot Rest Controller

-
Image
There can be a scenario where we want to send a custom success or error message as a response to the Rest API call. This can be easily achievable using @ControllerAdvice annotation by implementing Custom Exception Handler. It can be either global error message or controller level messages. Here I am going to explain how to implement a global exception handler in spring boot. Below are the steps to implement custom error response in Spring boot Rest Controller   Implement a custom exception handler by extending ResponseEntityExceptionHandler with @ControllerAdvice annotation. Implement a Custom Exception.  Design a CustomApiException Response Model. Throw custom exception from Rest Service. Step 1 - Implementing a Custom Exception Handler When implementing a custom exception handler either you can implement a custom method to handle the exception or override the default "handleException" method  Example to implement a custom exception handler method  Below exception handler me
Read more

HOW TO USE NOTE PAD AS YOUR PERSONAL DAIRY!!!!!

-
Image
                                                                             HOW TO USE  NOTE PAD AS YOUR PERSONAL DAIRY!!!!! 1. Open a blank Notepad file. 2. Write  .LOG  and not  .log  (case sensitive) as the first line of the file, followed by a enter. Save the file and close it. 3. Double-click the file to open it and notice that Notepad appends the current date and time to the end of the file and place the cursor on the line after. 4. Now type your notes, save and close the file. 5. Now place the cursor on the line after and type your notes. Each time you enter your notes, the time and date gets attached to the notes. Thus your Personal diary is ready to use now !
Read more