JAVA-OOPS: POLYMORPHISM

This post covers the topic Polymorphism

POLYMORPHISM

• Poly->many
• Morphism->forms
• Taking more than one forms is called polymorphism or one task completed by many ways

It has 2 types,

1. Method overloading (static binding/compile time polymorphism)
2. Method overriding (dynamic binding/run time polymorphism)

1. Method overloading:

• Class->same
• Method->same
• Argument->differ

• In a same class method name is same and the argument is different is called method overloading
• the argument is depends on
• data types
• data types count
• data type order

Example Program:

public class StudentInfo {

    private void studentId(int num) {

    }

    private void studentId(String name) {     \\ depends on order

    }

    private void studentId(String email, int ph) {     \\depends on data type

    }

    private void studentId(int dob, String add) {     \\depends on datatype count

    }

    public static void main(String[] arg) {

        StudentInfo info = new StudentInfo();

    }

}

• In the same method the argument can't use int and byte because int & byte both are numbers. so it doesn't work.
• public void employeeID(int num, byte num2) is not correct
  

2. Method overriding:

• Class name->differ(using extends)
• Method->same
• Argument->same

• In a different class , the method name should be same and argument name should be same is called overriding

Example Program:

• 1st class(sub class)

public class Boy extends Marriage {

    public void girlName() {

        System.out.println("ramya");

    }

    public static void main(String[] args) {

    Boy.b=new Boy();

    b.girlName();

}

• 2nd class(super class)

public class Marriage {

    public void girlName() {

        System.out.println("priya");

}

output : ramya;

• The same method name in both class it take sub class only
• If we satisfied with super class we go for super class method but we won't satisfy with super class we go for sub class method
• We can assign our sub class to our super class but can't reverse

Example Program:

• Marriage b=new Boy() is possible
• Boy b=new Marriage() impossible
• Inside the class if we use static we don't want to crate object (i.e)

public class Employee{

    public static void addNum(){

        System.out.println("Hello");

    }

    public static void main(String[] args){

    addNum(); // don't want to create object

    }

}

Output: Hello

• If its different class we have to use class name(i.e)

sub class:

public class Employee{

    public static void addNum(){

        system.out.println("Hello");

   }

}

super class:

public class sample{

    public static void main(string[] args){

        Employee.addNum();

    }

}

Output: Hello