31.OOPS concept in JAVA I

Q1) What is polymorphism? Ans) Polymorphism gives us the ultimate flexibility in extensibility. The abiltiy to define more than one function with the same name is called Polymorphism. In java,c++ there are two type of polymorphism: compile time polymorphism (overloading) and runtime polymorphism (overriding). When you override methods, JVM determines the proper methods to call at the program’s run time, not at the compile time. Overriding occurs when a class method has the same name and signature as a method in parent class. Overloading occurs when several methods have same names with Overloading is determined at the compile time. Different method signature and different number or type of parameters. Same method signature but different number of parameters. Same method signature and same number of parameters but of different type Example of Overloading       int add(int a,int b)      float add(float a,int b)      float add(int a ,float b)      void add(float a)      int add(int a)      void add(int a)                 //error conflict with the method int add(int a) Example: Overloading Class BookDetails{             String title;             String publisher;             float price; setBook(String title){ } setBook(String title, String publisher){ } setBook(String title, String publisher,float price){ } } Example: Overriding class BookDetails{             String title; setBook(String title){ } } class ScienceBook extends BookDetails{             setBook(String title){}                                             //overriding setBook(String title, String publisher,float price){ }  //overloading }

Q2) What is inheritance? Ans) Inheritance is the property which allows a Child class to inherit some properties from its parent class. In Java this is achieved by using extends keyword. Only properties with access modifier public and protected can be accessed in child class. public class Parent{ public String parentName; public int parentage; public String familyName; } public class Child extends Parent{ public String childName; public int childAge; public void printMyName(){ System.out.println(“ My name is “+ chidName+” “ +familyName) } } In above example the child has inherit its family name from the parent class just by inheriting the class.