Skip to main content

Q) How is polymorphism classified in the implementation point of view?




A)
->polymorphism is divided into 2 types
1)  Static polymorphism
2) Dynamic polymorphism
->if the method name is the same and binding involved is static binding , it is the static polymorphism implementation.
->if method name is the same and binding is dynamic, it is dynamic polymorphism implementation.
->for the dynamic polymorphism implementation the fallowing 3 conditions must be satisfied.

1) Method overriding should be implemented.
2) Super class reference should be referencing the sub class object.
3) The method class is made using super class reference.

->method overloading comes under static binding.

Ex:
class Myservlet
{
   void service (servletRequest req)
    {
       req.getDatafromUser();
    }
}

Here
         Message requesting object is- Myservlet
         Message providing object is - request object
         Message passing is               - getDatafromUser();
->Myservlet object servicing to the User. But it must require user input for that the Myservlet object begging to servletRequest object for input.
->One object needs another object services. That is called inter object communication. That first object send a message (i.e. here getDatafromUser() is the message)


->Myservlet is taking to servletRequest through message passing.

Comments

Popular posts from this blog

Q) Retrieving data from database?

A)   ->to retrieve the data from database we need to submit SELECT statement from JDBC application. -> executeQuery() method of statement object is used for this purpose. This method has the fallowing ResultSet executeQuery(String sql) throws SQLException Ex: ResultSet rs = st.executeQuery(“SELECT * FROM ACCOUNT”); ->objectoriented representation of tables formate data is called ResultSet object. Ao the driver created one object i.e. ResultSet object. ->object orientation representation of a table of records returned from db is nothing but “ ResultSet ” object.  

Q) Explain repeated deletion of records.

A) //RepeatedDeletion.java import java.util.Scanner; import java.sql.*; class RepeatedDeletion {        public static void main(String[] args) {               Connection con= DriverManager. getConnection ( "jdbc:odbc:prince" , "scott" , "tiger" );               PreparedStatement ps=con.PreparedStatement( "DELETE FROM ACCOUNT WHERE ACCNO=?" );               Scanner s= new Scanner(System. in );               while ( true )               {                      System. out .println( "Enter accno : " );      ...

Q) What is JDBC driver? What is its role in java database connection?

A) ->A translation software written in java according o JDBC specification is nothing but “JDBC driver”. -> JDBC driver implements JDBC API. Use single API. JDBC driver role: They are 4 roles   1)       Establishing connection between JDBC client and database server. 2)       Receiving JDBC method calls made by JDBC client while performing database (CRUD) operations. 3)       Translating java method calls into DBMS understandable calls and forwarding them to database server. 4)       Receiving the results from database server. Translating them into java format and handling over the same to the JDBC client.