Notes for BSc CSIT

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Showing posts with the label Advanced Java Programming

Write a program to read ID, Name, address, salary of twenty employees from keyboard and write in into the file “emp.doc”. Again read records of the employees and display records of those students whose salary is more than 25000.

- February 03, 2022

//Employee.java import java.io.RandomAccessFile; import java.util.Scanner; public class Employee { private int id; private String name; private String address; private double salary; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } public double getSalary() { return salary; } public void setSalary(double salary) { this.salary = salary; } public static void main(String []args) { final int size = 20; int i; Employee e[] = new Employee[size]; Scanner sc = new Scanner(System.in); int id; String n; String a; double s; //setting student objects for(i=0; i<size; i++) { e[i] = new Employee(); System.out.println("Enter id of emp "+(i+1)+":"); id = sc.nextInt(); System.out.println("Enter name:"); n = sc.next(); System.out.pri

How can we access database with servlets?

- January 22, 2022

DATABASE ACCESS WITH SERVLETS Database access with servlets is the same as JDBC. Only the difference is that we have a mysql-connector.jar file in the WEB-INF directory inside our root directory. Example //login.html file <html> <head> <Title> login page </Title> </head> <body> <br><br> <font color=blue size=12> <center> User Authentication page </center></font> <hr color=red size=3> <br><br> <br> <form action="Login" method="post"> <center> <table> <tr> <td> User ID </td> <td> <input type=text name=txtid></td></tr> <tr> <td> Password </td> <td> <input type=password name=txtpass></td></tr> <tr> <td colspan=2 align=center> <input type=submit value=OK> <input type=reset></td></tr> </table> </form> </body> </html> /

Explain getParameterNames() method with example.

- January 22, 2022

Reading Form Parameters Following is the generic example which uses getParameterNames() method of HttpServletRequest to read all the available form parameters. This method returns an Enumeration that contains the parameter names in an unspecified order. Once we have an Enumeration, we can loop down the Enumeration in the standard manner, using has MoreElements() method to determine when to stop and using nextElement() method to get each parameter name. Example //ReadParams.html file <html> <body> <form action="ReadParams" method="POST" target="_blank"> <input type="checkbox" name="maths" checked="checked"/> Maths <input type="checkbox" name="physics" /> Physics <input type="checkbox" name="chemistry" checked="checked" />Chem <input type="submit" value="Select Subject" /> </form> </body> </html> //R

Explain three ways to create the servlets? How can we write servlets program.

- January 22, 2022

Writing Servlets Program There are three ways to create the servlet 1. By implementing the Servlet interface 2. By inheriting the GenericServlet class 3. By inheriting the HttpServlet class 1. Servlet Interface Servlet interface provides common behavior to all the servlets. Servlet interface needs to be implemented for creating any servlet (either directly or indirectly). It provides 3 life cycle methods that are used to initialize the servlet, to service the requests, and to destroy the servlet and 2 non-life cycle methods that are used to get servlet information and servlet configurations. Example import java.io.*; import javax.servlet.*; public class ServletInt implements Servlet { ServletConfig config=null; public void init(ServletConfig config) { this.config=config; System.out.println("servlet is initialized"); } public void service(ServletRequest req, ServletResponse res) throws IOException, ServletException { res.setContentType("text/html"); Printwriter out=