Skip to main content

The Hashtable works like HashMap. Only diffrence is that, all methods are synchronized

package collection.demos;
import java.util.Collection;
import java.util.Hashtable;
import java.util.Map;
import java.util.Set;
public class HashTableDemo {
    public static void main(String[] args) {
        Map<String,Long> phoneNumbers=new Hashtable<String,Long>();
        //Putting values in HashMap
        System.out.println("Values : "+phoneNumbers);
        //getting value for specific key
        System.out.println("Value of key xyz : "+phoneNumbers.get("xyz"));
        //checking for specific key
        System.out.println("There is a value of key xyz "+phoneNumbers.containsKey("xyz"));
        //checking for specific Object
        System.out.println("There is a value 453453344L "+phoneNumbers.containsValue(453453344L));
        //getting collection of values
        Collection<Long> phones=phoneNumbers.values();
        System.out.println("Collection values : "+phones);
        System.out.println("Size of HashMap : "+phoneNumbers.size());
        //Removing the element associated with specified key
        System.out.println("Values after removed : "+phoneNumbers);
        //Getting set of keys
        Set<String> keys=phoneNumbers.keySet();
        System.out.println("Set of Keys : "+keys);
        //Getting entryset of mappings
        Set<Map.Entry<String,Long>> entryset=phoneNumbers.entrySet();
        System.out.println("Entry set : "+entryset);
        //Removing all entries
        System.out.println("Values after cleared : "+phoneNumbers);


Popular posts from this blog

Using HyperSQL (HSQLDB)

HSQLDB is a portable RDBMS implemented in pure java. It can be embedded with your application as well as can be used separately. It is very a small database that supports almost all features of the standard database system. It comes with small jar file that can be found in lib folder. The HSQLDB jar package is located in the /lib directory of the ZIP package and contains several components and programs. Core components of jar file are : HyperSQL RDBMS Engine (HSQLDB), HyperSQL JDBC Driver, Database Manager, and Sql Tool. Installing and Using Download: download latest release of HyperSQL database from website and extract it. You will see following contents. Here "bin" directory contains some batch files those can be used to run a swing based GUI tool. You can use runManagerSwing.bat to connect to database, but database must be on before running it. Directory lib contains File hsqldb.jar . It is the database to be used by you. Running database First

In Process Mode of HSQLDB in web application.

If you want to use the database into your web application, you can use the HSQLDB in In_Process mode. In this mode, you can embed the HSQLDB into your web application and it runs as a part of your web application programm in the same JVM. In this mode, the database does not open any port to connect to the application on the hosing machine and you don't need to configure anything to access it. Database is not expposed to other application and can not be accessed from any dabase tools like dbVisualizer etc. In this mode ,database will be unknown from any other person except you. But in the 1.8.0 version, you can use Server intance for external as well as in process access.  To close the databse, you can issue SHUTDOWN command as an SQL query.   In the in-process mode, database starts from JDBC with the associated databse file provided through  connection URL. for example   DriverManager.getConnection("jdbc:hsqldb:mydatabase","SA","");   Here myd

Write a code for servlet which will display all the fields of Employee table in tabular form.MCS-051,Dec09-3a

import javax.servlet.*; import*; import java.sql.*;   import javax.servlet.http.*;   public class Employee extends HttpServlet   {   public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException,      ServletException   {   res.setContentType("text/Html");   PrintWriter pw = res.getWriter();   try   {   Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");   Connection con=DriverManager.getConnection("jdbc:odbc:dsn");   Statement st=con.createStatement();   ResultSet rs=st.executeQuery("select emp_id,emp_name,emp_dob,mob_no,email from employee");   String tr="";   while({   tr=tr+"<tr>";   tr=tr+"<td>"+rs.getString(1)+"</td>";   tr=tr+"<td>"+rs.getString(2)+"</td>";   tr=tr+"<td>"+rs.getString(3)+"</td>";   tr=tr+"<td>"+rs.getString(4)+"</td>&