IT Knowledge Sharing | Interview questions

Getting real client ip-address using java (if Apache redirection is used...) -------------------------------------------------------------------------- You can use ,     String ipAddress = request.getHeader("X-Forwarded-For");  if you have configured Apache redirection. ------------------------------------------------------------------------- If you will use      request.getRemoteAddr(), it may return 127.0.0.1 if apache redirection has been configured at your deployment server.

Prepared Statement Demo using Java/MySQL ------------------------------------------------ package com.vicwalks.web.util; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import com.mysql.jdbc.Connection; public class PreparedStatementDemo {  public static void main(String[] args) {  System.out.println("===========Prepared statement demo===========\n");  Connection con = null;  PreparedStatement preparedStatement;  try{    Class.forName("com.mysql.jdbc.Driver");    con = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/ DATABASENAME "," userName "," password ");    try{       String sql = "SELECT * FROM employee WHERE salary >= ?";       preparedStatement = con.prepareStatement(sql);       preparedStatement.setInt(1,10000);   ...

Get <td> element value inside a <table> 1) Using JQuery..... $('#tableDivId tr').each(function() {     var tdText = $(this).find("td:first").html();     }); Here you are iterating all rows of a table according to given div id, and then you are fetching first <td> element data for current <tr>.... 2) Without JQuery............... function loadAllTDs(){ var table = document.getElementById('tableDivId');  var rows = table.getElementsByTagName('tr'); var cells, tdText; for (var i = 0, j = rows.length; i < j; ++i) {       cells = rows[i].getElementsByTagName('td');       if (!cells.length) {          continue;       }       tdText = cells[0].innerHTML;  // For 0th td for each tr of this table....       alert(tdText);         } }

com.restfb.exception.FacebookResponseStatusException: Received Facebook error response (code 601): Parser error: SELECT * is not supported.  Please manually list the columns you are interested in. com.restfb.BaseFacebookClient$DefaultLegacyFacebookExceptionMapper.exceptionForTypeAndMessage(BaseFacebookClient.java:147) com.restfb.BaseFacebookClient.throwLegacyFacebookResponseStatusExceptionIfNecessary(BaseFacebookClient.java:208) com.restfb.DefaultFacebookClient.throwFacebookResponseStatusExceptionIfNecessary(DefaultFacebookClient.java:523) com.restfb.DefaultFacebookClient.makeRequestAndProcessResponse(DefaultFacebookClient.java:485) com.restfb.DefaultFacebookClient.makeRequest(DefaultFacebookClient.java:445) com.restfb.DefaultFacebookClient.executeQuery(DefaultFacebookClient.java:366) com.vicwalks.web.util.SocialMediaUtil.findFacebookFriendsUsingRest(SocialMediaUtil.java:84) com.vicwalks.web.action.FacebookConnectAction.execute(FacebookConnectAction.java:87) sun...

If you are using restfb (Facebook graph API and old REST API client wriiten in Java), and you want to access all friend list after Oauth authentication, you can use following method, public List<ArrayList> findFacebookFriendsUsingRest(String facebookAccessToken){   List<ArrayList> myFacebookFriendList= new ArrayList();   final FacebookClient facebookClient;   facebookClient = new DefaultFacebookClient(facebookAccessToken);   User user = facebookClient.fetchObject("me", User.class);   String userName = user.getFirstName();   if (userName == null){   userName = user.getLastName();   }   String userEmail = user.getEmail();   com.restfb.Connection<User> myFriends = facebookClient.fetchConnection("me/friends", User.class);   System.out.println("Count of my friends: " + myFriends.getData().size());   for(User friend: myFriends.getData()){   System.out.println("Friends id and name: "+fri...

For Eclipse users: Please click on Project --> properties-->Resources-->Android--> Select Google api instead of Android Now click on Ok. Check again, Project--> properties--> Java build path , see the Libraries tab, expand Google APIs, and see if there is map.jar and android.jar are available or not. They must be. Now clean your project and then run your project.

Keytool command can be run at your dos command prompt, if JRE has been set in your  classpath variable. For example, if you want to get the MD5 Fingerprint of the SDK Debug Certificate for android, just run the following command... C:\Documents and Settings\user\.android>    keytool -list -alias androiddebugkey                                                                   -keystore debug.keystore -storepass android -keypass android where C:\Documents and Settings\user\.android> is the path which consist the debug.keystore that has to be certified. For detailed information, please visit  http://code.google.com/android/add-ons/google-apis/mapkey.html#getdebugfingerprint

MapActivity is a special sub-class of   android.app.Activity.  If you are using eclipse id, then click on AVD Manager and then it will show you the list of installed as well as un-installed packages. Select Google api packages and click on install. Then you will not this problem. if it is still set  java build path Now if this problem still occurs, see your build path...  http://knowledge-serve.blogspot.com/2011/12/android-mapactivity-can-not-be-resolved.html  

Handling multiple checkboxes with same id's If suppose you have defined more than one checkboxes with sdame id's, then it will treat it as an array of names. <form name="CheckBoxForm"> <input type="Checkbox" name="myCheckbox" id="myCheckbox"  /> <input type="Checkbox" name="myCheckbox" id="myCheckbox"  /> <input type="Checkbox" name="myCheckbox" id="myCheckbox"  /> <input type="Checkbox" name="myCheckbox" id="myCheckbox"  /> <input type="" onclick="testCheckboxes()" /> </form> Now according to HTML, id must be unique. So here it will treat them like an array. So if you want to access them, do as given here, function testCheckboxes(){ var myCheckboxArray= new Array(); var total=document.getElementsByName('myCheckbox').length; for(var i=0;i<total;i++){ ...

Email validation at client side(Java Script) --------------------------------------------- function validateEmailAddress(emailAddress) {      var expression = /^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;     return expression.test(email); } This function will return true if it is a valid email address otherwise false if it is invalid email address. ---------------------------------------------- Email validation at server side using Java ----------------------------------------------- import java.util.regex.Matcher; import java.util.regex.Pattern; public class EmailAddressValidator{  private Pattern pattern;  private Matcher matcher;  private static final String EMAIL_ADDRESS_PATTERN = "^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$";  public Email...

Scrolable DIV: overflow: auto   => It will create a scrollbar - horizontal, vertical or both only if the content in the block                     requires it. overflow: scroll => It will will insert horizontal and vertical scrollbars. They will become active and shown                     only if the content requires it. overflow: visible => It will cause the content of the block to expand outside of it and be visible at the same time. overflow: hidden =>  This forces the block to only show content that fits in the block. Remainng content will                                   be  clipped and not visible to you. There will be no scrollbars. For ex: <div class="scrolableDiv"....></div> where in CSS class: .scrolableDiv{   height:180...

Accessing parent window form from child window in html window.parent.document.parentFormName.submit(); Here parentFormName is the name of Form of parent window that you want to submit from child window. Ex, <form name="parentFormName".....> Accessing parent window's form input parameters to child window, var userName= window.parent.document.getElementById('userName').value; Here userName is the id element of input field on parent form. Ex.     <form name="parentFormName".....> <input type="text" id="userName" /> </form> ---------------------------------------------------------------------------------------------------------------

You can get all contacts exists in your gmail account using this program... First you will need the jar file  gdata  (library files for fetching data from google)... --------------------------------------------------------------------------------- public static  List<ContactDTO> getAllGmailContacts(String gmailId,String password) throws ServiceException, IOException {      InstrumentDTO contactDTO; String name; List<ContactDTO> myGmailContactList= new ArrayList<ContactDTO>(); ContactsService myService = new ContactsService("Find_Contacts_On_Gmail"); myService.setUserCredentials(gmailId, password);     URL feedUrl = new URL(" https://www.google.com/m8/feeds/contacts /"+gmailId+" /full ");         ContactFeed resultFeed = myService.getFeed(feedUrl, ContactFeed.class);           for (int i = 0; i < resultFeed.getEntries().size(); i++) {       ...

Here you can set the alarm using swing, see the code here ------------------------------------------------------------ package example.alarm; import java.awt.*; import java.awt.event.*; import java.text.SimpleDateFormat; import java.util.*; import javax.swing.*; class AlarmDemo extends Thread{ private JLabel timeLabel; public AlarmDemo(JLabel label){    this.timeLabel=label;}         public void run(){       while(true){          Date d=new Date();          int h=d.getHours();          String time="PM";          if (h>23){h-=24; time="AM";}          timeLabel.setText(""+h+":"+d.getMinutes()+":"+d.getSeconds()+"  "+time);          try{Thread.sleep(1000);}  catch(Exception e){}       ...

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You can add a line separator using div .... .line_seperator{        border-left: 2px solid #B1B1B1;     height: 150px;     margin-left: 150px;     margin-top: -35px;     width: 2px; } Here border-left: will add a line.. Even you can use border-right, border-top and border-bottom and then you can arrange your the width of your div.

Here is the example where you can get current time and date using frame in swing import javax.swing.*; import java.awt.*; import java.awt.event.*; import java.text.SimpleDateFormat; import java.util.Calendar; public class DateTimeDemo extends JFrame implements ActionListener{    public static final String DATE_FORMAT_NOW = "dd-MM-yyyy HH:mm:ss";    public static String dt;       JTextField dateField= new JTextField(20);    JButton jb=new JButton("Submit");    public DateTimeDemo() {      super("Current date and time demo");      JLabel label1 = new JLabel(" Your current time: ");                        JPanel contentPane = new JPanel(new FlowLayout());      contentPane.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));      contentPane.add(label1);      conte...

If you are using JQuery and you have created a table and you want to delete it's row dynamically then you can use following code. $(document).ready(function() {     $("# DemoTable  tr").click(function() {             $(this).remove();         }); }); Here  DemoTable is the html Id attribute. So when you will click on the div containing particular row, it will be deleted. For example if you are using table like.. <table id="DemoTable" > <tr>     <td  width="25%"> </td>    <td  width="75%"> </td> </tr> <tr>     <td  width="25%"> </td>    <td  width="75%"> </td> </tr> </table>

import java.io.FileNotFoundException; import java.io.FileOutputStream; import com.itextpdf.text.BadElementException; import com.itextpdf.text.Document; import com.itextpdf.text.DocumentException; import com.itextpdf.text.Element; import com.itextpdf.text.Image; import com.itextpdf.text.PageSize; import com.itextpdf.text.Paragraph; import com.itextpdf.text.Phrase; import com.itextpdf.text.pdf.PdfContentByte; import com.itextpdf.text.pdf.PdfPCell; import com.itextpdf.text.pdf.PdfPTable; import com.itextpdf.text.pdf.PdfWriter; public class GeneratePDFWithImageDemo {   public static void main(String[] args) {          new GeneratePDFWithImageDemo().createPDF();   }   public void createPDF(){  Document document = new Document();       try {         PdfWriter.getInstance(document,          new FileOutputStream("C://Test.pdf"));         docu...

Information-Window: Basic Java Syntax and Rules : Basic Java Syntax If we talk about the Java syntax, Than a basic will cover a Object name referring to an instance with a dot o...

If you want to change the div background then use, document.getElementById("divIdName").style.background='#D6DE26'; Similarly, you can change div's text color dynamically using as  document.getElementById("DivIdName").style.color='#00AEEF';

org.hibernate.PropertyValueException: not-null property references a null or transient value: com.example.server.beans.User.createdOn at org.hibernate.engine.Nullability.checkNullability(Nullability.java:72) at org.hibernate.event.def.DefaultFlushEntityEventListener.scheduleUpdate(DefaultFlushEntityEventListener.java:270) at org.hibernate.event.def.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:128) at org.hibernate.event.def.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:196) at org.hibernate.event.def.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:76) at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:26) at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000) at com.example.persistence.dao.impl.HibernateBaseDAO.saveObject(HibernateBaseDAO.java:88) at com.example.persistence.dao.impl.RegisterUserDAO.saveR...