Java Solution

Multiple choice question on java - Part 3

2020-09-04T08:29:00.003-07:00

PART-1 PART-2 PART-3

1 -Using super keyword we can call

sub class constructor
super class constructor
child class object
none of these

2. Data can be passed to the function through

Call by value
call by reference
both of above
none of these

3. Which of the following loop will be execute at least once even if the condition is false

for loop
do-while loop
while loop
none of these

4. Which of the following loop will not execute at least once if the condition is false

for loop
do-while loop
while loop
none of these

5 Inheritance helps in

Reduce redundancy in code
speed up the program
Easy to read
none of these

6. the ++ operator postfix and prefix has the same effect

True
false
Sometime true & sometime false
none of these

7. x=10,y=5 what would be value of z after executing the following statement

if(x>=9&&y<=8)

z=x+y;

else

z=x-y;

15
5
13
none of these

8. Member of the structure are accessed by ----------- operator

address operator
dot operator
scope resolution op
none of these

9. constructor can be overloaded

true
false
in special cases
none of these

10 which of the following is not

the feature of object oriented programming

Data encapsulation
Inheritance
Operator overloading
data structure

Multiple choice question on java - Part -2

2020-09-04T08:14:00.006-07:00

PART-1 PART-2 PART-3

1. The _________ class creates and maintains a buffer for an input stream

Common BufferedInputStream
BufferedStream
InputStream
BufferedInputStream

2.A __________ is a sequence of bytes traveling from a source to a destination over a

communication path.

string
stream
character
integer

3. Which of the following statement is the explanation of the int read () method

Reads a byte of data from the input stream
Reads bytes of data from the input stream and stores them in the array
Reads the number of bytes specified by the third argument from the input stream and

stores.

Returns the number of bytes available for reading from the input stream

4. Which of the following assignments is illegal in Java?

subclass_reference = subclass_object
subclass_reference = superclass_object
superclass_reference = subclass_object
superclass_reference = superclass_object

5. A ___________ is java program that can be embedded in a Web page

Applets
Browser
Package
None of these

6. A applet tag is written in body tag of ___________

HTMM
HTTP
HTML
Applet

7. All applets must be declared as

Protected
Public
Private
Static

8.________ method is called the first time an applet is loaded into the memory

of a computer

init method()
start method()
stop method()
destroy method()

9. Which of the following is a loop construct that will always be executed once?

switch
for
while
do …. While

10. _______ provides a database-programming interface for Java programs

ODBC
JDBC
DBMS
DAT

11. Which of the following is NOT a part of JDBC URL?

<protocol>
<subprotocol>
<subname>
<name>

12. _________package Contains classes that help in connecting to a database

sql.java
mysql.java
java.sql
java.mysql

13. RMI stands for

Remote Method Invocation
Remote method invention
Remote Memory Interface
Reduced Method Instructions

14. CORBA stands for

Common Operation Request Broker Architecture
Common Object Request Bean Architecture
Common Object Request Broker Architecture
Component Object Request Broker Architecture

15. Which of the following statements holds good for JavaBeans?

JavaBeans allows to efficiently constructing applications by Configuring and Connecting Components called Beans.
Java beans are used to transfer data in distributed Systems.
Java Bean is software component architecture of Java designed to use only in one Particular environment
None of the above.

16.Which of the following is not a wrapper class?

Vector
Character
Boolean
Integer

17. Servlets provide an efficient replacement for _______ scripts

18.____________ contains the class libraries that which are needed to create servlets

SDK
JSDK
JDK
JAR

19. Choose the CORRECT statement.

To write JSP code you require a browser.
To test the JSPs you need a server engine.
JSPs looks like HTML script
JSP combines HTML and JDK tools

20. Choose the WRONG Statement

Java is inherently suited for large client/server applications.
A servlet is a small pluggable extension to a server that enhances the server’s functionality
Java does not support networking.
When you use servlet to create dynamic content for a web page or otherwise extend the functionality of a web server.

Java code to find last day of the month

2020-09-03T04:27:00.004-07:00

java 8

import java.time.LocalDate;
import java.time.temporal.TemporalAdjusters;

LocalDate date = LocalDate.now().with(TemporalAdjusters.lastDayOfMonth());

System.out.println("Last day of the month:"+date);

Java code to find first day of the month

2020-09-03T03:58:00.001-07:00

 Calendar cal = Calendar.getInstance();   
 cal.set(Calendar.DAY_OF_MONTH, 1);
 System.out.println("First day of the current month:-"+c.getTime());


Java -8 (using java.time)

LocalDate currentDate = LocalDate.now();

System.out.println("First day of the current month:-" + currentDate.withDayOfMonth(1));

Java code to find duplicate Characters in a String

2020-08-31T20:25:00.002-07:00


import java.util.HashMap;
import java.util.Map;

public class FindDuplicateChar {

    public static void countDuplicate(String str){

        /*Create a Map to store each Character with their count */

        Map<Character, Integer> charMap = new HashMap<Character, Integer>();

        /* Get Character array from String */

        char[] charArray = str.toCharArray();

        /*Iterate over Char Array and populate map*/

        for(Character ch:charArray){

            if(charMap.containsKey(ch)){

                charMap.put(ch, charMap.get(ch)+1);

            } else {

                charMap.put(ch, 1);

            }

        }

        /* Print Character with their count */

        for (Map.Entry entry:charMap.entrySet()) {

            System.out.println(entry.getKey()+" = "+entry.getValue());

        }

    }

    public static void main(String a[]){

        FindDuplicateChar obj = new FindDuplicateChar();

        String text = "ABCDABCDEFGHIJKLABCD";

        System.out.println("Text -"+text);

        FindDuplicateChar.countDuplicate(text);

    }

}

Find no of years in between two given dates

2020-08-23T00:12:00.004-07:00

public static int findYearsInBetween(Date startDate, Date endDate){

   Calendar startCal = getCalendar(startDate);

        Calendar endCal = getCalendar(endDate);

        int diff = endCal.get(Calendar.YEAR) - startCal.get(Calendar.YEAR);

        if (startCal.get(Calendar.MONTH) > endCal.get(Calendar.MONTH) ||

                (startCal.get(Calendar.MONTH) == endCal.get(Calendar.MONTH) 

&& startCal.get(Calendar.DATE) > endCal.get(Calendar.DATE))) {

            diff--;

        }

        return diff;

}

SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yyyy", Locale.ENGLISH);
 
String startDateString = <Give start date here>;

String endDateString = <Give end date here>;
Date startDate = formatter.parse(startDateString);

Date endDate = formatter.parse(endDateString);

System.out.print("No of days :"+ findYearsInBetween(startDate,endDate));

Find number of days between two given dates

2020-08-22T23:44:00.002-07:00

  public static int findDaysInBetween(Date startDate, Date endDate){
        int noOfDays = 0;
        long timeDiff = endDate.getTime() - startDate.getTime();
        long noOfDays = timeDiff / (24 * 60 * 60 * 1000) + 1;
        noOfDays = (int) noOfDays;
        return noOfDays;
    }

SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yyyy", Locale.ENGLISH);
 
String startDateString = <Give start date here>;
String endDateString = <Give end date here>;
Date startDate = formatter.parse(startDateString);
Date endDate = formatter.parse(endDateString);

System.out.print("No of days :"+ findDaysInBetween(startDate,endDate));

Java Code to send mail with attachment

2013-01-18T02:53:00.003-08:00

import java.io.File;
import java.util.Properties;
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.mail.BodyPart;
import javax.mail.Message;
import javax.mail.Multipart;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;

public class Mail {

public static void main(String args[]) {
try{
String host = "smtp.gmail.com";
String from = "shivsriv@gmail.com";
String pass ="Your password";
Properties props = System.getProperties();
props.put("mail.smtp.starttls.enable", "true"); // added this line
props.put("mail.smtp.host", host);
props.put("mail.smtp.user", from);
props.put("mail.smtp.password", pass);
props.put("mail.smtp.port", "587");
props.put("mail.smtp.auth", "true");

String to = "jyotika@gmail.com"; // added this line
System.out.println("preparing mail.....");
Session session = Session.getDefaultInstance(props, null);
MimeMessage message = new MimeMessage(session);

// Get system properties
Properties properties = System.getProperties();

// Setup mail server
properties.setProperty("mail.smtp.host", host);

// Get the default Session object.

// Define message

message.setFrom(new InternetAddress(from));
message.addRecipient(Message.RecipientType.TO,new InternetAddress(to));
message.setSubject("Mail With Attachment");

// Create the message part
BodyPart messageBodyPart = new MimeBodyPart();

// Fill the message
messageBodyPart.setText("Hi this is demo mail with attachment");

Multipart multipart = new MimeMultipart();
multipart.addBodyPart(messageBodyPart);

// Part two is attachment
messageBodyPart = new MimeBodyPart();
File filename = new File("F:/cassandra10.pdf");
DataSource source = new FileDataSource(filename);
messageBodyPart.setDataHandler(new DataHandler(source));
messageBodyPart.setFileName("my.pdf");
multipart.addBodyPart(messageBodyPart);

// Put parts in message
message.setContent(multipart);

// Send the message
Transport transport = session.getTransport("smtp");
transport.connect(host, from, pass);
System.out.println("Mail prepared ....");
transport.sendMessage(message, message.getAllRecipients());
transport.close();
System.out.println("mail Sent ....");
}catch (Exception e) {
System.out.println("Mail failed ....");
e.printStackTrace();
}
}
}

Distinct value in two column

2012-04-21T09:45:00.000-07:00

I have a query in mysql

select f1,f2,f3 from tableName;

I want to remove duplicate value in field f1 and f2 only,

actual query is:

SELECT f1,f2,f3

FROM (SELECT f1,f2,f3 FROM tableName  GROUP BY f1) AS table1 GROUP BY f2;

Send Mail Through Your Gmail Account

2012-02-29T17:49:00.000-08:00

import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.Message.

RecipientType;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import com.sun.mail.smtp.SMTPSSLTransport;

public class SendMailExample {
public static void main(String[] args)throws Exception {

String host = "smtp.gmail.com";
    String from = "sheo.hclcdc@gmail.com";
    String pass ="Your Password";
    Properties props = System.getProperties();
    props.put("mail.smtp.starttls.enable", "true"); // added this line
    props.put("mail.smtp.host", host);
    props.put("mail.smtp.user", from);
    props.put("mail.smtp.password", pass);
    props.put("mail.smtp.port", "587");
    props.put("mail.smtp.auth", "true");

    String[] to = {"shivsriv@gmail.com","triptishukla29@gmail.com"}; // added this line

    Session session = Session.getDefaultInstance(props, null);
    MimeMessage message = new MimeMessage(session);
    message.setFrom(new InternetAddress(from));

    InternetAddress[] toAddress = new InternetAddress[to.length];

    // To get the array of addresses
    for( int i=0; i < to.length; i++ ) { // changed from a while loop
        toAddress[i] = new InternetAddress(to[i]);
    }
    System.out.println(Message.RecipientType.TO);

    for( int i=0; i < toAddress.length; i++) { // changed from a while loop
        message.addRecipient(Message.RecipientType.TO, toAddress[i]);
    }
    message.setSubject("Notification Mail");
    message.setText("Welcome !!!!......This is Automated Mail \nThanks & Regards \n sheo");
    Transport transport = session.getTransport("smtp");
    transport.connect(host, from, pass);
    transport.sendMessage(message, message.getAllRecipients());
    transport.close();
}
}

Netbeans Problem: How To Change Port Number For GlassFish

2012-01-26T08:44:00.000-08:00

Both Oracle an GlassFish runs by default on port number 8080,results in port conflict
Following are simple steps to change the port number of glassfish server :

Go to the folder where Glassfish is installed.
Locate config folder which is as follows: C:\Program Files\glassfish-3.0.1\glassfish\domains\domain1\config
Open domain.xml using any text editor.
Look for 8080 and change it to some other port number that doesn’t conflict with other port numbers.
Save domain.xml.
Now remove GlassFish from NetBeans and add it again so that NetBeans IDE understands the new port number.
Restart GlassFish, if it was already running.

How to change the port number of tomcat

2012-01-26T04:41:00.000-08:00

Default port number of tomcat is 8080, However there is chances of port conflict with others program. Sometime we just need to change the Tomcat port number.
4 simple Steps to change the port number

1.Just search server.xml file in the conf directory [within tomcat installation folder]

2.Search for content like following:

<Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />
    
    <!--
    <Connector executor="tomcatThreadPool"
               port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />

3. change the port attribute to any other port number.

4. save the server.xml file and Restart Tomcat.

what is loadfactor in HashSet and HashMap

2012-01-19T17:07:00.000-08:00

The load factor is a measure of how full the hash set is allowed to get before its capacity is automatically increased. When the number of entries in the hash table exceeds the product of the load factor and the current capacity, the hash table is rehashed (that is, internal data structures are rebuilt) so that the hash table has approximately twice the number of buckets.
If you specify a capacity of 128 and a load factor of .75. The load factor decide when it is time to double the size of the table, in this case, just after you have added 96 elements, not in deciding its initial size.

source:

http://docs.oracle.com/javase/6/docs/api/java/util/HashMap.html

Difference between URL encoding and URL Rewriting

2012-01-18T22:59:00.000-08:00

URL Rewriting is a technique for saving state or session information on the user's browser between page hits. It is a session management technique. The session information gets appended at the end of the URL, as an additional parameter.

Morevoer, if query string parameters are added to the URL, it is important that they
be properly URL encoded. URL encoding refers to the process of encoding special
characters in a string, according to the rules defined in RFC 2396. For example, a
space must be encoded in a URL string as a '+':

http://mypage.com/app/travel?country=Dominican+Republic

Why char[] array is prefere over String to store password in JAVA ?

2012-01-18T09:38:00.001-08:00

Differentiate JVM JRE JDK JIT

2012-01-09T04:44:00.000-08:00

Java Virtual Machine (JVM) is an abstract computing machine. Java Runtime Environment (JRE) is an implementation of the JVM. Java Development Kit (JDK) contains JRE along with various development tools like Java libraries, Java source compilers, Java debuggers, bundling and deployment tools.
JVM becomes an instance of JRE at runtime of a java program. It is widely known as a runtime interpreter.
JIT is the part of the Java Virtual Machine (JVM) that is used to speed up the execution time. JIT compiles parts of the byte code that have similar functionality at the same time, and hence reduces the amount of time needed for compilation.

Infinite while loop in Java

2011-12-20T23:00:00.005-08:00

In The following infinite while loop in Java. It will give compile-time error .

while(true)

{

System.out.println("hello...");

}

System.out.println("End of while"); //Unreachable statement - compiler-error.

The following same infinite while loop, however works and does not gives any errors in which I just replaced the condition with a boolean variable.

boolean v=true;

while(v)

{

System.out.println("hello..");

}

System.out.println("End Of While"); //No error here.

In the second case also, the statement after the loop is obviously unreachable because the boolean variable v is true still the compiler doesn not gives any error. Why?

Ans:

The first Statement always result in an infinite loop because we have specify a constant in condition of while loop, where as in second case compiler assume that, there is possibility of change of value of v inside loop.

DBMS Multiple choice questions

2011-12-20T22:55:00.002-08:00

1. To avoid the problem of updating you can take the following principle for A good database design.

a) Unrelated data should be kept in different table.

b) Table should not contain any redundancy.

c) Table should represent constraint.

d) All the above.

2. The end of SQL command is

a) an end of line character

b) an ‘enter key’ marker

c) an entering F4 key

d) a semicolon(;)

3. In the first normal form -----------------------

a) A composite attributes is converted to individual attributes.

b) Non – key attributes are functional dependent on key attributes.

c) The non – key attributes functionally dependent on not a part of key attributes.

d) All the above.

4. in object oriented software design ‘inheritence’ is a kind of

a) module

b) relationship

c) optimization

d) testing

5. The second normal form are -----------------------

a) A composite attributes is converted to individual attributes.

b) Non – key attributes are functional dependent on key attributes.

c) The non – key attributes functionally dependent on not a part of key attributes.

d) All the above.

6. BCNF required----------------

a) If an attribute of a composite key is dependent on a attribute of other composite key .

b) If a non key attribute dependent on a key attribute.

c) Both a and b.

d) Not a and b.

7. Fourth normal form required---------------

a) When attributes in a relation have multivalued dependencies.

b) If an attribute of a composite key is dependent on a attribute of other composite key.

c) If a non key attribute dependent on a key attribute.

d) None of the above.

8. if a relation has several candidate keys, one is chosen arbitrary to be the -------------key

a) Primary b) alternate

c) Secondary d) none of these

9 Aggregate function in SQL is

a)GREATEST,LIST and ABS

b)SUM,COUNT and AVG

c)UPPER,LOWER and LENGTH

d) none

10. MySQL is based on a tiered architecture consisting of

a) Primary subsystem & support component

b) Mission system & support system

c) Local & global system d) none of these

11. In relational database the column of relation is called-------------

i) attribute ii) relation

iii) Table iv) Entity

12. Which statement are true about the Primary key.

i) It is a candidate key chosen by database to identify tuples in Relation.

ii)It is a set of attributes that form a super key but no proper subset of Which is a super key.

iii)Both I and ii iv)None of the above

13. ----------------integrity ensures that each row can be uniquely identified an attribute called the primary key.

i) Domain integrity ii) Entity integrity

iii) Referential integrity iv) None of the above

14. ------------ is a operator that selects a subset of tuples of the relation.

i) Project ii) Select

iii) Cartesian product iv) None of the above

15. What are the important criteria for designing are-----------

i) Meaningful grouping of attribute

ii) No redundancy

iii) No inapplicable attribute

iv) All the above

16. SQL has following component

i)Data definition language

ii) Data manipulation language

iii) Data control language

v) All the above

17. Which is not a function of aggregate function?

i) Count ii) Avg

iii) Create iv) Max

18. in the natural join the…………..operator is always the equality operator

a) Comparison b) division

c) Multiplication d) none

19. Which SQL query write for find out the list of student with name beginning from s.

i) Select * from student Where name like ‘s—‘

ii) Select * from student where name like ‘s%’

iii) Select name, age from s where name like ‘s%’

iv) None of the above.

20. Which statement is used to add a new column in existing table?

i) Create table abc

( add course varchar(20))

ii) Create table abc

( course varchar(20))

iii) Alter table abc

add course varchar(20))

iv)none

21. Advantage of DBMS is-------------------

a) Controlling redundancy

b) Enforcing Integrity constraints

c)Both a and b d)none

22. RDBMS stands for-------

a) Relational database management system

b) b)Related database management system

c) Relational database managing system

d) None of the above

23. SQL stands for

a) Structured Query language b) System Query language

c) Systematic Query language d) None of the above

24. a relational database stores a minimum of a single -------byte for missing data items in any given row

a) 2 b) “null”

c) 1 d) none

25.Database Management System is a --------

a)Software b)Hardware

c) Both are true

d)None of the above

26. -------------system must be capable of handling thousands of orders placed at the same time

a) OLT P b) Rdbms

c) ISVs d) None of these

27. The command include in DDL is --------

a) Select b) Update

c) Create d) None of the above

28. The command include in DML is --------

a) Grant

b) Update

c) Create

d) None of the above

29. This is not a date type in Sql

a) char b) string

c) Long int d) decimal

30. The ------------------------ command would delete the record from table.

a) Delete b) Drop

c) Remove d) None of the above

If we can use expresion tag instead of putting out.println() into a scriptlet, then why implicit object out is there?

2011-12-20T03:02:00.000-08:00

You might pass the reference of out to other part of web application that does not have direct access to output stream for the response.

How to change the background color of a Frame in swing ?

2011-12-19T03:16:00.000-08:00

JFrame jf=new JFrame(String title);
jf.getContentPane().setBackground(Color.PINK);

Access session In Action class (struts2)

2011-12-16T00:12:00.000-08:00

You can get session on an ActionSupport based Action POJO class as follows:

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class searchAction extends ActionSupport
{
public String execute() throws Exception {

ActionContext ctx= ActionContext.getContext();
   Map m=ctx.getSession();
   m.put("name", "value");

Netbeans Problem: For apache Tomcat server Authentication required dialog box requesting user name and password

2011-12-12T02:20:00.000-08:00

This dialog box appear If a user role and his credentials are not set or is incorrect for Tomcat startup via NetBeans IDE,
OR when user/pass set in IDE is not matches with user/pass in "canf/tomcat-user.xml" file

1..Need to check user name and password set in IDE tools-->server
2..Check \CATALINA_BASE\conf\tomcat-users.xml. whether user and his role is defined or not. If not add these lines
<user username="ide" password="EiWnNlBG" roles="manager-script,admin"/>
</tomcat-users>
3.. set the same user/pass in IDE tools->server
4. restart your server to get effect of changes

Class name for Array in java

2011-12-10T22:12:00.001-08:00

For Java arrays,the class name is '[' followed by an encoded name of the element class. The number of '[' character represent the number of dimension of the array
Element Type Encoding
byte B
boolean Z
char    C
double    D
float       F
int      I
long       J
short    S
class or interface L classname;

for example : for float type array class name is   [F
for int [I
for double a[][]=new double[2][3]
class name id [[D

Sending and Receiving DatagramPacket in java("implementation Of UDP Protocol")

2011-12-09T21:54:00.001-08:00

Sender
import java.net.*;
import java.io.*;

class Sender
{
public static void main(String[] args) throws Exception
{
DatagramSocket ds=new DatagramSocket();
String s=hello!!! this is data"";
byte b[]=s.getBytes();
DatagramPacket dp=new DatagramPacket(b,b.length,InetAddress.getLocalHost(),8);
ds.send(dp);
}
}

Receiver

import java.net.*;
import java.io.*;

class Receiver
{
public static void main(String[] sd) throws Exception
{
DatagramSocket ds=new DatagramSocket(8);
byte b[]=new byte[1024];
DatagramPacket dp=new DatagramPacket(b,b.length,InetAddress.getLocalHost(),8);
ds.receive(dp);
String r=new String(dp.getData());
System.out.println("hi..........");
System.out.println("DATA"+r.trim());
}
}

Socket Programming in java( Simple Chat Program)

2011-12-08T21:39:00.001-08:00

Program For Server
import java.io.*;
import java.net.*;

public class MyServer
{
ServerSocket ss;
Socket s;
DataInputStream din;
DataOutputStream dout;
public MyServer()
{
try{

System.out.println("Server START......");
ss=new ServerSocket(8);
s=ss.accept();
System.out.println("Client Connected.....");
din=new DataInputStream(s.getInputStream());
dout=new DataOutputStream(s.getOutputStream());
chat();
}catch(Exception e){System.out.println(e);}
}

public void chat()throws IOException
{
String str=" ";
do{
str=din.readUTF();
System.out.println("Client Message: "+str);
dout.writeUTF("I have recieved ur message:"+str);
dout.flush();

}while(!str.equals("stop"));

}

public static void main(String arg[])
{
new MyServer();
}

}

Open console and Compile it and run it
C:\java MyServer

Client Program

import java.io.*;
import java.net.*;

public class MyClient
{
Socket s;
DataInputStream din;
DataOutputStream dout;
public MyClient()
{
try{
s=new Socket("127.0.0.1",8);
System.out.println(s);
din=new DataInputStream(s.getInputStream());
dout=new DataOutputStream(s.getOutputStream());
chat();
}catch(Exception e){System.out.println(e);}
}

public void chat()throws IOException
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
String s1;
do{
s1=br.readLine();
dout.writeUTF(s1);
dout.flush();
System.out.println("Server Message: "+din.readUTF());
}while(!s1.equals("stop"));
}

public static void main(String arg[])
{
new MyClient();
}

}

Now open a new console window and compile it an execute as follows

c:\java MyClient
hello
start your chatting now