Monday, November 25, 2013

command for finding the version of weblogic and installed components

1) Go to installed weblogic server lib path
2)Use this command -----java -cp weblogic.jar weblogic.version -verbose
3) you will get like below details. 

============                    ===================
Kernel                          Commonj WorkManager v1.1
TimerService                    Commonj TimerManager v1.1
CorbaService                    CORBA 2.3, IIOP 1.2, RMI-IIOP SFV2, OTS 1.2, CSI
v2 Level 0 + Stateful
XMLService                      XML 1.1
Transaction Service             JTA 1.0.1B
JDBCService                     JSR-114, JDBC 3.0
Servlet Container               Servlet 2.5, JSP 2.1
WebServices                     JSR-173, JAX-RPC, JSR-109, WSDL, WS-Addressing,
WS-Policy, JAX-B, JAX-R, UDDI, WS-Management(HP), JAXP-1.3, WS-Security
Pre Admin Singleton Services S  1.0
Singleton Services Batch Manag  1.0
EJB Container                   EJB 3.0
MDBService                      EJB 3.0
EJBTimerService                 EJB 3.0
J2EE Connector                  1.5
JMS Service                     JMS 1.1

Friday, November 22, 2013

Wednesday, November 20, 2013

spec-version:2.5 version:]] Servlet failed with Exception java.lang.NullPointerException

spec-version:2.5 version:]] Servlet failed with Exception java.lang.NullPointerException

Tuesday, November 5, 2013

A-Z Linux Commands

Command     Description
alias     Create an alias
apropos     Search manual for keyword
at     Schedule a job to run in the future.
awk     Find and Replace text within file(s)
break     Exit from a loop
builtin     Run a shell builtin
bunzip2     Decompress file from bzip2 format
bzip2     Compress file to bzip2 format
cal     Display a calendar
case     Conditionally perform a command
cat     Concatenate files to standard output
cd     Change Directory
cfdisk     Partition table manipulator for Linux
chgrp     Change group ownership
chmod     Change access permissions
chown     Change file owner and group
chroot     Run a command with a different root directory
chvt     Change the virtual Terminal
cksum     Print CRC checksum and byte counts
clear     Clear terminal screen
cmp     Compare two files
comm     Compare two sorted files line by line
command     Run a command – ignoring shell functions
compress     Compress file(s) to old Unix compress format
continue     Resume the next iteration of a loop
convmv     A perl script that converts filenames from one encoding to another
cp     Copy one or more files to another location
cron     Daemon to execute scheduled commands at predefined time
crontab     Schedule a command to run at a later time
csplit     Split a file into context-determined pieces
cut     Divide a file into several parts
date     Display or change the date & time
dc     Desk Calculator
dd     Data Dump – Convert and copy a file
declare     Declare variables and give them attributes
df     Display free disk space
diff     Display the differences between two files
diff3     Show differences among three files
dir     Briefly list directory contents
dircolors     Colour setup for `ls’
dirname     Convert a full pathname to just a path
dirs     Display list of remembered directories
du     Estimate file space usage
echo     Display message on screen
ed     A line-oriented text editor (edlin)
egrep     Search file(s) for lines that match an extended expression
eject     Eject CD-ROM
enable     Enable and disable builtin shell commands
env     Disp, set, or remove environment variables
eval     Evaluate several commands/arguments
exec     Execute a command
exit     Exit the shell
expand     Convert tabs to spaces
export     Set an environment variable
expr     Evaluate expressions
factor     Print prime factors
false     Do nothing, unsuccessfully
fdformat     Low-level format a floppy disk
fdisk     Partition table manipulator for Linux
fgrep     Search file(s) for lines that match a fixed string
file     Determine type of file
find     Search for files that meet a desired criteria
fmt     Reformat paragraph text
fold     Wrap text to fit a specified width.
for     Expand words, and execute commands
format     Format disks or tapes
free     Disp, s memory usage
fsck     Filesystem consistency check and repair.
fstat     List open files
function     Define Function Macros
fuser     Identify process using file
gawk     Find and Replace text within file(s)
getopts     Parse positional parameters
grep     Search file(s) for lines that match a given pattern
groups     Print group names a user is in
gunzip     Decompress file(s) from GNU zip format
gzcat     Show contents of compressed file(s)
gzip     Compress file(s) to GNU zip format
hash     Remember the full pathname of a name argument
head     Output the first part of file(s)
history     Command History
hostname     Print or set system name
iconv     Converts the encoding of characters from one code page encoding scheme to another.
id     Print user and group id’s
if     Conditionally perform a command
import     Capture an X server screen and save the image to file
info     Help info
install     Copy files and set attributes
join     Join lines on a common field
kill     Stop a process from running
less     Display output one screen at a time
let     Perform arithmetic on shell variables
ln     Make links between files
local     Create variables
locate     Find files
logname     Print current login name
logout     Exit a login shell
lpc     Line printer control program
lpr     Off line print
lprint     Print a file
lprintd     Abort a print job
lprintq     List the print queue
lprm     Remove jobs from the print queue
ls     List information about file(s)
ll     #ls -l List information about file(s)
lsof     List open files
m4     Macro processor
makewhatis     Rebuild whatis database
man     Print manual pages
mkdir     Create new folder(s)
mkfifo     Make FIFOs (named pipes)
mknod     Make block or character special files
more     Display output one screen at a time
mount     Mount a file system
mtools     Manipulate MS-DOS files
mv     Move or rename files or directories
netconfig     Configure your network
nice     Set the priority of a command or job
nl     Number lines and write files
nohup     Run a command immune to hangup
od     View binary files
passwd     Modify a user password
paste     Merge lines of files
pathchk     Check file name portability
popd     Restore the previous value of the current directory
pr     Convert text files for printing
printcap     Printer capability database
printenv     Print environment variables
printf     Format and print data
ps     Process status
pushd     Save and then change the current directory
pwd     Print Working Directory
quota     Display disk usage and limits
quotacheck     Scan a file system for disk usage
quotactl     Set disk quotas
pax     Archive file(s)
ram     ram disk device
rcp     Copy files between two machines.
read     read a line from standard input
readonly     Mark variables/functions as readonly
remsync     Synchronize remote files via email
return     Exit a shell function
rm     Remove (delete) files
rmdir     Remove folder(s)
rpm     RPM Package Manager (was RedHat Package Manager)
rsync     Remote file copy (Synchronize file trees)
screen     Terminal window manager
sdiff     Merge two files interactively
sed     Stream Editor
select     Accept keyboard input
seq     Print numeric sequences
set     Manipulate shell variables and functions
shift     Shift positional parameters
shopt     Shell Options
shutdown     Shutdown or restart linux
sleep     Delay for a specified time
sort     Sort text files
source     Run commands from a file `.’
split     Split a file into fixed-size pieces
strings     print the strings of printable characters in (binary) files.
su     Substitute user identity
sum     Print a checksum for a file
symlink     Make a new name for a file
sync     Synchronize data on disk with memory
tac     Print files out in reverse line order
tail     Output the last part of files
tar     Tape ARchiver
tee     Redirect output to multiple files
test     Evaluate a conditional expression
time     Measure Program Resource Use
times     User and system times
timidity     Play midi files and set up software synth to play midi files with other commands.
touch     Change file timestamps
top     List processes running on the system
traceroute     Trace Route to Host
trap     Run a command when a signal is set(bourne)
tr     Translate, squeeze, and/or delete characters
true     Do nothing, successfully
tsort     Topological sort
tty     Print filename of terminal on stdin
type     Describe a command
ulimit     Limit user resources
umask     Users file creation mask
umount     Unmount a filesystem
unalias     Remove an alias
uname     Print system information
unexpand     Convert spaces to tabs
uniq     Uniquify files (remove all duplicate lines)
units     Convert units from one scale to another
unset     Remove variable or function names
unshar     Unpack shell archive scripts
until     Execute commands (until error)
useradd     Create new user account
usermod     Modify user account
users     List users currently logged in
uuencode     Encode a binary file into 7-bit ASCII characters
uudecode     Decode a file created by uuencode
v     Verbosely list directory contents (`ls -l -b’)
vdir     Verbosely list directory contents (`ls -l -b’)
watch     Execute/display a program periodically
whatis     List manual pages by name
wc     Print byte, word, and line counts of a file
whereis     Report all known instances of a command
which     Locate a program file in the user’s path.
while     Execute commands
who     Print all usernames currently logged in
whoami     Print the current user id and name (`id -un’)
xargs     Execute utility, passing constructed argument list(s)
yes     Print a string until interrupted
zcat     Show contents of compressed file(s)
zip     Compress and archive file(s) to zip format
.period     Run commands from a file

Monday, November 4, 2013

How To Answer 10 Common JAVA Questions

1. What does the static keyword mean, and where can it be used?

static can be used in four ways:

    static variables are shared by the entire class, not a specific instance (unlike normal member variables)
    static methods are also shared by the entire class
    static classes are inner classes that aren’t tied to their enclosing classes
    static can be used around a block of code in a class to specify code that runs when the virtual machine is first started up, before instances of the class are created.

2. How do you deal with dependency issues?

This question is purposely ambiguous. It can refer to solving the dependency injection problem (Guice is a standard tool to help). It can also refer to project dependencies — using external, third-party libraries. Tools like Maven and Gradle help manage them. You should consider learning more about Maven as a way to prepare for this question.
3. You want to create a simple class that just has three member variables. Tell me how you’d do this.

This problem seems simple at first, and creating such a simple class is covered in classes like Programming Java for Beginners.

But an experienced programmer will recognize that it’s necessary to know how to correctly override the hashCode() and equals() methods (using, for example, EqualsBuilder and HashCodeBuilder, in the Apache Commons library).
4. What does synchronized do? Tell me how to use it to set a variable just one without any race conditions?

synchronized says that a method has to hold the object’s lock to execute. If used around a block, like synchronized (obj) { ... }, it will grab the lock of obj before executing that block. Classes like Programming Java for Beginners and Java Fundamentals I and II will provide a refresher.
5. What is type erasure?

Type erasure is a JVM phenomenon that means that the runtime has no knowledge of the types of generic objects, like List<Integer> (the runtime sees all List objects as having the same type, List<Object>). The topic of type erasure is covered in Advanced Java Programming.
6. When and why are getters and setters important?

While an advanced Java class covers the topic, the key factor to know for interviews is that setters and getters can be put in interfaces and can hide implementation details, so that you don’t have to make member variables public (which makes your class dangerously brittle).
7. What are the differences between Map, Hashtable, HashMap, TreeMap, ConcurrentHashMap, LinkedHashMap?

    Map is an interface for a key-value map
    HashMap is a Map that uses a hash table for its implementation
    Hashtable is a synchronized version of HashMap
    TreeMap uses a tree to implement a map
    ConcurrentHashMap allows for multiple threads to access it at the same time safely
    LinkedHashMap preserves the iteration order that things were inserted in (others don’t provide a fixed iteration order)

A deeper discussion of the differences can be found in Advanced Java Programming.
8. What are the differences between interfaces, abstract classes, classes, and instances?

    Interfaces are essentially a list of methods that implementations must possess, but have no code or member variables
    Abstract classes cannot be instantiated, but can contain variables, implemented methods, and unimplemented methods
    Classes contain variables and implemented methods only, and can be instantiated
    Instances (or objects) are specific examples of a particular class.

9. If you needed to provide a GUI for your Java program, how would you go about it?

There are a lot of options, from web apps to local applications. Usually, interviewers mean Swing or other GUI toolkits with a question like this. It may be worth going through a course on Java Swing Programming before an interview.
10. How do you test your code?

You should talk about your experience using libraries like JUnit, Mockito, and Selenium. Even if you don’t have extensive knowledge about testing, being able to talk about the libraries is a good first step.

Test-Driven-Development (TDD) is very popular these days, and any experience here would also be good to talk about. There are courses on Test Driven Development in Java which can bring you up to speed.