September 2013 ~ ITTechnocrates

27 Sept 2013

The Diffrence between AWT and Swing......

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how to create executable jar file of java...

Step 1: Locate the Jar utility in the JDK folder

Before you do anything else, make sure that you have jdk installed on your computer. You also will need to know the directory to the jdk. Specifically, you will need the path to the Jar utility that is inside your jdk folder. My path to jar is:

· C:\"Program Files"\Java\jdk1.6.0_02\bin\jar

As you can probably tell, I'm using Java 1.6 and within the 'bin' folder is jar which is the program that you will use to make jar files. Basically typing that line up above tells the command prompt that we're going to run the jar utility which is located in the folder C:\"Program Files"\Java\jdk1.6.0_02\bin
On your own computer, the path to the jar utility will probably look similar, it depends on where you installed the jdk to.

Step 2: Create themanifest file

Since you could potentially be compiling many files into one jar file, Java needs to know which one will have the main method. Our example is a bit more trivial since we're just compiling one class into a Jar. Nonetheless, the way that Java knows which of classes has the main method is from a single line in what's known as a manifest file. A manifest file can be a text file made with notepad. I called my manifest file manifest.txt, my manifest file says:

Main-Class: JarDemo

Use the command prompt to navigate to where the JarDemo.class and manifest.txt file are saved and type :

C:\> C:\Path\to\jdk\bin\jar cvfm jarDemoCompiled.jar manifest.txt JarDemo.class
If you don't like always typing out the generally long path to the jdk. You can set the path as follows

c:> path c:\path\to\jdk\bin;%path%

Doing so would allow you to type

C:\> jar cvfm jarDemoCompiled.jar manifest.txt JarDemo.class

When I don't usde the shortcut on my computer, I must type:

C:\> C:\"Program Files"\Java\jdk1.6.0_02\bin\jar cvfm jarDemoCompiled.jar manifest.txt JarDemo.class

cvfm means "create a jar; show verbose output; specify the output jar file name (jarDemoCompiled.jar); specify the manifest file name(manifest.txt) and use the file JarDemo.class to create the jar

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A Look Over Keyboard History and Generation.

Input devices are hardware components that enable users to interact with a computer. Without input devices, we cant feed instructions to a computer. There are lots of possible input devices, but the two most common are a Keyboard and Mouse.

INVENTION OF KEYBOARD

The invention of the modern computer keyboard began with the invention of the Typewriter. Christopher Latham Sholes patente the typewriter that we commonly use today in 1868. The Remington Company mass marketed the first typewriters starting in 1877.

KEYBOARD LAYOUT

The keyboard is one of the most popular ways of inputting information into a computer. It is fast and accurate device. A keyboard layout is the arrangement of the array of key across the keyboard. There are so many different types of keyboard but one keyboard layout is very familiar that layout is “QWERTY”.

QWERTY Keyboard :

Q,W,E,R,T,Y is the first six latters of the top row of the alphabets of the QWERTY layout. The arrangement of QWERTYLayout was given by Sholes, the inventor of the typewriter. Besides the standard alphabet keys having the QWERTY arrangement, computer keyboards also consist of the control keys, the function keys, the numerical keys etc.

PC83-key keyboards:

The PC 83-key was the earliest keyboard offered by IBM with its first Personal Computer.This had 83 keys. The PC/XT keyboard had many of the same features as a standard typewriter at the time, with various changes such as including the 10 function key.

84-key keyboards:

Later IBM added one more key with its PC AT computer keyboard to make it 84-key keyboard in the 1980s. It had 84 keys arranged in three distinct groups, with letters and commonly used keys like the Space bar occupying the center, a set of function keys to the left, and a number pad on the right. The AT keyboard used a round 5-pin connector and an electrical signaling scheme that outlived the keyboards themselves. Today, these types of keyboards are generally only used in aging legacy hardware setups and historical displays.

101-key Keyboard:

In 1986, IBM introduced the IBM PC/AT Model 339. Included in this last AT-family system was the new Enhanced 101-key keyboard. Little did IBM realize at the time, perhaps, but this 101-key keyboard would become the de-facto standard for keyboards for the next decade and beyond. Even today's Windows keyboards and fancy variants with extra buttons and keys are based on this layout.

108-key Keyboard:

A 108-key keyboard that can be connected to any computer with a PS/2 or AT keyboard connector. This is advanced model of the keyboard. This keyboard have more functionality of multimedia key which is designed at the top of keyboard.

The Dvorak Simplified Keyboard:

There are a number of different arrangements of alphabetic, numeric, and punctuation symbols on keys. These different Keyboard Layout arise mainly because different people need easy access to different symbols, either because they are inputting text in different languages, or because they need a specialized layout for mathematics, accounting, Computer Programming or other purpose.

NEW GENERATION KEYBOARD

Foldable Keyboard -

Fold able (also called flexible) keyboards are made of soft plastic or Silicon which can be rolled or folded on itself for travel. When in use, these keyboards can conform to uneven surfaces, and are more resistant to liquids than standard keyboards. These can also be connected to portable devices and smartphones. Some models can be fully immersed in water, making them popular in hospitals and laboratories, as they can be disinfected.

Projection Keyboard -

Projection Keyboards project an image of keys, usually with a laser, onto a flat surface. The device then uses a camera or infrared sensor to "watch" where the user's fingers move, and will count a key as being pressed when it "sees" the user's finger touch the projected image. Projection keyboards can simulate a full size keyboard from a very small projector. Because the "keys" are simply projected images, they cannot be felt when pressed. Users of projected keyboards often experience increased discomfort in their fingertips because of the lack of "give" when typing. A flat, non-reflective surface is also required for the keys to be projected. Most projection keyboards are made for use with PDA and smartphones due to their small form factor.

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Various Mobile Operating Systems:-

There are So many types of Operating Systems available in Mobile Markets. Some are Expensive, Some are Free, Some are Chargeable, and some are Costly. In This Post we take a look and get knowledge of these operating Systems.

Android:-

Symbian

Windows OS

BlackBerry

iOS

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Linux - Install on Windows 7 Virtual Machine using VirtualBox

Microsoft Virtual PC is my choice to run Windows virtual machines. However, installing Linux on Virtual PC is not something I would recommend. Main reason is the lack of integration elements; Virtual PC integration components are designed to run well on XP, Vista and 7 virtual machines. For Linux, Virtual PC does not (at least at this moment) offer any integration components.

VirtualBox integration components are called Guest Additions. They install and run well also in any Linux distro. That's why I recommended creating Linux virtual machines in VirtualBox.

I am using Ubuntu 10.10 to make this tutorial. At the moment it is the most Windows like Linux distro available, a safe bet for a beginner to start experimenting Linux.

For more advanced Linux users I recommend using Novell SUSE 11.3 which is a commercial Linux distribution, free to test, or its free counterpart OpenSUSE 11.3. The setup procedure in VirtualBox is exactly the same.

Microsoft Virtual PC, Oracle VirtualBox and VMware Player are at the moment the best free virtualization applications. All have their pros and cons, I'm not going to put them in any order here. Let's just say I'm using Microsoft Virtual PC for all my XP and Vista virtual machines, and VirtualBox for older Windows and Linux machines.

You can download these virtualization applications here:
Microsoft: Virtual PC
Oracle: VirtualBox
VMware: WMware Player

Part 1: Create a new virtual machine for Ubuntu

Launch VirtualBox
Click New
This opens New Virtual Machine Wizard. Click Next:
Give your new virtual machine a name, choose the right OS and version. These are automatically selected if VirtualBox can determine it from the name you gave. Click Next:
Set the amount of RAM you want to assign to Ubuntu. For running a Linux vm (virtual machine), 512 MB is enough. You can assign as much as you want to, maximum being about 512 MB less of your host computer's RAM. Keep in mind though that RAM used by a running vm is away from the RAM Windows can use; assigning more RAM can make your vm run faster and better but at the same time make your Windows crawl so slowly even the vm halts. My recommendation is always leave at least 2 GB for Windows, or if you have under 4 GB of RAM only give maximum of 1 GB to a vm. Click Next:
.VirtualBox asks now if you want to create a new vhd (virtual hard disk), or use existing vhd. Choose Create new and click Next:
New Virtual Disk Wizard starts. Click Next: .
Click Next to accept Dynamically expanding storage:
Dynamically expanding vhd means that although the guest consideres the HD being the size given (max value), host Windows only uses as much space on HD as is actually needed; a 20 GB dynamic vhd where only 4 GB is used is seen by Windows host as a 4 GB vhd file, not as a 20 GB file, but the guest OS sees the same vhd file as a 20 GB hard disk with 16 GB free. I recommend 8 to 12 GB for Ubuntu.
You can now accept the default location where VirtualBox offers to save the vhd, or change the location by clicking the small folder symbol. Default save folders are Your_Username\.VirtualBox (Virtual Box 3.2 and older) or Your_Username\VirtualBox VMs (from version 4 Beta). You can also change the original size of vhd here. Click Next:
Click Finish to end New Virtual Disk Wizard:
Click Finish to end New Virtual Machine Wizard:
Now choose the virtual machine you just created and click Settings:
Choose Storage from the left pane, CD/DVD from under the title IDE controller, and click the small CD symbol on the right:
Now you need to tell VirtualBox which install media you want to use. You can assign any of the host system's CD/DVD drives to vm , or an ISO image to act as a CD/DVD drive. For now, you want to use the Ubuntu ISO you downloaded earlier. Browse to its location, choose it and click Open:
Now choose Display from the left pane, assign the maximum 128 MB video RAM to virtual machine's emulated video card:
Next you need to setup network controller. Click Network on the left pane, choose Enable Network Adapter, choose Bridged Adapter, and choose your host computer's network adapter from drop down list:
Click OK to save edited settings:

Part 2: Install Ubuntu on a virtual machine

Choose Ubuntu vm, click Start:
When vm starts, it shows you the first screen of Ubuntu setup. Choose the language you want from over 60 languages, or wait 30 seconds for English to be selected:
Ubuntu starts now in so called Live Mode. Double click Install Ubuntu icon:
Once again, choose your installation language:
Choose Download updates while installing. You might also want to install Fluendo MP3 plugin offered for better audio features. Click Forward:
Choose Erase and use the entire disk. Notice please, we are now talking about the virtual hard disk we created earlier, not the actual hd on your host computer. In other words, this does not mean your HD with Windows on it will be erased Click Forward:
Click Install Now:
Choose your time zone:
Choose your preferred keyboard layout. To avoid confusion, I recommend choosing the same you are using on your host computer's Windows. Click Forward:
Tell Ubuntu your name, choose the computer name and set up a password. Click Forward:
Installation starts, you have now some 20+ minutes for a coffee break, or you can watch a presentation about Ubuntu by clicking those arrow symbols on left and right:
When installation is finished, you have to unmount (deattach) Ubuntu ISO image before reboot. Before clicking Restart Now, Open Devices menu from vm window, click CD/DVD devices, choose Unmount CD/DVD Device.
Click Restart Now:
When Ubuntu has booted, click your username to open a password prompt. Type your password, click Log In:
To fully integrate Ubuntu vm to your Windows 7 desktop, to allow networking and for instance cross platform copy & paste, you need to install VirtualBox Guest Additions. Click Devices menu, choose Install Guest Additions:
If the CD/DVD icon appears on the desktop, right click it and choose Open With Autorun Prompt:
If the CD/DVD icon does not appear on desktop (happens sometimes), open Ubuntu's Places menu, and choose VBOXADDITIONS. Choose then Open Autorun Prompt from VBOXADDITIONS window:
Choose Run to start Guest Additions setup:
You must now enter the administrative password. It is the same you chose for your account, so enter it now:
When Guest Additions are set up, you must press Return (Enter) to close the window:
Restart Ubuntu:
After reboot, you are ready to go

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Operating System Subject's IMP Questions..

Operating System Subject's Some Important Questions..

Why is MBR registers required?
Why are interrupts needed? List the limitation of Sequential interrupt processing.
Briefly compare all in board memory.
Define Virtual memory. Briefly explain all levels of system structure.
Define DMA. Briefly explain steps involve in Simple Interrupt Processing.
Explain the key elements of an Operating System for Multiprogramming with figure.
List the objective of time sharing system and multiprogramming system.
Briefly explain Block/Suspend->Block, Ready->Ready/Suspend states of process.
List two events/reasons lead to the termination and suspension of a process?
Why are two modes (user and kernel) needed?
What is the difference between a mode switch and a process switch?
For what types of entities does the OS maintain tables of information for management purposes?
Explain the difference between a monolithic kernel and a microkernel.
Briefly explain SMP with figure. List two advantages and disadvantages of ULTs over KLTs.
What is I/O Management? Write a short note on UNIX SVR4 Process Management.
Define Thread. What resources are typically shared by all of the threads of a process?
Define Process. What do you mean by pure user-level thread? What are the two separate the potentially independent characteristics embodied in the concept of process?
When and how the short-term, medium-term and long-term scheduling policies are applied? Draw the queuing diagram for scheduling.
Explain the resident set management policies for virtual memory. Explain how it affects the degree of multiprogramming.
Define virtual memory. Compare LRU, FIFO and Clock page replacement policies with suitable example.
What is paging? Explain the logical to physical address translation mechanism with example.
What is Monitor? Explain the solution to the Bounded-Buffer
Producer/Consumer Problem using a Monitor.
What is Translation Lookaside Buffer? Explain the Paging with the use of TLB.
What role the main memory cache plays with the Virtual Memory Management using TLB?
Discuss the use of Invert Page Table in paging technique. How physical address is generated in it?
What is deadlock? State necessary conditions for deadlock to occur. Explain
banker’s algorithm for deadlock avoidance.
Define the term. Dispatcher.
What is Process Spawning.
List out three general categories of PCB information.
List out which process states works in virtual memory and which one in primary memory.
Write down the full form of PSW, JCL.
Differentiate between mode switching and process switching.
Define main categories of processor registers and list out the registers in each category.
What is interrupt handler routine?
What is hit ratio?
Explain the issues and resolution for Cash Design.
Explain time sharing system with basic example.
Write short note on Process Control Structures.
Explain process state transition with one and two suspended states.
Compare the Resident set management.
Briefly explain the Address translation in a paging system.