Notes

java is class based object oriented programming language
java is a hgh level programming language and widely used in distrubted envinorment
java is used in gui,console,web and mobile application
java has three editions:
standard edition(se):comprises of core java libraries as java.lang,java.utl
enterprise edition(ee):comprises of Apis like servelets, jms,jsp,ejb
micro edition(me):used for programming of small products
the main motto :"write once and run anywhere"
java program runs under jvm virtual machine
how java became platofrm independet here bcoz unlike any other programming lang the jav code that runs directly on the jvm itself so here,whether it mac or windows or linux here the codeis nothing to do with os it gets directly worked on the jvm
JRE ;JAVA RUN TIME ENVINORMENT COMPRISES OF JVM AND OTHER LIBRARIES REQUIRED FOR RUNNING A CODE
SO COZ OF THIS HERE WHEN WE WRITE CODE ON UR DEVICE WE CAN JUST GET A CLASS FILE THAT CAN BE RUN ON ANY DEVICE WITH THE HELP OF JRE
first, the code is converted into byte code by compiler and then it is interepeted by java interepter whole code is run under java virtual machine
java has methods and classes:
1.method is a block of code that executes a particular task when ever it is called
2.class is collection of methods which are organized into
* java is a high level interepeted language
* java is simple and robust(eliminates errors)
*java hs features like garbage collecting and exception handling
*java is slower than c and c++ but provides better performance
*java is platform independent; as the code is compiled to byte code it can be run on any platform
as the variable size is fixed in the java language so the size of the code also remains constant irrespective of the platform it is running on
*java supports multithreading so enables us to do multitasking
*java provides oops concept
polymorphism, inheritence ,abstraction,encapulation
version control : the process of accessing and making changes to the source code version control or source control system enable us to makes simeuntnious changes and provide s backup to the data it provides an organized manipulations to the system or source
there are 2 types of version control systems
1.centralized :where the changes are added to the center system :cvs
2.distrubuted systems; where every info is mirrored on the servers or clients instead of centralized system ex: git and merculiar
why choosing distributed over centralized coz it is faster and every machine has a copy of the project they are working or so whenever changes are done it need to be updated on the centralized system so nit reduces the time and there is not neccesarily required that everyone should be connected to server to access and make changes to the system they can make changes and push reposirities and we have lot of backups coz every system carries a copy of the project.
version control; every project file or folder is saved in the format of "file tree", here one change the data and other can work the debugging such that it manages their work doesn't comprise concurrently
benefits are it provides througgh performance and improves the efficiency and agility.
the most popular git server are github.com@free and has a entripise edition called black box
bitbucket works with atalasian products like jira
gitlab has a componenet called runner that enables to diretcly push repositiries buildsup project
So while using the git hub we neeed to register with nusername and password this is called https aunthenication
if it through passhrase then it should be ssh authenication.
git --version decalres the version of thegit bash that is installed
git -- help; shows us the no of help commands
git --config global user.name ""
git --config global user.email
git --config--list
clear