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java se development kit

Minimum requirement
Minimum requirement:-Very first you have to install jdk software in your machine, automatically JRE will be install in your machine.

In jdk folder you got a another folder name is bin (binary) folder that contains all tools or .exe files like javac,java,appletviewer,……are used for test a application or for execution of program.
In the above installation process all folders comes into one main folder name is java,so java folder contains two folder one is jdk and another is Jre.
Jre folder contains all the required library files in the form of .jar (java archieve file) files.

Requirement on developer machine:-JDK+JRE.

Requirement on client machine:-JRE.

Jdk is used for developed an application.

Jre is used for use (run) an application.

For running a java application we must set path variable, path is environment variable which is used by operating system. Path variable can contains more than one value.
We can set path variable by two ways:-
·           Temporary
·           Permanent


Temporary:-we have to open command prompt and write like this set path= C:\Java\jdk1.8.0\bin
If your java is installed in c drive then we have to set path up to bin folder because all tools are available in bin folder.

Permanent:-first copy C:\Java\jdk1.8.0\bin then right click on my computer then double click onproperties then click on advanced system settings then click on environment variable then select path variable into system variable window  then click on edit button then paste the copied value into variable value text field then click ok button three times .


If your java program is saved in bin folder then no need to set path variable (but not recommended to save here).

First Program Test.java

class Test
{
public static void main(String[]args)
{
System.out.println(“Well-come to javaindore.blogspot.in”);
}

}

for compilation of above program use
javac Test.java

for execution of bytecode use
java Test

Output:-Well-come to javaindore.blogspot.in

In the above program file is saved with the classname.java, here .java is extension of java language. 
we can save java program by any other name(if class is not public) but recommended to save by the class name.

java follows some naming conventions rules(for class ,variables,methods,...),  for class name First letter is capital but for user define class there is no rule but recommended to follow java naming rules for user define class also .

here class is a keyword,used to create a class.

public,static and void are also keyword, here public and static are also known as access modifier.
main is a function, and String[]args is a command line argument,where String is class of java.lang package,[] is a array and args is a arrayname.

In System.out.println(),System is a class of java.lang package,out is a static variable of type PrintStream class declared in side System class and println is method of PrintStream class.


In java language java.lang package is implicitly available for each class ,no need to import explicitly in our program.

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