We are going to learn, what happens while compiling and running the java program. Moreover, we will see some question based on the program.

What happens at compile time?

At compile time, java file is compiled by Java Compiler (It does not interact with OS) and converts the java code into bytecode.

compilation of simple java program 

What happens at Runtime?

At runtime, following steps are performed:

what happens at runtime when simple java program runs

Classloader: is the subsystem of JVM(Java virtual m/c) that is used to load class files.

Bytecode Verifier: checks the code fragments for illegal code that can violate accessright to objects. 

Interpreter: read bytecode stream then execute the instructions.


The path is required to be set for using tools such as javac, java etc.

If you are saving the java source file inside the jdk/bin directory, path is not required to be set because all the tools will be available in the current directory.

But If you are having your java file outside the jdk/bin folder, it is necessary to set path of JDK.

There are 2 ways to set java path:



3. 1) How to set Temporary Path of JDK in Windows

To set the temporary path of JDK, you need to follow following steps:

Open command prompt

copy the path of jdk/bin directory

write in command prompt: set path=copied_path.

IN next post, will come up with permanent method.

  Modified On Feb-21-2018 06:35:37 AM
  1. You can also set path in environmental variables:

    Right click on MyComputer Icon
    Select the Properties from the menu list
    It will open System window 
    Click on Advanced system settings
    Click on Environment Variables, under System Variables, find PATH, and click on it.
    In the Edit windows, modify PATH by adding the location of the class to the value for PATH. If you do not have the item PATH, you may select to add a new variable and add PATH as the name and the location of the class as the value.
    Close the window.

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