Environment Variables

Many operating systems use environment variables to pass configuration information to applications. Like properties in the Java platform, environment variables are key/value pairs, where both the key and the value are strings. The conventions for setting and using environment variables vary between operating systems, and also between command line interpreters. To learn how to pass environment variables to applications on your system, refer to your system documentation.

Querying Environment Variables

On the Java platform, an application uses System.getenv to retrieve environment variable values. Without an argument, getenv returns a read-only instance of java.util.Map , where the map keys are the environment variable names, and the map values are the environment variable values. This is demonstrated in the EnvMap example:

With a String argument, getenv returns the value of the specified variable. If the variable is not defined, getenv returns null . The Env example uses getenv this way to query specific environment variables, specified on the command line:

Passing Environment Variables to New Processes

When a Java application uses a ProcessBuilder object to create a new process, the default set of environment variables passed to the new process is the same set provided to the application’s virtual machine process. The application can change this set using ProcessBuilder.environment .

Platform Dependency Issues

There are many subtle differences between the way environment variables are implemented on different systems. For example, Windows ignores case in environment variable names, while UNIX does not. The way environment variables are used also varies. For example, Windows provides the user name in an environment variable called USERNAME , while UNIX implementations might provide the user name in USER , LOGNAME , or both.

Переменная окружения JAVA_HOME – что это такое и она нужна

Во многих статьях в интернете, документации к инструментам для разработки на Java и в книгах зачастую упоминается JAVA_HOME. Что же такое JAVA_HOME?

Что такое JAVA_HOME

JAVA_HOME это переменная окружения, указывающая на директорию с установленным JDK (Java Development Kit, комплект разработчика Java). JAVA_HOME это соглашение, используемое во многих программах из экосистемы Java.

Какие программы используют JAVA_HOME

• Intellij IDEA, Eclipse, NetBeans
• Apache Maven, Apache Ant, Gradle
• Apache Tomcat
• Jenkins

Некоторые игры, написанные на Java (например, Minecraft), тоже могут требовать установленной переменной JAVA_HOME.

Ошибки, связанные с JAVA_HOME

Если переменная окружения JAVA_HOME не определена, некоторые программы могут выдавать следующие ошибки:

• Переменная среды java_home не определена
• Cannot determine a valid Java Home
• JAVA_HOME is set to an invalid directory
• JAVA_HOME is not defined correctly
• JAVA_HOME environment variable is not set
• JAVA_HOME command not found
• JAVA_HOME not found in your environment
• JAVA_HOME does not point to the JDK

При появлении таких ошибок просто установите переменную JAVA_HOME

Как установить переменную окружения JAVA_HOME в Windows

Сперва вам нужно установить JDK или JRE.

• Установите JDK, если вы занимаетесь разработкой программ на Java
• Установите JRE, если вам нужно только запустить прикладную программу на Java

После установки JDK либо JRE запишите путь установки, он понадобится.

Теперь щёлкните правой кнопкой на «Мой компьютер» → «Свойства» → «Дополнительные параметры системы» → «Переменные среды…». В разделе «Системные переменные» нажмите кнопку «Создать…» и укажите следующие данные:

Имя переменной	JAVA_HOME
Значение переменной	Путь к директории JDK / JRE, например: C:\Java\jdk-11.0.6

Сохраните изменения, кликнув «OK». Теперь выберите в списке переменную окружения Path и нажмите «Изменить…». В конце списка добавьте строчку со значением «%JAVA_HOME%\bin«

Для проверки откройте консоль (Win+R, cmd) и укажите последовательно укажите две команды:

Если вы правильно установили JDK/JRE и правильно установили переменные окружения, вы увидите вывод наподобие этого:

Это будет служить результатом того, что переменная JAVA_HOME установлена правильно и Java работает из командной строки.

Резюме

В данной статье мы рассказали вам, что являет собой переменная окружения JAVA_HOME, где она используется и как её корректно указать.

Setting up enviromental variables in Windows 10 to use java and javac

I got a new laptop with Windows 10 and I want to set it up so I can use java and javac from the command line.

I have searched online but all the guides are for previous versions, and I don’t want to mess around with something I don’t understand.

7 Answers 7

Just set the path variable to JDK bin in environment variables.

But the best practice is to set JAVA_HOME and PATH as follow.

Here are the typical steps to set JAVA_HOME on Windows 10.

1. Search for Advanced System Settings in your windows Search box. Click on Advanced System Settings.
2. Click on Environment variables button: Environment Variables popup will open.
3. Goto system variables session, and click on New button to create new variable (HOME_PATH), then New System Variables popup will open.
4. Give Variable Name: JAVA_HOME, and Variable value : Your Java SDK home path. Ex: C:\Program Files\java\jdk1.8.0_151 Note: It should not include \bin. Then click on OK button.
5. Now you are able to see your JAVA_HOME in system variables list. (If you are not able to, try doing it again.)
6. Select Path (from system variables list) and click on Edit button, A new pop will opens (Edit Environment Variables). It was introduced in windows 10.
7. Click on New button and give %JAVA_HOME%\bin at highlighted field and click Ok button.

You can find complete tutorials on my blog :

Environment variables for java installation

How to set the environment variables for Java in Windows (the classpath)?

14 Answers 14

Java SE Development Kit 8u112 on a 64-bit Windows 7 or Windows 8

Set the following user environment variables (== environment variables of type user variables)

• JAVA_HOME : C:\Program Files\Java\jdk1.8.0_112
• JDK_HOME : %JAVA_HOME%
• JRE_HOME : %JAVA_HOME%\jre
• CLASSPATH : .;%JAVA_HOME%\lib;%JAVA_HOME%\jre\lib
• PATH : your-unique-entries;%JAVA_HOME%\bin (make sure that the longish your-unique-entries does not contain any other references to another Java installation folder.

Note for Windows users on 64-bit systems:

Notice that these environment variables are derived from the «root» environment variable JAVA_HOME . This makes it easy to update your environment variables when updating the JDK. Just point JAVA_HOME to the fresh installation.

Optional recommendations

• Add an user environment variable JAVA_TOOL_OPTIONS with value -Dfile.encoding=»UTF-8″ . This ensures that Java (and tools such as Maven) will run with a Charset.defaultCharset() of UTF-8 (instead of the default Windows-1252 ). This has saved a lot of headaches when wirking with my own code and that of others, which unfortunately often assume the (sane) default encoding UTF-8.
• When JDK is installed, it adds to the system environment variable Path an entry C:\ProgramData\Oracle\Java\javapath; . I anecdotally noticed that the links in that directory didn’t get updated during an JDK installation update. So it’s best to remove C:\ProgramData\Oracle\Java\javapath; from the Path system environment variable in order to have a consistent environment.

In Windows inorder to set

Step 1 : Right Click on MyComputer and click on properties .

Step 2 : Click on Advanced tab

Step 3: Click on Environment Variables

Step 4: Create a new class path for JAVA_HOME

Step 5: Enter the Variable name as JAVA_HOME and the value to your jdk bin path ie c:\Programfiles\Java\jdk-1.6\bin and

NOTE Make sure u start with .; in the Value so that it doesn’t corrupt the other environment variables which is already set.

Step 6 : Follow the Above step and edit the Path in System Variables add the following ;c:\Programfiles\Java\jdk-1.6\bin in the value column.

Step 7 :Your are done setting up your environment variables for your Java , In order to test it go to command prompt and type

who will get a list of help doc

In order make sure whether compiler is setup Type in cmd

who will get a list related to javac

Hope this Helps !

— To set java path —

There are two ways to set java path

A. Temporary

1. Open cmd
2. Write in cmd : javac

If java is not installed, then you will see message:

javac is not recognized as internal or external command, operable program or batch file.

1. Write in cmd : set path=C:\Program Files\Java\jdk1.8.0_121\bin
2. Write in cmd : javac

You can check that path is set if not error has been raised.

It is important to note that these changes are only temporary from programs launched from this cmd.

NOTE: You might have to run the command line as admin

B. Permanent

1. Righ-click on «My computer» and click on properties
2. Click on «Advanced system settings»
3. Click on «Environment variables»
4. Click on new tab of user variable
5. Write path in variable name
6. Copy the path of bin folder
7. Paste the path of the bin folder in the variable value
8. Click OK

The path is now set permanently.

TIP: The tool «Rapid Environment Editor» (freeware) is great for modifying the environment variables and useful in that case

How To Set Java, JRE and JDK Home Path and Environment Variables On Windows?

Java is a very popular programming language which provides a different component in order to run, develop Java applications. JRE or Java Runtime Environment is used to run Java application. JDK or Java Development Kit is used to develop Java applications. In this tutorial, we will learn how to set up Java, JRE, and JDK operating system path variables in order to work properly.

Locate JRE or JDK Path

Before starting the configuration we have to locate the JRE or JDK path. JRE or JDK generally installed on the Program Files or Program Files(x86) directory under the Java directory like below.

Locate JRE or JDK Path

and under the Java directory the JDK is residing.

Locate JRE or JDK Path

Set Java HOME_PATH Environment Variable

Now we have learned the path of the Java, JRE or JDK installation. We can set this path as Java HOME_PATH environment variable. We will open the computer properties with by running sysdm.cpl in the Run menu like below. We can also open it from the File Explorer -> Computer -> Right Click.

Open System Properties

In the system properties, we will navigate to the Advanced tab which provides the Environment Variables button like below.

Open Environment Variables

Below we can see the environment variables menu where we will create the JAVA_HOME system variable and set the path accordingly. We click to the New in order to create a new system variable.

Create New System Variable

Here we will set the Variable Name as JAVA_HOME and the Variable Value the path or Java, JRE or JDK which is C:\Program Files\Java\jdk-12 in this example. Then we will click OK.

Set JAVA Executable Path

If we want to run java.exe or similar executables provided by JRE or JDK we have to add the path of Java in the Path variable like below. We select the system variable named Path and click to the Edit .

Here we click to New which will add a new line to the existing values.

Here we will set the bin folder path which is C:\Program Files\Java\jdk-12\bin in this example.

Add Path System Variable

Then we will click OK and OK in the environment variables screen which will save and activated new path configuration.

Check Java Is Working

We can check the new path configuration simply opening a new command line interface MS-DOS. Then just type java -version which will execute java.exe with the -version option. We can see the current java binary version by running it.

3 thoughts on “How To Set Java, JRE and JDK Home Path and Environment Variables On Windows?”

What is the point in setting the JAVA_HOME to the path to the jdk install folder path if you then edit the Path variable and add the full path to the jdk bin folder? Shouldn’t you make use of the JAVA_HOME variable and add %JAVA_HOME%\bin to the Path instead.

@James Coffey, maybe the point of setting JAVA_HOME is just in preparation for GlassFish:
https://docs.oracle.com/cd/E19182-01/820-7851/inst_cli_jdk_javahome_t/index.html
Still, the author could make use of it in Path as you say, but maybe the author is just trying to keep it simple.

THANK YOU SO MUCH. YOU SAVED MY LIFE. I need to use java in jupyter