The JDK includes the JRE which you can launch by using the java executable in the bin folder. You use this executable just like any other executable.

When you type java in the command line it is actually shorthand. It searches your PATH until it finds the first matching java executable. If you want to specify a different java executable you can give the absolute path to the executable.

C:\Users\Avril> "C:\Program Files\Java\jdk-11.0.1\bin\java" -jar path\to\file.jar

You may be wondering, if you've set JAVA_HOME and PATH to point to JDK-11, why does java -version still use Java 8?

Take a look at your PATH and you'll likely find something like C:\ProgramData\Oracle\Java\javapath as one of the first entries (see this). This entry was added automatically when you installed Java 8 and points to the Java 8 executables (java, javaw, and javaws). Since it's before your %JAVA_HOME%\bin entry, it takes precedence. However, ...\javapath doesn't contain javac and that's why javac -version used JAVA_HOME (Java 11).

The set command only works for the current terminal. To permanently set a system or user environment variable you can use setx.

You can set the variable for the current user like this:

setx JAVA_HOME "C:\Program Files\Java\jdk1.7.0_72"

You can also set the variable system wide (Note: The terminal must be run as administrator fo this) by running the same command with the /m option:

setx JAVA_HOME "C:\Program Files\Java\jdk1.7.0_72" /m

The variable will be available in all new terminal session, but not the current one. If you also want to use the path in the same session, you need to use both set and setx.

You can avoid manipulating the PATH variable if you just once put %JAVA_HOME%\bin in there, instead of the full JDK path. If you change JAVA_HOME, PATH will be point to the new location too.

There are also a few environment variable editors as alternative to the cumbersome Windows environment variable settings. See "Is there a convenient way to edit PATH in Windows 7?" on Super User.

Change your PATH variable so that it has the location of the jdk5/bin directory:

1. Start -> Control Panel -> System -> Advanced
2. Click on Environment Variables, under System Variables, find PATH, and click on it.
3. In the Edit windows, modify PATH by adding the location of your jdk5/bin directory to the beginning. 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 directory as the value.
4. Close the window.
5. Reopen Command prompt window, and run java -version

Here's my guide for Windows 10.

Step 1. Go to System Properties. Click on Environment Variables

Step 2. Add new variables, such as JAVA_8_HOME

• JAVA_8_HOME:%ProgramFiles%\Java\jdk1.8.0_152\bin
• JAVA_9_HOME:%ProgramFiles%\Java\jdk-9.0.1\bin
• JAVA_HOME:%JAVA_8_HOME%

In my case, JAVA_8_HOME(JDK8) is pointing to C:\Program Files\Java\jdk1.8.0_152\bin. You can replace this with your own path to javac. %JAVA_HOME% has a default value pointing to JAVA_8_HOME, which is the path for JDK8. That's my preference, feel free to adjust accordingly.

Step 3. Select PATH and click on Edit. PATH

Step 4. Click on New and add %JAVA_HOME%. %JAVA_HOME% will be added to PATH automatically every time you launch a command prompt.

In order to switch JDK version in cmd, here's the trick. Step 5. I created a batch file with

@echo off
:: Switch JDK version
DOSKEY java8=SET PATH=%JAVA_8_HOME%;%PATH%;
DOSKEY java9=SET PATH=%JAVA_9_HOME%;%PATH%

Basically, it disables echo and creates two alias. In batch file any string after :: is the comments. Every time, java8 or java9 is called, it re-exports %PATH% with the new JDK path. Save it as profile.bat. You can name it whatever you want.

Step 6. Search for regedit (Registry Editor). Click on Edit > New > String Value. Give AutoRun as the Value name and %USERPROFILE%\profile.bat as the Value data. Here, please put your actual path value to the profile.bat we just created. So, whenever a command prompt is opened, it automatically loads profile.bat, which creates those two alias in the script.

Step 7. Close any command prompt you're using or just open a new command prompt. This is because your changes will not affect opened cmd window. Environment changes only happens to new CMD.

Step 8. Verify your results here.

If you're using different Python versions, same trick applies, too. Find my python environment settings here.

java -version is running the wrong version of java.

Diagnostics:

>java -version
java version "1.8.0_66"
Java(TM) SE Runtime Environment (build 1.8.0_66-b18)
Java HotSpot(TM) 64-Bit Server VM (build 25.66-b18, mixed mode)

the following is the Java related contents from the output of PATH:

PATH=C:\ProgramData\Oracle\Java\javapath; ... C:\Program Files\Java\jdk1.6.0_45\bin

Conclusion:

From the above output we can deduce that C:\ProgramData\Oracle\Java\javapath is 1.8.0_66.

You need to change your PATH to put C:\Program Files\Java\jdk1.6.0_45\bin first.

I noticed that after checking the path per your suggestion. Windows 10 does not allow me to edit the path because it says "This environment variable is too large." I know there should be another question to deal with this separately.

You also need to clean up your path. My guess is you have a lot of duplicate entries.