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can't install R package due to java error [duplicate]

I went to the Environment Variables in 'System' in the control panel and made two new variables, one for user variables and one for system variables. Both were named JAVA_HOME and both pointing to
C:\Sun\SDK\jdk\bin
But for some reason, I still get the below error when running a Java command...
BUILD FAILED
C:\Users\Derek\Desktop\eclipse\eclipse\glassfish\setup.xml:161: The following error occurred while executing this line:
C:\Users\Derek\Desktop\eclipse\eclipse\glassfish\setup.xml:141: The following error occurred while executing this line:
C:\Users\Derek\Desktop\eclipse\eclipse\glassfish\setup.xml:137: Please set java.home to a JDK installation
Total time: 1 second
C:\Users\Derek\Desktop\eclipse\eclipse\glassfish>lib\ant\bin\ant -f setup.xml
Unable to locate tools.jar. Expected to find it in C:\Program Files\Java\jre6\lib\tools.jar
Buildfile: setup.xml
How can I fix this problem?

Find JDK Installation Directory
First you need to know the installation path for the Java Development Kit.
Open the default installation path for the JDK:
C:\Program Files\Java
There should be a subdirectory like:
C:\Program Files\Java\jdk1.8.0_172
Note: one has only to put the path to the jdk without /bin in the end (as suggested on a lot of places). e.g. C:\Java\jdk1.8.0_172 and NOT C:\Java\jdk1.8.0_172\bin !
Set the JAVA_HOME Variable
Once you have the JDK installation path:
Right-click the My Computer icon on your desktop and select Properties.
Click the Advanced tab, then click the Environment Variables button.
Under System Variables, click New.
Enter the variable name as JAVA_HOME.
Enter the variable value as the installation path for the Java Development Kit.
Click OK.
Click Apply Changes.
Note: You might need to restart Windows
The complete article is here, on my blog: Setting JAVA_HOME Variable in Windows.

What worked for me was adding the %JAVA_HOME%\bin to the Path environment variable with the JAVA_HOME environment variable pointing to the jdk folder.

You have to first Install JDK in your system.
Set Java Home
JAVA_HOME = C:\Program Files\Java\jdk1.7.0 [Location of your JDK Installation Directory]
Once you have the JDK installation path:
Right-click the My Computer icon on
Select Properties.
Click the Advanced system setting tab on left side of your screen
Aadvance Popup is open.
Click on Environment Variables button.
Under System Variables, click New.
Enter the variable name as JAVA_HOME.
Enter the variable value as the installation path for the Java Development Kit.
Click OK.
Click Apply Changes.
Set JAVA Path under system variable
PATH= C:\Program Files\Java\jdk1.7.0; [Append Value with semi-colon]

In cmd (temporarily for that cmd window):
set JAVA_HOME="C:\\....\java\jdk1.x.y_zz"
echo %JAVA_HOME%
set PATH=%PATH%;%JAVA_HOME%\bin
echo %PATH%

You need to set it to C:\Sun\SDK\jdk (Assuming that is where the JDK is installed - It is not the default) - Do not put the \bin in C:\Sun\SDK\jdk\bin.
If your app only runs when you are logged in as the current user then put it in the user variables - If it needs to run for all users on your system then put it in System variables.
You might also need to add %JAVA_HOME%\bin to the path also (Also it depends on whether you run it from just the user or from all users, including System)

http://javahowto.blogspot.com/2006/05/javahome-vs-javahome.html
Control Panel > Java, Java tab, click the View button. In Runtime Parameters, put:
-Djava.home=YOUR_PATH_HERE
Or when you execute Java you can add that command line switch to the command:
java -Djava.home=PATH SomeJavaApp

One Image can fix this issue.
For More

For those who are still stumped with this problem (I tried all the above suggestions) --
If you're on a 64-bit version of Windows and you've installed the 32-bit JDK, besides adjusting PATH variables, you may need to adjust registry variables, too.
I was pulling my hair out, having correctly set my PATH variables -- still to no avail -- and then only finding "vacated" Java entries in my registry, seemingly a deadend of fixing the "misfiring" Java Runtime Environment.
By using Process Monitor to watch the program I was trying to get started, in order to sniff out where it was looking in the registry for Java (Runtime Environment), I triumphantly discovered that it's looking in the 32-bit version of registry entries, found in HKEY_LOCAL_MACHINE\SOFTWARE\**Wow6432Node**\JavaSoft\Java Runtime Environment.
Within that key, you should find subkeys of different Java versions installed (past and/or present). Click on the subkey of the latest version (my subkey is currently 1.7.0_25, for example). After clicking on that subkey, you'll see registry string values listed on the right, and particularly, JavaHome and RuntimeLib. You need to modify the values of those two values to reflect the both the current folder and jvm.dll file, respectively.
For example, in my case, the values were (previously) respectively set at C:\Program Files (x86)\Java\jre7 and C:\Program Files (x86)\Java\jre7\bin\client\jvm.dll which are nonexistent on my machine. I had to update these to the current folder and file of C:\Program Files (x86)\Java\jdk1.7.0_25\jre and C:\Program Files (x86)\Java\jdk1.7.0_25\jre\bin\client\jvm.dll.
Again, this will depend entirely on both what version of Java (JDK and/or JRE) you have installed -- 32 or 64-bit -- and what type of operating system you're on -- 32 or 64-bit. Just know that they're reflected in different locations within the registry (like the Wow6432Node for 32 bit applications, in my case with the 32-bit JDK installed on a 64-bit machine).
Now that I've updated those two registry values, my program runs flawlessly, with no more hiccups or complaints about a missing Java Runtime Environment (stemming from the registry).

This is the official solution for setting the Java environment from www.java.com - here.
There are solutions for Windows 7, Windows Vista, Windows XP, Linux/Solaris and other shells.
Example
Windows 7
Select Computer from the Start menu
Choose System Properties from the context menu
Click Advanced system settings -> Advanced tab
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.
Reopen Command prompt window, and run your Java code.

Windows 7
Go to Control Panel\All Control Panel Items\User Accounts using Explorer (not Internet Explorer!)
or
click on the Start button
click on your picture
Change my environment variables
New...
(if you don't have enough permissions to add it in the System variables section, add it to the User variables section)
Add JAVA_HOME as Variable name and the JDK location as Variable value > OK
Test:
open a new console (cmd)
type set JAVA_HOME
expected output: JAVA_HOME=C:\Program Files\Java\jdk1.8.0_60

We need to make a distinction between the two environment variables that are discussed here interchangeably. One is the JAVA_HOME variable. The other is the Path variable. Any process that references the JAVA_HOME variable is looking for the search path to the JDK, not the JRE. The use of JAVA_HOME variable is not meant for the Java compiler itself. The compiler is aware of its own location. The variable is meant for other software to more easily locate the compiler. This variable is typically used by IDE software in order to compile and build applications from Java source code. By contrast, the Windows CMD interpreter, and many other first and third party software references the Path variable, not the JAVA_HOME variable.
Use case 1: Compiling from CMD
So for instance, if you are not using any IDE software, and you just want to be able to compile from the CMD, independent of your current working directory, then what you want is to set the Path variable correctly. In your case, you don't even need the JAVA_HOME variable. Because CMD is using Path, not JAVA_HOME to locate the Java compiler.
Use case 2: Compiling from IDE
However, if you are using some IDE software, then you have to look at the documentation first of all. It may require JAVA_HOME to be set, but it may also use another variable name for the same purpose. The de-facto standard over the years has been JAVA_HOME, but this may not always be the case.
Use case 3: Compiling from IDE and CMD
If in addition to the IDE software you also want to be able to compile from the CMD, independent of your current working directory, then in addition to the JAVA_HOME variable you may also need to append the JDK search path to the Path variable.
JAVA_HOME vs. Path
If your problem relates to compiling Java, then you want to check the JAVA_HOME variable, and Path (where applicable). If your problem relates to running Java applications, then you want to check your Path variable.
Path variable is used universally across all operating systems. Because it is defined by the system, and because it's the default variable that's used for locating the JRE, there is almost never any problem running Java applications. Especially not on Windows where the software installers usually set everything up for you. But if you are installing manually, the safest thing to do is perhaps to skip the JAVA_HOME variable altogether and just use the Path variable for everything, for both JDK and the JRE. Any recent version of an IDE software should be able to pick that up and use it.
Symlinks
Symbolic links may provide yet another way to reference the JDK search path by piggybacking one of the existing environment variables.
I am not sure about previous versions of Oracle/Sun JDK/JRE releases, but at least the installer for jdk1.8.0_74 appends the search path C:\ProgramData\Oracle\Java\javapath to the Path variable, and it puts it at the beginning of the string value. This directory contains symbolic links to the java.exe, javaw.exe and javaws.exe in the JRE directory.
So at least with the Java 8 JDK, and presumably the Java 8 JRE standalone, no environment variable configuration needs to be done for the JRE. As long as you use the installer package to set it up. There may be differences on your Windows installation however. Note that the Oracle JRE comes bundled with the JDK.
If you ever find that your Java JDK configuration is using the wrong version of the compiler, or it appears to be working by magic, without being explicitly defined so (without casting the spell), then you may have a symlink somewhere in your environment variables. So you may want to check for symlink.

goto Mycomputer(This PC) -> rightclick ->select properties -> Advanced system settings -> environment variables-> in system variables click "New" button and write JAVA_HOME in variable name and path C:\Program Files\Java\jdk1.8.0_131 were jdk is present in variable value-> click ok.
close and reopen the command prompt after setting JAVA_HOME. Sometimes changes does not reflect in the cmd opened before setting the JAVA_HOME.
you can also set JAVA_HOME through terminal itself:
SET JAVA_HOME="C:\Program Files (x86)\Java\jdk1.8.0_131"

In Eclipse: Window->Preferences->Java->Installed JREs
Use the search feature to make sure your latest Java installation is listed; then make sure it is the one that is checked. This should be a JDK not a JRE.

While adding your Java directory to your PATH variable, you might want to put it right at the beginning of it. I've had the problem, that putting the Java directory at the end of the PATH would not work. After checking, I've found java.exe in my Windows\System32 directory and it looks like the first one wins, when there are several files with the same name in your PATH...

Run Eclipse as Administrator.
That solved my problem. I'm still digging for the logic behind it.

if you have not restarted your computer after installing jdk just restart your computer.
if you want to make a portable java and set path before using java, just make a batch file i explained below.
if you want to run this batch file when your computer start just put your batch file shortcut in startup folder. In windows 7 startup folder is "C:\Users\user\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup"
make a batch file like this:
set Java_Home=C:\Program Files\Java\jdk1.8.0_11
set PATH=%PATH%;C:\Program Files\Java\jdk1.8.0_11\bin
note:
java_home and path are variables. you can make any variable as you wish.
for example set amir=good_boy and you can see amir by %amir% or you can see java_home by %java_home%

After hours of work around most of the solutions here, the problem was solved for me just by installing 32-bit JDK.

You may wanna look into Windows/System32 folder for the following files:
- java.exe
- javaw.exe
- javaws.exe
Because, the path variable is including these files, you can get a headache trying to figure out why the java -version or javac -version keeps pointing to the old JAVA_HOME: rename those files, take out the extension with an underscore, for instance. And then, you only will have to create the JAVA_HOME variable, add it to the path variable (e.g., %JAVA_HOME%) and append the "\bin" particle. This way you need to only change the JAVA_HOME variable pointing to different JRE or JDK and have multiple installations of java just by setting JAVA_HOME.
This also means that it is better to install Java manually, without an installer, so you are able to toy with it.

Java -version shows java 8 while java 11 is installed

After installing java 11 on my system, runtime continues to be 1.8
Versions of java installed:
C:\Program Files\Java\jre1.8.0_201
C:\Program Files\Java\jdk-11.0.3
JAVA_HOME env variable value: C:\Program Files\Java\jdk-11.0.3
From command prompt running java -version command, expecting to see java 11 info but instead I see java 8.
Changing environment variable value does not change the results, rebooting doesn't seem to be doing anything.
C:\Users\user>java -version
java version "1.8.0_211"
Java(TM) SE Runtime Environment (build 1.8.0_211-b12)
Java HotSpot(TM) Client VM (build 25.211-b12, mixed mode)
expected is that java 11 runtime info is displayed

This just happened to me yesterday. Followed instructions to the letter, and still resulted in a different Java version (1.8.0) instead of the expected (11.0.5) for my downloaded version of JDK11. Funny enough, CMD prompt returned the correct Java version (11.0.5) for the 'javac -version' command, but not for the regular 'java -version' command. I was even told to try uninstalling the existing Java load by my IT expert, as he couldn't think of anything else to try... (I did not end up removing Java)
Turns out he did help me though, perhaps accidentally, but only realized this in hindsight. He told me to try moving the path variable
%JAVA_HOME%\bin
up to the very top of the displayed list of path variables found within the [Edit environment variable] window, for the PATH System Variable option. This did not work immediately, so we figured it had no effect. But I believe this failed because it turns out I had made an oversight when typing the variable in the first place. I had written the word "home" using small caps, instead of large caps. Once I realized my mistake and fixed it to show "HOME" in large caps, my CMD prompt returned the correct java -version of (11.0.5), which matched the javac -version command result.
Please note:
I then tried moving the %JAVA_HOME%\bin variable back to the bottom of the list, where it was originally created, and the java -version command no longer displayed v.11.0.5, but returned the original answer of v.1.8.0. So, I played around a bit and found that this variable needs to be ABOVE the following variable within the existing PATH window:
C:\Program Files (x86)\Common Files\Oracle\Java\javapath
Hope this helps others as it helped me!

In the Environment Variables move the JAVA_HOME above like the picture under:
And for Java 8 you can create JAVA8_HOME as in the picture

In system environment variables, append PATH to point to new JDK's bin folder, and remove the old entry
%JAVA_HOME%\bin

I solved this by updating the path in user variables instead of updating in system variables.
Currently I have:
JAVA_HOME = C:\Program Files\Java\jdk-11.0.6
and
path containing %JAVA_HOME%\bin
(in User variable)

I happened to encounter the same issue and this is how I had resolved it.
In cmd/terminal - type where java, this will return all installed versions of java in the system.
In my case, I had installed java 11 somehow some time ago (which I don't remember when). I then deleted the 2 directories of java 11 and Oracle java in the above list carefully. Then Added the JAVA_HOME
and PATH - %JAVA_HOME%\bin accordingly, then it worked.

1: Click on Start (Windows) button.
2: Write Environmental variables.
3: Select the item.
4: Go to Advanced tab.
5: Click Environmental Variables.
6: Look for the one called "path".
7: Check for the java 7 instalation and change it to the path of your Java 11 instalation (C:\Program Files\Java\jdk-11.0.3).

Just make sure that you have added the following path in both user variables and system variable .
C:\Program Files\Java\jdk-11.0.3
it will definitely work , if not try placing them at the top.

On Windows 10
Download JDK 11, run the .exe .
Follow the steps and the problem will be solved!
Copied the link where the jdk is stored.
e.g. :C:\Program Files (x86)\Java\jdk-11.0.12\ bin
System Properties -> Environment Variables -> (in System variables section) -> click the Path -> Edit -> in the path list (C:\Program Files (x86)\Common
Files\Oracle\Java\javapath), click next to it, the Edit text(click ok), now copy the path where the jdk is stored at the end of the path list .
On the same section(in System variables section) -> click New -> variable name : JAVA_HOME and Variable Value : C:\Program Files (x86)\Java\ jdk-11.0.12 (without file bin!!) -> click ok and close the windows.
Open CMD and run -> java - version and next javac -version.
I hope you found it useful.

Java 9: java.dll not found [duplicate]

why do I get this? How can I fix it?
C:\Users\ash>java version
Error: Registry key 'Software\JavaSoft\Java Runtime Environment'\CurrentVersion'
has value '1.7.0_01', but '1.7' is required.
Error: could not find java.dll
Error: Could not find Java SE Runtime Environment.

The accepted solution for Reinstalling ALL JDKs was a bit harsh.
I too experienced this problem and here is my 2 cents:
This problem started happening since I installed JDK 8 and still had JDK 6 installed. I need for different projects I'm working on.
I noticed I had both a User and a System %JAVA_HOME%, so I removed my User %JAVA_HOME% variable and left only the system one.
I also noticed that in my Oracle installation there was some Java executables and I believe those where the ones conflicting since both my Oracle and Java installations were in my %PATH% variable.
I removed all Java paths from my %PATH% Variable and only left the %JAVA_HOME%\bin at the start of the variable for avoiding any conflicts with the Oracle installation.

I had a similar issue after installing the java 1.8.
To fix this go to Advance System setting --> path and remove
C:\ProgramData\Oracle\Java\javapath;

Removing
C:\ProgramData\Oracle\Java\javapath;
work like charm

Reinstall JDK and set system variable JAVA_HOME on your JDK. (e.g. C:\tools\jdk7)
And add JAVA_HOME variable to your PATH system variable
Type in command line
echo %JAVA_HOME%
and
java -version
To verify whether your installation was done successfully.

I had a similar issue after installing the java 10.0
To fix this go to Advance System setting --> path and remove
C:\ProgramData\Oracle\Java\javapath;

I had to remove the Common Files javapath from the 'Path' that was conflicting, in order to make it work. Now thankfully the java -version works just fine.
C:\Program Files (x86)\Common Files\Oracle\Java\javapath

Make sure your JDK Path variable is directing to the \bin folder and is at the top of the list, because it always uses the first match. By moving it to the top you can make sure that no other path is matched first.
If there's any other entry that has a file called java (such as C:\ProgramData\Oracle\Java\javapath) it will run the command against that file instead of the java file in your JDK. There's no need to reinstall the entire JDK unless your files are corrupt or damaged for some reason.

This problem generally occurs in Windows when your "Java Runtime Environment" registry entry is missing or mismatched with the installed JDK. The mismatch can be due to multiple JDKs.
Steps to resolve:
Open the Run window:
Press windows+R
Open registry window:
Type regedit and enter.
Go to: \HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\
If Java Runtime Environment is not present inside JavaSoft, then create a new Key and give the name Java Runtime Environment.
For Java Runtime Environment create "CurrentVersion" String Key and give appropriate version as value:
Create a new subkey of 1.8.
For 1.8 create a String Key with name JavaHome with the value of JRE home:
Ref: https://mybindirectory.blogspot.com/2019/05/error-could-not-find-javadll.html

I edited my path to put the Oracle JDK at the start of the path and that fixed it.

Problem:
We had the same problem in our Windows 2012 server. We used JAVA_HOME environmental system variable, an we used in the PATH this kind of settings: ...%JAVA_HOME%/bin;...
and no other java related settings was in the PATH.
The problem was we had a space at the end of the value of the JAVA_HOME variable. Like 'C:\Program Files\Java\Jdk 1.8.0_172 ' so the %JAVA_HOME%/bin meant 'C:\Program Files\Java\Jdk 1.8.0_172 \bin'. So because the value was split by space and the system tried to find java.exe at 'C:\Program Files\Java\Jdk 1.8.0_172' where it is obviously not.
Solution was: Delete the space from the end of value of the JAVA_HOME !

Uninstall Java from machine
Check Java folder is deleted from Program Files
Check Registry does not have any instance of Java
Open system Variables and delete the ONLY java path from PATH
Now install the new version again.
Set the Path in System Variables.
This process cleans up all the traces of java and then install fresh java.
Note: This issues occurs when there is multiple installation and uninstall done.

You could be using a 32 bit version of java on a 64 bit environment.
Export the registry hive form HKLM\Software\JavaSoft and import into HKLM\Software\Wow6432Node\JavaSoft. For 1.6 I only needed JavaHome and RuntimeLib values.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Javasoft]
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Javasoft\Java Runtime Environment]
"CurrentVersion"="1.6"
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Javasoft\Java Runtime Environment\1.6]
"JavaHome"="C:\\Java\\jre"
"RuntimeLib"="C:\\Java\\jre\\bin\\client\\jvm.dll"

None of the above worked for me, unfortunately.
The error solved when I uninstalled the old JDK versions that were installed on my computer. I did it simply with the "Uninstall or change a program" tool (under the Control Panel).

I removed the "C:\Program Files (x86)\Heroku\bin" from PATH variable and the problem has gone. I think it is probably the Heroku require different version of Java. So check all directories in your PATH variable, remove the possible ones may have confliction.

If you face this error in cmd with another error as "could not find runtime environment" after you have done all settings in Environment Variable. Then you just need to run jre.exe in your jdk folder and reinstall it and then recheck it by java -version command. Hope it will help you.

rename file "C:\Windows\System32\java.exe" to "C:\Windows\System32\java_old.exe"
CMD --> java -version
done.

In my case the regedit information was correct and the problem was solved by doing the below:
1) setting JAVA_HOME to jdk - set JAVA_HOME=C:\Program Files\Java\\bin
2) setting PATH to jre - set PATH="C:\Program Files\Java\\bin"

after adding the requirements path as illustrated up and deleting C:\ProgramData\Oracle\Java\javapath;. don't forget to reopen your editor.

Go to CMD and type the following:
SET PATH=C:\Program Files\Java\jdk1.8.0_291\bin
(here jdk1.8.0_291 represents your java version, it may differ for you)

java -version and javac -version showing different versions

I have java 7 and java 8 both installed on my windows system under C:\Program Files\Java
In the environment's path I specified the path of java 7 like this.
%JAVA_HOME%/bin where JAVA_HOME = C:\Program Files\Java\jdk1.7.0_17
But when I type javac -version it shows javac 1.7.0_17 which makes sense
but when I do java -version it shows
java version "1.8.0"
Java(TM) SE Runtime Environment (build 1.8.0-b132)
Java HotSpot(TM) 64-Bit Server VM (build 25.0-b70, mixed mode)
Any idea what may be the problem here?
Edit The installed folder :
And one more thing echo %PATH% has only one occurence of JDK that is for java 7 and no occurence for JRE found in it.

The issue is occuring most probably because you have a JRE in your PATH, before your JDK. This usually happens when we add JDK in the PATH and do not remove previously added JREs. Thus when you do java it points to the JRE and when you do javac it points to the other version/JDK (since the JRE does not have a javac in it)
If you don't have any JREs in your path, then you can copy your %JAVA_HOME% and paste it first in your path variable (make sure its before the system32 path).
A possible reason for why this works is explained in this answer:
JRE also puts a java.exe to c:\Windows\System32, that's how first command is resolved. Second command is resolved by the C:\Program Files\Java\jdk1.7.0_02\bin entry in your PATH variable.
If (and when) you are developing from the command prompt, you have to adjust the PATH variable so that C:\Program Files\Java\jdk1.7.0_02\bin is before c:\Windows\System32.

Go to Environment Variables in your windows machine.
In User Variables : Make sure to set
- Your user variable "JAVA_HOME" value to "C:\Program Files\Java\jdk-xxxx\bin"
where "jdk-xxx" is the version of your jdk.
In System Variable :
- Add same "C:\Program Files\Java\jdk-xxxx\bin" value to "Path" variable.
make sure to move the added value on top of all values.
Now try running java -version and javac -version.
worked for me. :) Here i've linked my screenshot

Ok, as you said that you have no JRE on your path, I assume that where java (if you have Windows 7) will give you C:\Windows\System32\java.exe.
Changing the java running
Try using the Java-Settings Dialog from the control panel to change the Java System Version, which is currently active. This should change the version java -version is returning. If this does not work, you will probably need to reinstall the Java version of which you want to run the java command, specify the path explicitly, write you own wrapper (which works if you are in the same directory as the wrapper) or place the JRE path before C:\Windows\System32\ onto your path (don't know if last option really is a good one).
A wrapper could look just like this:
#"C:\Program Files\Java\jre7\bin\java.exe" %*
and you can either name it java.bat (where it will work if you are in the same directory or put it in PATH before C:\Windows\System32\java.exe or you could name it java7.bat and put it anywhere on you path to be able to run the Java 7 JRE if you desire to do so.
A wrapper is also a good option if you want to change the JAVA_HOME when running.
Changing the javac running
If you want to run a different javac hit Windows + Pause and open the system dialog to change the PATH so it contains the path to your JDK 8 instead of your JDK 7. You will need to restart your command line for changes to show.

It's all about $JAVA_HOME system variable
In my case
for Windows
(moving jdk8 -> jdk9 -> jdk11) I had a garbage
left by jdk8 in PATH (before JAVA_HOME:"C:\path\java11")
so I just remove C:\ProgramData\Oracle\Java\javapath_jdk8 from system variables
// or place it below javapath_jdk11
for MAC edit .zshrc to have
export JAVA_HOME="/Library/Java/JavaVirtualMachines/jdk-???.jdk/Contents/Home"

To resolve such kind of environment issue I always believe on command whereis,
To do the same in windows download whereis.exe then set in path and execute the command
whereis java.exe
whereis javac.exe
You will easily find the exact path from which location java is being called in environment as well about javac.

Please check that you have replaced "C:\ProgramData\Oracle\Java\javapath;" with %JAVA_HOME%/bin in the PATH variable. This did the trick for me.

FOR LINUX USERS
if java and javac are showing different versions, then you can easily set them to the correct or same versions
step 1
sudo update-alternatives --config java
output :
Selection Path Priority Status
------------------------------------------------------------
0 /usr/lib/jvm/java-11-openjdk-amd64/bin/javac 1111 auto mode
1 /usr/lib/jvm/java-11-openjdk-amd64/bin/javac 1111 manual mode
* 2 /usr/lib/jvm/java-8-openjdk-amd64/bin/javac 1081 manual mode
this will show the following results, start(*) indicates the javac version that your system is using. You can change it by selecting your required version.
step 2
sudo update-alternatives --config java
output :
Selection Path Priority Status
------------------------------------------------------------
0 /usr/lib/jvm/java-11-openjdk-amd64/bin/java 1111 auto mode
1 /usr/lib/jvm/java-11-openjdk-amd64/bin/java 1111 manual mode
* 2 /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java 1081 manual mode
Now again you can select the version you want to run for java.
This way you can ensure that java and javac are having the same versions.

A side note with the accepted answer. I couldn't leave the trail of java-1.8.0, but I have installed java 17 and want java "17", so, I placed java 17 bin path in the first place (top most ) of path variables, Home variable and user variable, after that when I type in cmd : java -version, it also show java-1.8.0, then I restart cmd, restart Intellij ide, then I type java -version, then it shows :
java version "17" 2021-09-14 LTS
Java(TM) SE Runtime Environment (build 17+35-LTS-2724)
Java HotSpot(TM) 64-Bit Server VM (build 17+35-LTS-2724, mixed mode, sharing)
and when I type :
C:\Users\dell>javac -version
It shows :
javac 17
Here is My path variables ScreenShots and command window :

Yes, it is true that in order to deal with mismatching versions we need to modify the PATH variable, and the where command (at least, in Windows) is very handy in finding out which program gets picked first.
There's, however, a twist:
when you look at the contents of yout PATH var after running, for example,
echo %path% > path.txt
you should be aware of the fact that PATH is actually composed of TWO sections: one is System PATH and the other is Current User PATH, and it is System Path that gets evaluated first but printed last.
So simply placing a path to your, say, brand-new JDK in front of everything will be useless as long as there's another place with older version somewhere in the System PATH.
This particular problem is especially common when you have entries such as
C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\ProgramData\Oracle\Java\javapath
in your System PATH. Simply move them to the tail of your Current User PATH section to make these entries the last ones within the search queue.

Check your JAVA_HOME variable under environment variables in Windows machine. Make sure It is pointing to the version that you want.
Next check java jdk path added into your "path" environment variable. Make sure It is the version that you want, Otherwise change this to your JDK version path and then move this to the top of the list of values in path variable. This should mark your desired version as the first choice and all issues will be resolved. I did so, and everything is good.

I have a similar case but both command javac --version show the old version of sdk. It shows "javac 11.0.8" even it should be "javac 19" which is the new version just be installed.
Go to search bar > type > env
click menu "Edit the system environment variables"
Advanced tab > click on button "Environment Variables..."
Under "System Variable" > select "Path" > click "Edit"
Looking for Java path such as "C:\Program Files\Java\jdk-19\bin"
Move the path using "Move Up" or "Move Down" button to the position before "%SystemRoot%\system32" Path
OK > OK
Try the command agian.
Hope this may help you guys.

I guess when you are writing javac, it is getting the value from jre7 which is currently being used by you for development purposes and when you write java version, it is getting the value of the version from the jre8 which is currently being used by the installed applications on your system because your JRE of the system is mentioned before the jre7 which you are using for development

Why does java -version return an old version?

OS: Windows XP
I am using yuicompressor-2.4.2 to compress some CSS before uploading to my server.
But when I run it, the following exception appears:
Exception in thread "main" java.lang.UnsupportedClassVersionError:
com/yahoo/platform/yui/compressor/Bootstrap (Unsupported major.minor version 48.0)
So I think it's because of the JRE.
I typed in the command:
cmd: java -version
And it says:
java version "1.3.1_01"
But it should say 1.6.0_16, since I have installed the latest version.
What should I do to make Java use the latest version instead of the old one?

Set the environment variable JAVA_HOME pointing to the directory where you have jdk 1.6.0
set JAVA_HOME=your_path_to_jdk1.6
set PATH=%JAVA_HOME%/bin;.;..;%PATH%
That's from a command window. Also you can do it from "My PC > Properties > Advanced > Environment variables"

Go to the system32 directory C:\Windows\System32 and delete following 3 files
java.exe
javaw.exe
javaws.exe
Now create a JAVA_HOME environment variable with value={root path of your jdk installation} and add the path till bin folder of your jdk in the PATH environment variable.
Open a fresh command prompt and run java -version to confirm the change

If you are using windows 7/10 go to command prompt and type
where java
Delete all the symbolic link shows below other than your actual installation directory.
Even if correctly added all the environment variables still sometime you can get wrong versions especially when you have multiple version installed in your system and want to switch between them.

On Windows, the JRE installs a java executable in the Windows directory, which should be the first java in your path. This is just a wrapper that looks in the Windows Registry to find the Java home directory (should be "%SystemDrive%\Program Files\Java\jre6" for Java 6) and runs using the libraries there.
Run %SystemRoot%\system32\java -version and see what you get. If that is Java 6, you have entries in your path before %SystemRoot%\system32 (which really should be first). Either fix your %PATH% variable, or you'll have to be explicit whenever you want to run this version of Java.
If running that instance of java doesn't report Java 6, its not installed (correctly). Uninstall and try installing again.
If you are having trouble because of the PATH, it is because you or some software you installed monkeyed with it; I recommend using the default which is to have system32 first. Everything works fine if the defaults are used.
Also, %JAVA_HOME% is not used by the JRE itself at all. Some common Java applications like tomcat and ant honor the %JAVA_HOME% setting, so perhaps yuicompressor does too. But this is a de facto convention, not a standard.

after where java in Command prompt
for example
where java
C:\Program Files\Common Files\Oracle\Java\javapath
C:\Program Files\Java\jdk-11.0.10\bin\java.exe
delete C:\Program Files\Common Files\Oracle folder
then close all terminals and write java -version in the terminal. it will show the right version
worked for me

You should modify your PATH environment variable:
My PC > Right click > properties > Advanced > Environment variables
And modify "Path"
Append at the end the path to your 1.6 installation:
;C:\jdk1.6.xxx\bin
and remove the previous one if present.

Add %JAVA_HOME%/bin to your PATH environment variable where JAVA_HOME is set to your JRE6u16 directory

I had the same problem. In System Properties > Environment Variables > System Variables > PATH make sure there is no other path associated with Java. To make sure, type in and check Java paths.
where java
Re-open Command Prompt and type java -version again. I hope this helps.

first by the following command, you should be aware of .exe file which runs when you type java in the command prompt
where java
C:\Program Files\Common Files\Oracle\Java\javapath
C:\Program Files\Java\jdk-11.0.10\bin\java.exe
as you see above , cmd first reads java from
C:\Program Files\Common Files\Oracle\Java\javapath
so go to the path above and remove java files .
then it should work fine

You should check your PATH environment variable. It is possible that some application you have installed has put its version of the jre in front of yours in the path.

It looks like the older Java version is still on the system PATH environment variable (where the OS looks for commands) or JAVA_HOME (where yuicompressor may look for the java executable)
How those variables are changed depends on your operating system.