Develop Reference

How to uninstall Java 9 on macOS Sierra

I'm having trouble removing Java 9 from my macOS Sierra system.
I accidentally installed Java 9, instead of Java 8, so now all my Eclipse projects give me these warnings: Build path specifies execution environment JavaSE-1.8. There are no JREs installed in the workspace that are strictly compatible with this environment.
I have used the following guide, but it did not work. Here is my command output when running java -version from the command line:
java version "9"
Java(TM) SE Runtime Environment (build 9+181)
Java HotSpot(TM) 64-Bit Server VM (build 9+181, mixed mode)

for macOS high sierra removing java 9:
delete the java folder you find in the dir shown to you after executing:
/usr/libexec/java_home -V
use "Go to" in finder and copy and paste the dir to get there

There are two commands which are very simple and useful. If you want to keep multiple versions simply set JAVA_HOME to version you want to use.
export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_(version you want to use).jdk/Contents/Home
Example--> export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_161.jdk/Contents/Home
Else in addition to above command remove/uninstall additional jdk version from your system with below command.
sudo rm -rf /Library/Java/JavaVirtualMachines/jdk-(version you want to remove).jdk/
Example --> sudo rm -rf /Library/Java/JavaVirtualMachines/jdk-9.0.4.jdk/
Please refer below github link for additional details -->
https://gist.github.com/schnell18/bcb9833f725be22f6acd01f94b486392
Thanks

On MacOS you can list what JDKs you have installed and where they are installed to with:
/usr/libexec/java_home -V
If you want to select one of the installed JDKs to be used as default, you can do:
/usr/libexec/java_home -v 1.8
Verify which is now default with java -version.
You can manually add the location of other installed JREs in Eclipse via Preferences / Java / Installed JREs , press Add, and then point it to one of the locations should with the -V option above. You can then check it to select which is default for your projects.

After viewing which Java Virtual Machines I had on my computer using the following command:
ls /Library/Java/JavaVirtualMachines
I realized no additional JDK's would appear after using the Java 8 installer (besides Java 9). When doing further research, it turns out I had installed the other version that is not a SE development kit and it was just working in web browsers, not for the terminal.
For anyone having the same issue, make sure you use the Java SE Development Kit 8.

Uninstall Oracle Java using the Terminal:
Note: To uninstall Java, you must have Administrator privileges and execute the remove command either as root or by using the sudo tool.
Remove one directory and one file (a symlink), as follows:
Click on the Finder icon located in your dock
Click on the Utilities folder
Double-click on the Terminal icon
In the Terminal window Copy and Paste the commands below:
sudo rm -fr /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin
sudo rm -fr /Library/PreferencePanes/JavaControlPanel.prefPane
sudo rm -fr ~/Library/Application\ Support/Java
Do not attempt to uninstall Java by removing the Java tools from /usr/bin. This directory is part of the system software and any changes will be reset by Apple the next time you perform an update of the OS.
Source:https://www.java.com/en/

I believe the problem is navigating to the correct directory... Once you are where you are supposed to be you can run the sudo commands to remove whichever versions of java you want to remove.
First, run the command in the terminal to determine which version of Java you are running,
java -version
then you can navigate to pesky version of java that you intend to delete by using the following command:
cd /Library/Java/JavaVirtualMachines
then once you see are in the JavaVirtualMachines path, type in ls to see what versions of Java you have installed,
ls
and finally when you know which version or versions of Java you want to uninstall:
sudo rm -rf jdk-10.0.1.jdk #or whichever version you want to delete

I know that you've asked about how to uninstall the java version. But, I think it's important how to manage your Java version in a very good way.
For me, the best way is using SDKMan, a very nice tool for managing you Development tools like Java.
Here you can learn more about it: http://sdkman.io/
You can install your Java version as follow:
$ sdk install java
You can install others tools like Scala:
$ sdk install scala 2.12.1
Uninstall your tools very easy:
$ sdk uninstall java 9
And so on. Hope this helps you in future installation of your development tools.

Get Oracle Java 1.8 in windows without installing it

Is it possible to get Java in zip format? I don't want to install it by getting .exe file.
Is there any zip version of Java 1.8 so that I can download it and extract it and start using it in my Windows machine (64-bit processor)?

You can extract the JDK folder from the Installation EXE.
Check this link for the steps. The post was for JDK 1.7 it will work for JDK 1.8 also
Do the following.
Steps
Download JDK from Oracle
Download and Install 7-zip from here
Open installition exe using 7-Zip
Extract the tools.zip
Extract the content of tools.zip to a folder (e.g. c:\jdk).
Open the extracted folder in cmd prompt.
Execute for /r %x in (*.pack) do .\bin\unpack200 -r "%x" "%~dx%~px%~nx.jar" command
Set JAVA_HOME to the jdk (e.g c:\jdk) folder.
Add %JAVA_HOME%/bin to the PATH env variable.
Testing
Run the following command to check the installation, it will print the version of JDK.
c:> javac -version
javac 1.7.0_51
NOTE: Tested with JDK 1.7 and 1.8
Update 1
Edited the answer to add the steps in the answer itself instead of the link to a blog post.
Update 2
For 64-Bit please check unpack-jdk-x64.bat by grabantot

I was looking for a solution to this as well. I'm not sure why the OP wanted to do this. I'm just trying to get a newer version of java for new development while not interfering with an older Java install which a legacy application requires (I'd like to update the legacy app, but it's not an option, now)
I think the hack I am going to try is this:
Install 1.8
Take a copy of the install folder
Uninstall 1.8
Reinstall / Repair 1.7
restore the copy of 1.
I'm sure if I had a better understanding of what the install is doing, this would not be necessary.

I had a spare virtual machine hanging around (if not you could build one or maybe even download one) so I:
installed the Oracle JDK in the guest
copied the jdk folder from the guest to the host
added a JAVA_HOME environment variable.
The operating systems obviously have to be close (not sure how close, I used Windows Server 2008 64 bit guest on a Windows 10 64 bit host and it seemed to work).
Was a quick fix for me as I didn't want a full install and wanted to remove it afterwards.

If you do not have permission to unzip zip file then you cannot install java .
As java does not need installation for running . You just need to give path of java.exe where it is located .
In Windows it is located in C:\Program Files\Java\jdk1.8.0_05\bin
For a solution you can run installer on any machine that you have permission and just copy and paste the folder of java to anywhere in your system (Machine where you have administrative rights problem) . and just set the path as by opening command prompt as set path="C:\Program Files\Java\jdk1.8.0_05\bin"
java will be working as you want

The following worked for me (I had JDK 1.8 installed and needed the 32 bit version as well):
Verify the current version with java -version
Assuming a different version (minor or major is being installed), download the relevant JDK installable from Oracle and run it. In the
first dialog, specify a different folder than the default location
(might work with the default one as well), then select Next. It will
extract the files there in this folder, then it will asl for the
folder where the JRE is to be installed. Simply close the installer,
now you should have just the JDK in the specified folder.
Rerun java -version, it should give you the same version as earlier.
Worst case, if it shows the newer version, go to your system path (Right click My Computer (or This PC) -> Properties -> Advanced
system settings -> Advanced tab -> click on Environment variables
button) and remove the Oracle javapath entry (From the Path variable
in the bottom part of the window). The add the older java version's
bin folder to the path variable in the beginning.

for /r %x in (*.pack) do .\bin\unpack200 -r "%x" "%~dx%~px%~nx.jar"
Is this working for linux shell scripting , I got syntax error for the above.

How to fix error: could not find the required version of the Java(TM) 2 runtime environment in '(null)'

I have researched this and none of the solutions that I have seen have fixed my error.
What is happening is I tried to install Java EE version got the above error and then found out that I must install Java SE first. So I installed Java SE and set the JAVA_HOME variable to C:\Program Files\Java\jdk1.8.0 which is where I installed my JDK. I also put C:\Program Files\Java\jdk1.8.0\bin in my PATH variable. Still not working. I also tried the JAVA_HOME variable with C:\Program Files\Java\jdk1.8.0\bin and that didn't work. I also tried installing without the PATH variable being updated to where I put my JDK.
I'm really getting confused as to why this is happening. I've had Java before and I don't recall having this much trouble installing it.
PS I don't install from the command line I just click the download icon in Firefox and then click the download.

Try running the installer at your commandline and pass the path of the JRE instead of the JDK.
For Example:
java_ee_sdk7-windows.exe -j "C:\Program Files\Java\jre8"

I had the exact same problem and even downloading the version without JDK didn't help!
I simply installed it from the terminal with passing the JRE For Example:
java_ee_sdk7-windows.exe -j "C:\Program Files\Java\jre7"
and it worked like a charm!

I had the same problem but an additional step was required in order to install using the command line. In the command window (on my Windows 10 laptop) I had to use:
cmd /d
to tell the cmd window to ignore registry AutoRun commands before the java installation executable would run. After using cmd /d, and changing to the directory where the .exe file was at, the following worked:
java_ee_sdk-6u4-jdk7-windows-x64.exe -j "%JAVA_HOME%"
Where JAVA_HOME is a system environment variable pointing to an existing JDK installation (C:\Program Files\Java\jdk1.8.0_65).

Uninstall everything, all of it.
Then go to your Program Files folder (and (x86) folder if on a 64bit Windows) and physically remove any Java folders.
Reinstall Java SE and then the EE packages. Sometimes Windows appears to get a bit confused and you need to help it figure out what to do.

If you want to uninstall, go to the glassfish folder and open the command prompt, then type:
uninstall.exe -j <The path to your JRE>

These points may be helpful.
java EE SDK7 contains glassfish v4.0 and it compatible with JDK6 and JDK7.
java EE SDK8 contains glassfish v5.0, it compatible with only JDK7 and JDK8, not JDK 9 or beyond.
So environment variable JAVA_HOME has to point to the root directory of one of the mentioned JDK. and %JAVA_HOME%\bin should be added to environment variable path
Despite having followed all of the above, setup of java EE SDK7 gets error:
could not find the required version of the Java(TM;
as Bakudan and laf8 said,
open cmd using run, with /d /a options as followed.
cmd /d /a
and next run SDK7-setup with -j option like this command
sdk7.exe -j "%JAVA_HOME%"
note that %JAVA_HOME% enclosed BY ""

This was happening to me when I tried to run the Java EE installer. What I did, was to download from Oracle a Java EE version which didn't include the JDK, because it was already installed in my system. Problem solved!

Open regedit.
goto :HKEY_LOCAL_MACHINE\Software\JavaSoft\Java Runtime Environment\
set CurrentVersion to desired JDK version.
Check JavaHome and RuntimeLib path's for selected jdk version folder
Check JavaHome and RuntimeLib path's for selected jdk version folder
example: "HKEY_LOCAL_MACHINE\Software\JavaSoft\Java Runtime Environment\1.7".
example:
JavaHome=C:\Program Files (x86)\Java\jdk1.7.0_79
RuntimeLib=C:\Program Files (x86)\Java\jdk1.7.0_79\jre\bin\server\jvm.dll
Source: http://tech-read.com/2009/05/19/how-to-solve-error-could-not-find-java-runtime-2-environment-while-opening-an-ide/

Change java version (Mac)

I have 2 java versions on my computer:
/Library/Java/JavaVirtualMachines/jdk1.7.0_07.jdk/Contents/Home
/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
The 1.6.0 is set to default. How can I make my java programs to run 1.7?
Tried to add:
export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.7.0_07.jdk/Contents/Home
to my .zshrc file. But this seems to only change the path for my terminals java command.
Also tried to change the HOME symlink like this:
cd /Library/Java
mv Home Home-1.6
ln -s /Library/Java/JavaVirtualMachines/jdk1.7.0_07.jdk/Contents/Home/ Home
This had no effect at all.
Also tried java changer software:
http://www.guigarage.com/2013/02/change-java-version-on-mac-os/
But no effect.
Any idea how to start java programs like .app and .jar files with the 1.7 version by just clicking on them?

I believe OS X (at least 10.8) uses the following paths:
JRE: /System/Library/Frameworks/JavaVM.framework/Versions/Current
JDK: /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK
Those are symlinks, which you can update to point to your 1.7 installation.
You can verify this fairly easily:
a) run which java to check which java executable is being executed. In theory, that should be /usr/bin/java.
b) run ls -la on your java executable, which should tell you where it points (/System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java
on my machine).
I think this should sort your .jar execution issue. If your Java application is wrapped in a .app, I believe it's a bit more complex: if memory serves, the version of java used will depend on the JavaApplicationStub being used by the .app.

$ edit ~/.profile
#Java 1.8
export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_20.jdk/Contents/Home
export PATH=${PATH}:${JAVA_HOME}
$ java -version
java version "1.8.0_20-ea"
here are the steps:
http://ukitech.blogspot.com/2014/04/switching-version-of-java-on-mac.html

You can always add into your profile both on Mac or Linux. Just create if doesn't exist ~/.profile file and there this line:
export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.7.0_07.jdk/Contents/Home
This should work .zshrc as well as .bash_profile are loaded only when terminal window is openned and profile when your graphical environment starts up.

Switch from open jdk to Sun jdk

I have jdk1.7.0 directory in /usr/lib/jvm along with other open-jdk versions. I want my Ubuntu 12.04 to treat this jdk(jdk1.7.0) as its primary jdk i.e. I dont want to use open-jdks.
When I type java -version or javac -version, both the times it returns that it is using openjdk and its jre. How can change it to jdk1.7.0?

Put something similar to following to your ~/.bashrc
export JAVA_HOME="/usr/lib/jvm/jdk1.7.0"
export PATH="$JAVA_HOME/bin:$PATH"
for loading the changes, you can just run new bash by typing "bash" :]

Change the PATH variable so that /usr/lib/jvm is listed before the directory which contains Open JDK. If you are using bash, you can do this in the .bashrc file in your home directory.