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.

Choose updated Java SDK in mac from available different version

I'm using mac machine for native-script development and while executing an program it thrown an java error that:
Javac version 1.6.0_65 is not supported. You have to install at least 1.8.0.
so I checked with available install version on developer machine & found two different version detail:
/usr/bin/java -version Showing 1.6.
while system preference -> java control panel -> update. showing V1.8
any suggestion why two version !! Am I missing something here?
Update1: Following help to understand how mac handling this: /usr/bin/java is machine default location, and /Library/Internet.. which is manage explicit.
sudo rm /usr/bin/java
sudo ln -s /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java /usr/bin
In my case I update default one with downloaded from internet.
Reference link Link1, Link2

You should use /usr/libexec/java_home instead
> /usr/libexec/java_home
/Library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home
you can use it to set JAVA_HOME
export JAVA_HOME=$(/usr/libexec/java_home)
then, you can put this one inside ~/.profile so you have always JAVA_HOME set to most recent release.

What is the recommended approach to switch between java 7 and java 8 in Linux (Ubuntu)?

I have a linux box (Ubuntu server 14.04). I installed jdk7 via apt-get and Oracles Java 8 manually by extracting the tarball.
How can I switch between the Java versions from a bash session?
I suppose it should be done via "alternatives", but the details are not clear to me.
Switching java is more than calling one of the two java executables. There are other binaries (e.g. javac) and some tools refer to different files within the java installation directories (think of cacerts for example).
An optimal solution would simulate the effects of having only one of the two versions installed at any time.
Example: Using maven it is possible to set JAVA_HOME, but if some process started by maven calls java, JAVA_HOME is ignored.
I think Debian has Java 8 meanwhile. Does anybody know how they deal with this issue?
Is the alternatives mechanism only usable for individual binaries or can it be used for a complete "suite", too?

You can use this command to get a list of installed jdk's and easily choose one you would like to use:
sudo update-alternatives --config javac

I'm not sure that I fully understand the question, but you could either use an environment variable in your bash session that holds the path to your java executable or you could put a symbolic link somewhere for the same purpose.
For example
export JAVA_EXEC=/usr/lib/jvm/java-8-oracle/jre/bin/java
$JAVA_EXEC -version
$JAVA_EXEC -jar cooljar.jar
Or with symlink, like the "alternatives" you mentioned
ln -s /usr/lib/jvm/java-8-oracle/jre/bin/java /usr/local/bin/java
/usr/local/bin/java -version
ln -s "${SOME_JAVA_PATH}" /usr/local/bin/java
/usr/local/bin/java -version

How do I install an earlier version of Java SDK on OSX

I have the Java 1.8.0_45 SDK installed on OSX Yosemite (10.10.4), but because of a bug in this release I need to go back to 1.8.0_25
I have downloaded and installed the earlier version (1.8.0_25) but even after a reboot java -versionstill shows 1.8.0_45.
I don't really understand where Java resides on OSX, but how can I get my system back so it uses 1.8.0_25

Try and add this to your ~/.bashrc
export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.7.0_75.jdk/Contents/Home
You can have multiple JRE/JDK's installed, by changing this path, you can specify which one you use each time you open a new shell.
Here is what I use in my .bashrc
JAVA_VERSION=7
JAVA_7_HOME=/Library/Java/JavaVirtualMachines/jdk1.7.0_75.jdk/Contents/Home
JAVA_8_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_40.jdk/Contents/Home
tmp="JAVA_${JAVA_VERSION}_HOME"
export JAVA_HOME=${!tmp}
export PATH=${!j}/bin:$PATH
Here, you can simply change the 7 to an 8.
This will change the JAVA_HOME, and append the bin directory to your path for general use from the command line.
note you may beed to change your java home's according to the specific release versions installed on your machine.

Ah found it, suprisingly easy:
macbook:JavaVirtualMachines paul$ cd /Library/Java/JavaVirtualMachines
macbook:JavaVirtualMachines paul$ ls
jdk1.7.0_40.jdk jdk1.7.0_45.jdk jdk1.8.0.jdk jdk1.8.0_05.jdk jdk1.8.0_20.jdk jdk1.8.0_25.jdk jdk1.8.0_45.jdk
macbook:JavaVirtualMachines paul$ sudo rm -fr jdk1.8.0_45

JRE error when trying to install Matlab Compiler Runtime

Once again, I spent much time trying to get something to work without success.
I want to install MATLAB Compiler Runtime on my Ubuntu 13.04, where there is no MATLAB installed.
Here's what I did:
I downloaded the 64-bit Linux version R2012b(8.0) off of
http://www.mathworks.com/products/compiler/mcr/index.html?s_cid=BB.
Then, I switched into the folder and tried to install via
sudo ./install just to receive the following message:
Error: Cannot locate Java Runtime Environment (JRE).
The directory /home/konni/Downloads/MCR_R2012b_glnxa64_installer/sys/java/jre/glnx86/jre does not exist.
And, it does not exist indeed, but there exists a folder with "glnxa86" instead of "glnx86". I wouldn't just want to rename it, though.
I do have a JRE installed on my machine, btw:
java version "1.7.0_25"
OpenJDK Runtime Environment (IcedTea 2.3.10) (7u25-2.3.10-1ubuntu0.13.04.2)
OpenJDK Server VM (build 23.7-b01, mixed mode)
I have absolutely no clue what to do. The problems I found using google didn't quite help me, either...
Maybe you have an idea?
I'd greatly appreciate any help! :-)

If the only problem is finding the JRE, then the command line switch -javadir will get you done:
./install -javadir /usr/lib/jvm/java-7-openjdk-i386/jre/

I had the same problem recently when installing a software that required a 7.13 MCR on an Ubuntu 17.10.
In this
https://www.linuxquestions.org/questions/linux-newbie-8/matlab-7-5-compiled-runtime-for-64-bit-linux-installation-no-jre-error-838281/
I found that the 32 bit version installs fine, and it did, but obviously, that didn't solve my problem.
However, I found a way to do it. The trick is that the installer needs the old JRE (1.5) and will not work with JDK 8.
So the first step is to run
./MCRInstaller.bin -is:extract
this will create a directory called istemp... something, for me istemp23732345211606.
ls
jre1.5.0-linux-amd64.bin JVMNotFound.txt setup.jar Verify.jar
It is tempting to run the setup.jar directly, do try, but with Java 8, I only got the following error message:
Could not load wizard specified in /wizard.inf (104)
But perhaps it will work for you. People who get the above mentioned error with wizard.inf should look further, because the installer needs JDK 5 to run.
I chose not to use the bundled version but downloaded the JDK 5 from Oracle. The bundled version might work as well - I did not try.
You can download JDK 5 from here:
http://www.oracle.com/technetwork/java/javasebusiness/downloads/java-archive-downloads-javase5-419410.html#jdk-1.5.0_22-oth-JPR
Extract the downloaded archive (chmod +x the bin and run), then copy the files to /usr/lib/jvm/java5
Rename the jdk1.5.0_022 or anything to jdk1.5.0 to make it simple.
Fix attributes:
sudo chmod a+x /usr/bin/java
sudo chmod a+x /usr/bin/javac
sudo chmod a+x /usr/bin/javaws
sudo chown -R root:root /usr/lib/jvm/java5/jdk1.5.0
Then run:
sudo update-alternatives --install "/usr/bin/java" "java" "/usr/lib/jvm/java5/jdk1.5.0/bin/java" 1
sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/lib/jvm/java5/jdk1.5.0/bin/javac" 1
Now chose the jdk 5 as default
sudo update-alternatives --config java
And selecting the appropriate option.
Check that it worked
java -version
You should see something like this:
java version "1.5.0_22" Java(TM) 2 Runtime Environment, Standard
Edition (build 1.5.0_22-b03) Java HotSpot(TM) 64-Bit Server VM (build
1.5.0_22-b03, mixed mode)
Now you can run the setup.jar file in the extracted directory (istemp...)
sudo java -jar setup.jar
I recommend that you chose a contemporary java by running
sudo update-alternatives --config java
again.

When running the installer.sh, use the command line option "-is:javahome [path to your java jre folder]".
For instance, I installed below a java 8 jre on an old matlab compiler 2007b as follow:
sudo /opt/installer.sh -console -is:javahome /usr/lib/jvm/java-8-openjdk-amd64/jre/

I had same problem. The problem is you are installing 64-bit matlab on 32-bit ubuntu. use 32-bit matlab and install in ubuntu 32-bit. use 64-bit matlab and install in ubuntu 64-bit. Please like the answer if it was helpful.