I'm a bit confused now. When I run the command java --version in the terminal i get: java 13.0.1. When I open the system preferences and click the java app and then about, i see it says Java version 8 1.8.0_231
Does that mean I have 8, 13 or both?
When I check through the java app.
When I check through the terminal.
When i check for all JDK installed on my system (only 1 version pop ups).
You can have multiple JDK installed in one machine but you can have only one version set as default Java SDK. Looks like you have Java 13 set as default.
Try running the following :
echo $JAVA_HOME
You can also go to the tab Java and see the list of all Java Runtime Environments (JRE.)
Please note that just because you have multiple JREs available doesnot mean all corresponding SDK are also there.
You can have many version of java on your Mac. But you can run only one of this in a process.
On my Mac, system preferences run with java path :
/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java
But in terminal, this run with java path:
/usr/bin/java
I think you can replace java file in /usr/bin by another version java you want.
that means you jdk version is 13 , and your jre version is 1.8.
jre is used for running java apps ,and the jdk(java development kit) is for building apps with java language. java jdk is like the android sdk
usually when installing an updated JRE, the environment variables will be set so that running any java command in CMD will use the new version.
I've just installed JDK 11 which doesn't have a JRE equivalent - well it's in the JDK - but java commands are still being sent to JRE 8.
This is no problem for me, I can always change the environment vars myself and point to "C:\Program Files/java/jdk-11/bin/java.exe", but anyone who wants to use my program, which requires Java 11, will not have their variables set and it's a bit much to ask them to do so.
Why are they not being set on a standard Java 11 install? Am I being stupid?
Oracle is still pushing 8 as the "end user" Java install. That's why it's the only one you can find on java.com. Newer versions of Java are designed either for back-end use on servers, or to be bundled with the application itself. The latter option is what you want.
I am trying to install something via a jar file:
java -jar filename.jar'
I then get this error:
You need at least Java version 1.7 to run the installer.
However, you appear to be running version 1.8.0_20.
Please run the installer with the requisite Java version.
Aborting...
I am still kinda new to this, but doesn't this mean it needs Java 1.7 or higher and I am running 1.8?
How would I go about fixing this?
Java 8 has some bugs right now... Just install Java 7 alongside Java 8 and it should work
If you cant find a download, here's a link to the official Oracle site with at least Java SE 7:
http://www.oracle.com/technetwork/java/javase/archive-139210.html
I am trying to run neo4j for the first time.
In my RHEL 6 machine, I have Java 1.6 installed. I do not want to change that because other programs are using that. When I tried to run neo4j, downloaded from here, I got the error: ERROR! Neo4j cannot be started using java version 1.6.0_24. Please use Oracle(R) Java(TM) 7. Clearly, I need to install JAVA 7. I was wondering if I can just download Java 7 and let neo4j know the path to java executables.
Set the JAVA_HOME and PATH before starting the neo4j server.
set the path on the terminal.
export JAVA_HOME=/home/jdk/jdk1.7.0_45
export PATH=$JAVA_HOME/bin:$PATH
then start the neo4j or you can create a bash script to do this automatically.
The different major versions are normally different packages (e.g., java-1.7.0-openjdk-devel) that go in different directories (usually in /opt), and you can set the JAVA_HOME and/or JDK_HOME environment variables in your startup script. That said, there's rarely any harm in running your programs on the version 7 JVM (just like you can upgrade the kernel without touching your installed programs), and Java 6 is EOL and won't get new security updates.
neo4j 2.0.2 uses java7 it seems and hence requires jdk7.
Go to neo4j website and download 1.8.3 version
http://dist.neo4j.org/neo4j-community-1.8.3-unix.tar.gz
and if you have java 1.6.45 in ubuntu, you are done
untar and copy to /opt and issue the below command from neo4j root directory
sudo ./bin/neo4j start
We have a couple of applications running on Java 5 and would like now to bring in an application based on Java 6. Can both java versions live together under Windows?
Is there any control panel to set the appropriate Java version for different applications, or any other way to set up, what version of Java will be used to run that particular application?
Of course you can use multiple versions of Java under Windows. And different applications can use different Java versions. How is your application started? Usually you will have a batch file where there is something like
java ...
This will search the Java executable using the PATH variable. So if Java 5 is first on the PATH, you will have problems running a Java 6 application. You should then modify the batch file to use a certain Java version e.g. by defining a environment variable JAVA6HOME with the value C:\java\java6 (if Java 6 is installed in this directory) and change the batch file calling
%JAVA6HOME%\bin\java ...
I was appalled at the clumsiness of the CLASSPATH, JAVA_HOME, and PATH ideas, in Windows, to keep track of Java files. I got here, because of multiple JREs, and how to content with it. Without regurgitating information, from a guy much more clever than me, I would rather point to to his article on this issue, which for me, resolves it perfectly.
Article by: Ted Neward: Multiple Java Homes: Giving Java Apps Their Own JRE
With the exponential growth of Java as a server-side development language has come an equivablent
exponential growth in Java development tools, environments, frameworks, and extensions.
Unfortunately, not all of these tools play nicely together under the same Java VM installation. Some
require a Servlet 2.1-compliant environment, some require 2.2. Some only run under JDK 1.2 or above,
some under JDK 1.1 (and no higher). Some require the "com.sun.swing" packages from pre-Swing 1.0
days, others require the "javax.swing" package names.
Worse yet, this problem can be found even within the corporate enterprise, as systems developed using
Java from just six months ago may suddenly "not work" due to the installation of some Java Extension
required by a new (seemingly unrelated) application release. This can complicate deployment of Java
applications across the corporation, and lead customers to wonder precisely why, five years after the
start of the infamous "Installing-this-app-breaks-my-system" woes began with Microsoft's DLL schemes,
we still haven't progressed much beyond that. (In fact, the new .NET initiative actually seeks to solve the
infamous "DLL-Hell" problem just described.)
This paper describes how to configure a Java installation such that a given application receives its own,
private, JRE, allowing multiple Java environments to coexist without driving customers (or system
administrators) insane...
It is absolutely possible to install side-by-side several JRE/JDK versions. Moreover, you don't have to do anything special for that to happen, as Sun is creating a different folder for each (under Program Files).
There is no control panel to check which JRE works for each application. Basically, the JRE that will work would be the first in your PATH environment variable. You can change that, or the JAVA_HOME variable, or create specific cmd/bat files to launch the applications you desire, each with a different JRE in path.
We can install multiple versions of Java Development kits on the same machine using SDKMan.
Some points about SDKMan are as following:
SDKMan is free to use and it is developed by the open source community.
SDKMan is written in bash and it only requires curl and zip/unzip programs to be present on your system.
SDKMan can install around 29 Software Development Kits for the JVM such as Java, Groovy, Scala, Kotlin and Ceylon. Ant, Gradle, Grails, Maven, SBT, Spark, Spring Boot, Vert.x.
We do not need to worry about setting the _HOME and PATH environment variables because SDKMan handles it automatically.
SDKMan can run on any UNIX based platforms such as Mac OSX, Linux, Cygwin, Solaris and FreeBSD and we can install it using following commands:
$ curl -s "https://get.sdkman.io" | bash
$ source "$HOME/.sdkman/bin/sdkman-init.sh"
Because SDKMan is written in bash and only requires curl and zip/unzip to be present on your system. You can install SDKMan on windows as well either by first installing Cygwin or Git Bash for Windows environment and then running above commands.
Command sdk list java will give us a list of java versions which we can install using SDKMan.
Installing Java 8
$ sdk install java 8.0.201-oracle
Installing Java 9
$ sdk install java 9.0.4-open
Installing Java 11
$ sdk install java 11.0.2-open
Uninstalling a Java version
In case you want to uninstall any JDK version e.g., 11.0.2-open you can do that as follows:
$ sdk uninstall java 11.0.2-open
Switching current Java version
If you want to activate one version of JDK for all terminals and applications, you can use the command
sdk default java <your-java_version>
Above commands will also update the PATH and JAVA_HOME variables automatically. You can read more on my article How to Install Multiple Versions of Java on the Same Machine.
It should be possible changing setting the JAVA_HOME environment variable differently for specific applications.
When starting from the command line or from a batch script you can use set JAVA_HOME=C:\...\j2dskXXX to change the JAVA_HOME environment.
It is possible that you also need to change the PATH environment variable to use the correct java binary. To do this you can use set PATH=%JAVA_HOME%\bin;%PATH%.
I use a simple script when starting JMeter with my own java version
setlocal
set JAVA_HOME="c:\java8"
set PATH=%JAVA_HOME%\bin;%PATH%;
java -version
To have a java "portable"
you can use this method here:
https://www.whitebyte.info/programming/java/how-to-install-a-portable-jdk-in-windows-without-admin-rights
Or use links. While it is rather unpleasant to update the PATH in a running environment, it's easy to recreate a link to a new version of JRE/JDK. So:
install different versions of JDK you want to use
create a link to that folder either by junction or by built-in mklink command
set the PATH to the link
If other version of java is to be used, delete the link, create a new one, PATH/JAVA_HOME/hardcoded scripts remain untouched
Invoking Java with "java -version:1.5", etc. should run with the correct version of Java. (Obviously replace 1.5 with the version you want.)
If Java is properly installed on Windows there are paths to the vm for each version stored in the registry which it uses so you don't need to mess about with environment versions on Windows.
If you use Java Web Start (you can start applications from any URL, even the local file system) it will take care of finding the right version for your application.
Using Java Web Start, you can install multiple JRE, then call what you need.
On win, you can make a .bat file:
1- online version:
<your_JRE_version\bin\javaws.exe> -localfile -J-Djnlp.application.href=<the url of .jnlp file.jnlp> -localfile -J "<path_temp_jnlp_file_.jnlp>"
2- launch from cache:
<your_JRE_version\bin\javaws.exe> -localfile -J "<path_of_your_local_jnlp_file.jnlp>"