Is PyCharm made using Java-Swing?
If it is, then how does it runs on a PC where JDK or JRE hasn't been set up yet?
When I look at my own PyCharm installation directory structure, I see a jre64 directory, which contains a Java installation.
And that seems to be a normal JRE:
$ ./pycharm-community-2018.2.4/jre64/bin/java -version
openjdk version "1.8.0_152-release"
OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b8)
OpenJDK 64-Bit Server VM (build 25.152-b8, mixed mode)
So PyCharm comes with a Java distribution which it uses (even instead of an already available Java installation). Instead of my pre-installed and configured java 1.8.0_191, it uses the version it comes bundled with:
Related
Following the posts here and here, I had to have two different versions of Java/OpenJDK installed
brew install java
brew cask install java
now I have openjdk 13.0.2
openjdk 13.0.2 2020-01-14
OpenJDK Runtime Environment (build 13.0.2+8)
OpenJDK 64-Bit Server VM (build 13.0.2+8, mixed mode, sharing)
in two different locations
/usr/local/opt/openjdk/bin
/usr/local/opt/openjdk/libexec/openjdk.jdk/Contents/Home/bin/
and openjdk 14
openjdk 14 2020-03-17
OpenJDK Runtime Environment (build 14+36-1461)
OpenJDK 64-Bit Server VM (build 14+36-1461, mixed mode, sharing)
also in two different locations
/System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/
/Library/Java/JavaVirtualMachines/openjdk-14.jdk/Contents/Home/bin/
so my questions are
why there are two different locations for each installation of OpenJDK?
how to find out if there are more installations of JDK on my system? Ran sudo find / -name java which nuked my terminal (see log here).
How to know how those different versions of java are installed?
I understand that JDK is Java SDK and JRE (Java Runtime Environment) is an oracle thing which I think OpenJDK doesn't have (?) but looking at OpenJDK download page what are "JMC" and "Java SE"?!
what you are seeing is the way that a JDK works on macOS. but basically what you should know that we have two entities called JDK and JRE. JDK is a tool for java developers to compile and run their applications. JRE is a runtime for clients to run java applications. JDK is containing a JRE, so you don't need to install JRE when you have JDK.
A JDK is a folder that you can have based on your OS and copy paste it every where that you need and just add the bin folder to your PATH . so you might have lot of JDK folders but only the one that is added to your PATH is your current working JDK, and they are not working at the same time in one environment but you can have multiple Java versions on different user profiles.
what you have is one installation with its meta data and links all over the macOS.
you can have multiple JDK folders all around your hard disk but only one of them at the current time is working and that would be the one that you have in the user profile.
I don't know a way to find out how they are installed. you can query the tools like brew in your os to find out that if they installed any java or not but not from JDK itself.
JMC is java mission control which is a monitoring application for java application. JRE, as I said, is a runtime for running the applications and OpenJDK also includes a runtime in itself. JavaSE is the specification of Java for Standard edition since we have other editions too.
I am trying to install eclipse-cpp oxygen on macOS Sierra 10.12. While installing it i get an error that java version is not 1.8, while I had already installed latest JDK package. on terminal it shows java version as below
java version "1.6.0_65"
Java(TM) SE Runtime Environment (build 1.6.0_65-b14-468-11M4833)
Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-468, mixed mode)
Please suggest how can I upgrade my java version.
Apple don't provide a version of Java greater than Java 6. You must install Java 8 from the Oracle site.
In order to run Eclipse you must install the full JDK, the JRE download is not enough as it does not include the java executable.
The Oracle site is here
You can install Java8 from here.
http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
make sure to check the latest binaries of java and javac in PATH. You can override the old java binaries in path.
it opens a web browser and a page tells me that I have to install either JRE or JDK version 1.7.0 or higher. I have installed JRE 1.8.0, in fact in command line I can see:
d:>java -version
java version "1.8.0_121"
Java(TM) SE Runtime Environment (build 1.8.0_121-b13)
Java HotSpot(TM) Client VM (build 25.121-b13, mixed mode)
I also setup JAVA_HOME and PATH accordingly but no luck. Is there something else I can try?
Thanks
I found the issue: I installed JRE X86 while Eclispe wanted the X64 version. I have installed it now and the installation process goes on. I didn't install JDK because I want Eclipse for C++ I don't need Java things. Thanks anyway, I hope this will help others!
You need the JDK installed to run Eclipse, or even better, to develope java apps at all...
verify that by doing in a terminal:
>javac -version
I downloaded Eclipse Luna and ran from the terminal in Mac OS X:
> /Applications/Eclipse.app/Contents/MacOS/eclipse
JavaVM: requested Java version (1.8.0) not available. Using Java at "/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home" instead.
However, I have:
> java -version
java version "1.8.0_20"
Java(TM) SE Runtime Environment (build 1.8.0_20-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.20-b23, mixed mode)
What am I doing wrong?
Luna seems currently having a bug: it installs the wrong Java version as its own dependency and then fails claiming that version is wrong.
You need to install Java separately (download official SDK from Oracle website) and make that one default. Be sure you install SDK and not the web plugin. Type java -version to verify the version and then which java to tell the exact path. Edit eclipse.ini as usual and set there the correct path to Java executable.
I downloaded JDK for Mac OS X 10.9.1 from Oracle, but I had to install another Java from Apple site once more, as I couldn't launch eclipse with it.
These are two pages that I referred.
Installing Java on OS X 10.9 (Mavericks)
http://support.apple.com/kb/DL1572?viewlocale=en_US
Now I have three java binaries installed in my computer.
Installation A
/System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java
java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)
Installation B
/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/bin/java
java version "1.6.0_65"
Java(TM) SE Runtime Environment (build 1.6.0_65-b14-462-11M4609)
Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-462, mixed mode)
Installation C
/Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/bin/java
java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)
I found that I can easily remove Installation C, however I'm not sure if this is OK.
When I invoked java from command line, it points to Installation A.
java -version
java version "1.7.0_51"
ls -alF `which java`
lrwxr-xr-x 1 root wheel 74 Jan 15 09:12 /usr/bin/java# -> /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java
Is there any way to use just one JDK 1.7 for Mavericks by removing two of them safely?
EDIT
After some setup and test, I have only one Java (1.6) installed.
I have Installation B, and now Installation C is linked to Installation A.
For using eclipse, I had to make Compiler Compliance level to 1.6 to use it (from the help java.lang.UnsupportedClassVersionError Unsupported major.minor version 51.0).
EDIT2
This seems to what happened.
Installation of Apple Java
Installation A
Installation B is a symbolic link to A
Installation of Oracle Java
Installation C
Changed the Installation B that
Created a /System/Library/Frameworks/JavaVM.framework/Versions/A
Copied files from Installation C (not symbolic link)
Make a symlink Current to Versions/A
I tried to install Oracle Java only by removing Apple Java, but I got installation error, so I guess Apple Java is needed to install Oracle Java.
Specify the JVM for Eclipse
You can specify JDK version for usage with Eclipse in eclipse.ini. This will resolve problem with starting Eclipse.
-vm
/Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/bin/java
Warning: Add this configuration before -vmargs.
Master your Java Environnement with jenv
It is much easier to maintain multiple JDK versions with jenv.
jenv is for a equivalent of rbenv, but for Java environnement. It allow to easily switch between several JDKs installations (already presents), and configure which one to use per project.
Eclipse JDK
Setting JDK in Eclipse
It seems like that the oracle JDK can be just removed. For eclipse, I could add Installation A as a default JRE from Java Build Path -> JRE System Library -> Installed JRES -> Add ...