I am using Windows XP 32 bit system. I have java directory in my C:
Also when I searched, I found that Java is installed in C:\Windows\system32\ directory.
When I run java -version command in my command prompt, I got below result:
java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) Client VM (build 24.45-b08, mixed mode, sharing)
I am able to run Java program in eclipse in my system.
I installed BlueJ in my system. When I open it, I got a pop up informing me that "BlueJ could not find a Java Development Kit. A JDK must be installed to run BlueJ. Click browse to locate JDK." I am not able to locate JDK in my system.
Can someone help me to locate JDK in my system?
You have most probably installed Java Runtime Environment (JRE) and not Java Development Kit (JDK)
A simple explanation is that you need JRE to run Java Programs and JDK to create them. BlueJ is an IDE for developing Java programs, so it will need JDK.
You can download it from here:
http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html
Make sure you choose the correct version for you OS (Windows, x86)
Related
I am new to Java programming. I have installed Java SE 11 (LTS) (JDK 11.0.8) on my OS. Note that former Java also has jre folder in it. But Java 11 onward there come only JDK folder.
So, I have set JAVA_HOME environment variable as well as, included jdk\bin in path as well.
By checking on cmd java version shows as follow:
C:\Users\user>java -version
java version "11.0.8" 2020-07-14 LTS
Java(TM) SE Runtime Environment 18.9 (build 11.0.8+10-LTS)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.8+10-LTS, mixed mode)
Then I installed eclipse 2020 09 version. But by making a simple Hello World project does not work.
And shows this error multiple times.
Description Resource Path Location TypeThe project was not built due to "Failed to init ct.sym for C:\Users\Irfan Umar\AppData\Local\Temp\eoiE758.tmp\plugins\org.eclipse.justj.openjdk.hotspot.jre.minimal.stripped.win32.x86_64_14.0.2.v20200815-0932\jre\lib\jrt-fs.jar". Fix the problem, then try refreshing this project and building it since it may be inconsistent HelloWorld Unknown Java Problem
What is the solution, I believe it is related to JRE not provided in JDK now.
Eclipse uses Java in two ways. It runs Eclipse with Java, and it allows specifying Java Runtime Environments in Preferences. I rarely see any reason to set JAVA_HOME anymore, because I specify the paths to the JDKs I want to use. I always have multiple JDKs installed.
I specify which JDK to use to run Java by setting the "-vm" path in the "eclipse.ini" file (which points to the "bin" directory).
I specify which JDK to use to compile code by adding JREs in preferences, and sometimes editing the "Execution Environments" (subsection of "Java Runtime Environments") to point to specific JREs.
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 was running SQL workbench on my mac, and it is complaining that it needs java 8, but instead it found java 10.0.1 on my computer. So I need to locate the java executable and find ways to downgrade the java version. However, I got totally lost when I was looking for the java version.
When I run '/usr/libexec/java_home -V' from terminal, I get this:
Matching Java Virtual Machines (3):
9.0.4, x86_64: "Java SE 9.0.4" /Library/Java/JavaVirtualMachines/jdk-9.0.4.jdk/Contents/Home
When I run 'java -version', I get below, which means that it is pointing to the java 9.0.4 listed above:
java version "9.0.4"
Java(TM) SE Runtime Environment (build 9.0.4+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.4+11, mixed mode)
However, when I check java control panel under 'System Preferences', it shows that my current java version is 10.0.1 under the tab 'General'. Under tab 'Desktop Settings', the listed JRE path is '/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java'. So, it looks like the software (SQL workbench) is complaining about this java version. But how come it is not the java version I got from terminal (9.0.4)? Which java is actually running on my Mac in this case? If I want to change the java 10 listed under java control panel, what should I do?
Thanks!
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 just tried to run Eclipse on a Mac Book Pro running OSX Mavericks. I've downloaded both, the 32 and the 64 bit version. Both end up in following Notification:
Version 1.6.0_65 of the JVM is not suitable for this product.
Version: 1.7 or greater is required.
I know that the question was already asked, but my Eclipse won't event start with the 64-bit version, which was the answer for a smiliar question. So I checked the version of my installed Java by running
java -version
In the terminal. The output really confirmed, that version 1.6.0_65 was installed. Here's the output:
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)
Now the problem is that when launching the Java Control panel, it says, that Java 7 Update 67 is installed, and there are no updates.
So where's my problem, how get I get Eclipse to run?
You can modify the eclipse.ini and add the path to your JDK7
For versions of Mac OS X 10.7+ the location has changed to
-vm
/Library/Java/JavaVirtualMachines/<''jdk_name_ver''>/Contents/Home/...
To be safer, determine the location for the JDK you intend to use via the utility /usr/libexec/java_home and put this value with .../bin/java appended into the eclipse.ini file.
See "How to install JRE 1.7 on Mac OS X and use it with Eclipse?"
I installed JDK, "Java SE Development Kit 8u101", in addition to JRE and eclipse started to work fine.