We Keep Coding

Cannot add java 11 jre in STS version 4.5.0

I am trying to migrate my Springboot projects from Java 8 to Java 11 although I'm having issues first on updating the installed jre of my STS. Since java 11 doesn't have any separate jre, unlike the previous versions, I was trying to include the jdk 11. Although as you can see on the bottom photo, it does not seem to locate the jrt-fs.jar file.
I've also tried to configure the SpringToolSuite4.ini file by including these lines:
-vm
C:\Program Files\Java\jdk-11.0.7\bin\javaw.exe
This is how my .ini file looks like:
Although nothing still happens. Anyone who has other pieces of advice on where I should check? Thank you in advance!

In the preference for configuring the JREs you should select the JDK folder itself, not the lib nor the bin folder. Eclipse will find all the necessary files and libraries that are included in that JDK and can deal with JDKs >= 11.
Please note that this preference is different from the VM that you specify in your ini file. The VM in the ini file is used to run the IDE itself, not to compile your projects against or run them. It is a totally separate thing, which allows you to run your IDE on JDK11 (for example), whereas at the same time you can implement and run projects on JDK8 or JDK14 (or whatever).

You are adding the lib/ dir instead of bin/.
Don't forget to add bin/ to the %Path% environment variable.
Make sure you don't have duplicates from earlier versions of the jdk/jre.
Sorry, you are adding the jdk instead of the jre that is expected:
https://www.java.com/de/download/help/download_options.xml

Unable to find a javac compiler com.sun.tools.javac.Main is not on the classpath error

I am trying to run java application and I am getting following error,
Unable to find a javac compiler; com.sun.tools.javac.Main is not on
the classpath. Perhaps JAVA_HOME does not point to the JDK
I have gone through many SO questions and found solution is JAVA_HOME should be point to JDK, not JRE.
Then I have tried to print JAVA_HOME in command prompt,
I had set this JAVA_HOME from my computer->properties->env variables -> system vars as below,
I had also added new variable in eclipse using preferences as,
And finally I am still getting the same error. Whats wrong with JAVA_HOME ?
Update :
In eclipse-preferences-installed jres there is only one entry is present and which is jdk and selected,
And under project properties java build path-libraries there is JRE System Liberary [jdk1.8.0_31] is used.
Update 1 :
C:\Program Files\Java\jdk1.8.0_31 have folder named jre. Is that jre folder causing this issue ? Can I remove this folder ? Is there is any way to add only jdk liberary in project ?

Eclipse is an IDE and as such, it has (at least) two Java versions: The one which it uses itself to run (JAVA_HOME) and a JVM which it uses to run your application. The two don't need to be the same.
So to fix your problem, you need to look into Eclipse's preferences, specifically Installed JREs which gives you a list of Java VMs which Eclipse will use to run Java code from projects. My guess is that there will be several entries there and the default will be a JRE instead of a JDK.
Make sure you have a JDK in the list and then go to your project. In the project, you can select which Java VM to use under Java Build Path -> Libraries.
[EDIT]
Look closely at the last screenshot: You've configured Eclipse to use C:\Program Files\Java\jdk1.8.0_31\jre which means you've pointed it at the JRE inside of the JDK. Use C:\Program Files\Java\jdk1.8.0_31 instead (without the \jre at the end).
[EDIT 2] If you delete the jre folder, Java will stop working. Any JDK also contains a JRE. The JRE contains rt.jar with String.class and the like. The Java compiler is in tools.jar which is in the JDK.
If recreating the JRE entry in Eclipse doesn't help, you'll have to add it manually to the classpath.
You can use a variable ("Add Variable...") to make sure Eclipse updates the path when you switch to a new/different JRE. Try JAVA_HOME with the extension lib/tools.jar

In Eclipse click Run->External Tools->External Tools Configurations
Click JRE tab
Click Installed JREs... button
Click Add button (select Standard VM, where applicable)
Click Directory Button
Browse to your JDK version (not JRE) of your installed Java (eg: C:\Program Files\Java\jdk1.7.0_04)
Click Finish.
Re-run Ant script - have fun!

I faced the same issue while i was using ant from command prompt and the solution which I found is that you need to put tools.jar inside bin folder which is present inside apache ant folder.
For eg :-
D:\apache-ant-1.10.12-bin\lib
You will get tools.jar inside
C:\Program Files\Java\jdk1.8.0_211\lib
Please change the path based on your java installation path.

JDK for Eclipse(in windows platform)

My qustion is really simple, all in the title.
After some tests I found that by given a JRE/bin directory in the path(environment variable) , Eclipse can run normally with no problem. And Eclipse will never try to find the JRE by using JAVA_HOME variable.
And in eclipse, I know that I can add installed JREs in the window preference and choose a JDK folder instead of a JRE folder. And for each project, we can change the compiler level.
Since Eclipse can also compile the codes, when is JDK used? Debug? or what?

Eclipse uses its own compiler to compile Java code. It is different than the javac compiler that comes with a JDK. In fact, you don't need a JDK to compile and run normal Java projects in Eclipse. A JRE is obviously needed to reference the required Java libraries.
However if you are using Maven or some other tools that sometimes depend on a JDK component, then you need to install a JDK on your machine. For example, Maven has an option to rely on the tools.jar that comes shipped with a JDK.

Eclipse uses the JRE you specified as default or per project settings. This could be a (only) JRE installation or a JRE from a JDK installation.
I think the more interesting question is: When should I use a JDK instead of an JRE?
The JDK includes tool that are not included in the standalone JRE. E.g. the javadoc.exe for exporting the documentation from javadoc annotated comments in the code. This Program is not included in a standalone JRE. so if you want to export your javadoc documentation you need to add an installed JRE based on a JDK installation first, so Eclipse is able to use the javadoc tool.

It could be a little hard to give a thorough answer to this but I know that at least for using Maven/m2e Eclipse needs to be run in a JDK.

First of all eclipse is a java code it wouldn't run without java installed to prove it (on your personal expence) copy the eclipse folder elsewhere and uninstal the JDK and try to run jave it wouldn't it would output the error message no JDK but instal JDK and run eclipse from the copied location it would run as a first time asking you about the workplace directory!.

Selecting the correct Java, JRE and JDK versions when building an executable JAR for distribution?

I am putting together my first Java package for distribution to users, and am running into some difficulties. I have jar packages that I've built that users can't run; the error messages vary, but are all "version" something or another. I suspect I'm selecting the wrong build paths, and I'm not quite sure where to start troubleshooting because I don't clearly understand the differences between the Java executable (javaw.exe), the JDK and the JRE; I have some questions that I'd like answered which will help in that understanding. I'm used to the way that C# executables compile in VS; wrapping my head around how executable jar files come together is still a little mysterious to me.
Although I've done a few google searches, most of what I'm finding is how to build a jar file, but not how to manipulate/use/select the Java, JRE and JDK versions appropriately to ensure compatibility. I do understand that the JRE includes the virtual machine that allows Java bytecode to run anywhere, and that the JDK includes development tools...but as to figuring out which version I AM running, vs which version is used when building jar files and which version SHOULD be used...I am completely lost.
I'm using Eclipse Indigo under 64-bit Win7. My build path includes the following:
JRE System Library: C:\Program Files\java\jre7\*
External paths: C:\<MyDocuments>\java\lib\commons-io-2.4*
I also have, installed on my machine, the following paths which are NOT included in the build:
C:\Program Files (x86)\java\jre7\
C:\Program Files (x86)\java\jre1.5.0_22\
C:\Program Files (x86)\java\jdk1.7.0_21\
The users that will be running this executable file are only supported (by corporate IT) up to JRE5. I suspect that my building this pointing it jre7 is one of the things that's messing with me.
My first stupid question is whether there's a difference between "Java" and the "JRE" when it comes to version numbers. For instance, when I read about JavaSE7 or JavaEE7, are they talking about the JRE version for the standard or enterprise editions? Are the development kits and runtime environments just components to JavaSE/EE? Or are they separate and distinct products?
Then, my understanding is that I should build this jar using the lowest-common-denominator JRE expected from my users. In this particular case, because the corporate standard is JRE5, I should build this pointing to JRE5 instead of JRE7. Is that a correct assumption?
Does it matter if I build using the 64bit or 32bit version? Some older machines may still be 32bit running JRE5, so I need to make sure I'm backwards compatible.
The Program Files (x86) naming conventions confuse me. JRE7 installed as \jre7. However, JRE5 installed as \jre1.5.0_22, and I also have jdk1.7.0_21, which, based on the JRE name, I assume to be the Java7 Development Kit. Do I need to install the Java5 Development Kit to properly build this program? And am I properly interpreting the versions from the filenames? that 1.5 represents Java5 and 1.7 represents Java7?
Then, my last question I know there's an Eclipse option to copy the external libraries to the project. I assume that if I do this, this will be included with the jar so the users do NOT need to have the Apache Commons jars on their local machines in order for this to run properly. Does the manifest include any confirmations that these files were included? I've been unable to find any references...so I'm trying to verify if I'm even pulling the Commons libraries over and where to look to get that confirmation.

This is just speculation, but I think you may have to re-write the program with the java5 jdk, because some of the APIs/libraries used in java7's jdk may not be recognized by the java5 jre. (Just like it wouldn't be possible to play PS4 games on a PS2... without any serious modding)
If you write the program in Eclipse, you can just select what library you want to use as you create the Java project. At the "Create a Java Project" screen, you can select the "Use an execution environment JRE:" or "Use a project specific JRE" or "Use default JRE" option. (I have jdk6 and jdk7 installed on my computer so I'm able to select those two options; which is why you may have install the jdk5 in order to create a java 5 project.)
You are properly interpreting the filenames. jre1.5.0_22 is java 5 update 22.
There is a way to specify which JRE is used to run the jar file.
cmd prompt >
"C:\Program Files (x86)\java\jre1.5.0_22\bin\javaw.exe" -jar "filepath_filename.jar"
Drop the "w" from the javaw.exe, and you'll be able to see any console and/or stack trace output.

Running Two Versions of Java JDK

I primarily use JDeveloper 10 with JDK 1.4.2 on Vista. I would like to install Eclipse and have it run the latest JDK 6.
Is this possible without conflict?
Ideally I would like to just use JDeveloper and switch back/forth between JDK versions. Is this possible?

It is indeed possible, you can have as many JDKs in system as you wish.
Just install them into different directories, then you can add a new JDK to your IDE (they support having multiple).
You can choose one on per-project basis.

I am not sure with JDeveloper 10, but in eclipse you can specify which installed JDK you wish you use under window>preferences>Java>Installed JREs.

You can specify the JRE for Eclipse to run under with the -vm command line switch or in eclipse.ini. e.g. -vm "%JAVA_HOME%/bin/javaw.exe"
You can specify the JRE for executed code via the Window:Preferences:Java:Installed JREs menu.

If you select project properties in Eclipse, then Java Build Path, you can choose a different JDK to use when building the project.