Java 6/7 Compatibility

[lousakura]

Hello!
I was wondering if it would be possible to add compatibility for java 6 or 7, because I wanted to be able to run the launcher on older OSes, thank you :)

[K4sum1]

I was going to test this as well, but guess I don't need to. It would be nice to have it work with Java 6 like the old launcher did.

[bigfoot547]

When I made this, I wasn't aware people still cared about Java 6. As such, it's not officially supported. Maybe try building it yourself with a java 6 JDK? I've never tried it.

[lousakura]

Alright thanks for answering

[K4sum1]

Can't just give up that easily lol. Will try building it myself

[lousakura]

Okay, so I tried building it in Java 6 but couldn't as Maven 3.3.1+ requires JDK 7+ and I'm new to all of this so I don't know how to fix it.

[lousakura]

After that I tried building it in Java 7 and this happened.

[INFO] Scanning for projects...
[ERROR] [ERROR] Some problems were encountered while processing the POMs:
[ERROR] Child module C:\Users\luisc\Downloads\olauncher\olauncher\pom.xml of C:\Users\luisc\Downloads\olauncher\pom.xml does not exist @
@
[ERROR] The build could not read 1 project -> [Help 1]
[ERROR]
[ERROR] The project dev.figboot:olauncher-parent:0.1.0 (C:\Users\luisc\Downloads\olauncher\pom.xml) has 1 error
[ERROR] Child module C:\Users\luisc\Downloads\olauncher\olauncher\pom.xml of C:\Users\luisc\Downloads\olauncher\pom.xml does not exist
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/ProjectBuildingException

Process finished with exit code 1

And yes, I'm sure I cloned it correctly because I repeated the process 3 times.

[K4sum1]

How do you run .sh files on Windows? I've been trying to get a Linux VM up with openjdk6.

[K4sum1]

So I got it kinda working in Linux, but I need a version of fernflower compatible with Java 6 to get further.

[bigfoot547]

oh true. the decompilation output may be different, so the patches might not apply

[lousakura]

How do you run .sh files on Windows? I've been trying to get a Linux VM up with openjdk6.

I used Intellij IDEA to run them, don't know if I did it right tho

[K4sum1]

Where would I find a older compiled version of fernflower for Java 6?

[bigfoot547]

fesh0r/fernflower@35259c3 this commit seems like the commit before they began requiring java 8, seems ancient. Are you sure you can't use the java 8 version of fernflower? It may produce output compatible with java 6 with some modification

[K4sum1]

Is there a flag or something I can set to make it ignore the wrong Java version?

[bigfoot547]

you will still need to run fernflower with java 8, because a java 6 JRE can't run java 8 class files (the format probably changed)

[K4sum1]

So decompile with Java 8, then do the rest with Java 6?

[bigfoot547]

yes

[K4sum1]

I get this even with Java 8

administrator@administrator-VirtualBox:~/olauncher$ ./applyPatches.sh
Cloning into 'olauncher'...
done.
~/olauncher/olauncher ~/olauncher
From ../launcher

• [new branch] master -> upstream/master
  HEAD is now at e5a4852 Initial commit
  error: unknown option `no-gpg-sign'
  usage: git am [options] [(|)...]
  or: git am [options] (--continue | --skip | --abort)

  -i, --interactive run interactively
  -3, --3way allow fall back on 3way merging if needed
  -q, --quiet be quiet
  -s, --signoff add a Signed-off-by line to the commit message
  -u, --utf8 recode into utf8 (default)
  -k, --keep pass -k flag to git-mailinfo
  --keep-non-patch pass -b flag to git-mailinfo
  --keep-cr pass --keep-cr flag to git-mailsplit for mbox format
  --no-keep-cr do not pass --keep-cr flag to git-mailsplit independent of am.keepcr
  -c, --scissors strip everything before a scissors line
  --whitespace ... pass it through git-apply
  --ignore-space-change
  pass it through git-apply
  --ignore-whitespace pass it through git-apply
  --directory ... pass it through git-apply
  --exclude ... pass it through git-apply
  --include ... pass it through git-apply
  -C ... pass it through git-apply
  -p ... pass it through git-apply
  --patch-format ... format the patch(es) are in
  --reject pass it through git-apply
  --resolvemsg ... override error message when patch failure occurs
  --continue continue applying patches after resolving a conflict
  -r, --resolved synonyms for --continue
  --skip skip the current patch
  --abort restore the original branch and abort the patching operation.
  --committer-date-is-author-date
  lie about committer date
  --ignore-date use current timestamp for author date
  --rerere-autoupdate update the index with reused conflict resolution if possible

~/olauncher
Patches did not apply cleanly to olauncher. Please fix.

[K4sum1]

So I got further, but maven automatically set my java back to java 8, and I got this error

Downloading: http://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-clean-plugin/2.5/maven-clean-plugin-2.5.pom
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] olauncher-parent .................................. FAILURE [0.453s]
[INFO] olauncher ......................................... SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.526s
[INFO] Finished at: Wed Feb 22 12:48:12 CST 2023
[INFO] Final Memory: 5M/119M
[INFO] ------------------------------------------------------------------------
[ERROR] Plugin org.apache.maven.plugins:maven-clean-plugin:2.5 or one of its dependencies could not be resolved: Failed to read artifact descriptor for org.apache.maven.plugins:maven-clean-plugin:jar:2.5: Could not transfer artifact org.apache.maven.plugins:maven-clean-plugin:pom:2.5 from/to central (http://repo.maven.apache.org/maven2): Failed to transfer file: http://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-clean-plugin/2.5/maven-clean-plugin-2.5.pom. Return code is: 501 , ReasonPhrase:Not Implemented. -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginResolutionException
administrator@administrator-VirtualBox:~/olauncher$

[K4sum1]

New VM, copy paste is broken so I'm sending screenshots

Java 6

Java 7

[bigfoot547]

hmm maybe you can run maven with java 8 but set the source/target compatibility to 1.6. That will make it write java 6 class files with a java 8 jdk

[K4sum1]

How exactly would I do that?

[bigfoot547]

there should be a thing in the pom.xml

[K4sum1]

I found a target thing and set it to 1.6 but I get this when compiling.
long error.txt

[bigfoot547]

You may be able to downgrade or remove that plugin. All it does is generate the version string for the window title and other stuff. Not particularly necessary.

[K4sum1]

How exactly would I go about doing that?

[bigfoot547]

edit the pom.xml in the olauncher folder, the plugin configuration should be in there

[K4sum1]

I replaced it with 4.9.9 and I get this error now
other long error.txt

[bigfoot547]

Just get rid of the plugin, you don't need it. It's not worth the trouble it's causing you.

[K4sum1]

I did remove it and got a similar looking error, still have it up to send.
error 3.txt

[bigfoot547]

you need to set both source and target to 1.6 (you will likely have to modify the code to remove java8-only features that may have been used)

[K4sum1]

How do I know what's Java 8 or not?

[bigfoot547]

what doesn't compile when you set source and target to 1.6

[K4sum1]

very big error.txt

[bigfoot547]

you're going to have to rectify all of those by replacing them with constructs supported in java 6

[K4sum1]

I don't know how to do that.

[lousakura]

@bigfoot547 won't you be able to do it for us pleaseee?

[K4sum1]

🥺

bruh github pleading emoji sucks

[bigfoot547]

https://github.com/olauncher/olauncher/tree/java6 try this branch

NOTE: it is unlikely to work - a lot of the libraries are probably compiled for java 8. You may have to find java 6 versions of affected libraries. I cannot test this because I don't have a java 6 jdk.

[K4sum1]

If you're on Linux, this installs and just works on latest Ubuntu LTS (and probably forks too). Just select Java 6 (or 7) and get the .deb
https://www.azul.com/downloads/
I'll test it myself though to see what happens.

[K4sum1]

So it compiled without issue. I tried genredist, got an error, but the output jar without genredist works fine, at least with Java 8. For some reason I can't select Java 6 even though it was used to compile in my VM, so I will make a quick XP VM with Java 6 for testing.

[K4sum1]

Hmm

[bigfoot547]

yeah, I suspected that would be the case. You're going to have to find versions of the libraries used for java 6. It shouldn't be too hard, just not something I have the time to do right now.