Incompatible Java versions?

[algebravic]

I just did a git clone of mallet. At first I had a problem with a mismatch since I'm running on mac OS, and the default java there is almost 8 years old! I then used homebrew to install openjdk and was careful to update environment variables so that the programs and libraries would be found before the defalt MacOS versions. I'm actually using mallet as called by the program topics. The latter extracts a bunch of text files from pdf files and puts them in a subdirectory. Any suggestions as to how to fix this? Below is an example of the problem.

./mallet/bin/mallet import-dir --input txt
Labels = 
   txt
Exception in thread "main" java.lang.NoClassDefFoundError: com/carrotsearch/hppc/ObjectIntHashMap
        at cc.mallet.types.Alphabet.<init>(Alphabet.java:61)
        at cc.mallet.types.Alphabet.<init>(Alphabet.java:77)
        at cc.mallet.types.LabelAlphabet.<init>(LabelAlphabet.java:25)
        at cc.mallet.pipe.Target2Label.<init>(Target2Label.java:35)
        at cc.mallet.classify.tui.Text2Vectors.main(Text2Vectors.java:167)
Caused by: java.lang.ClassNotFoundException: com.carrotsearch.hppc.ObjectIntHashMap
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:490)
        ... 5 more

Here's the versions of the various software I'm using:

java --version
openjdk 25.0.1 2025-10-21
OpenJDK Runtime Environment Homebrew (build 25.0.1)
OpenJDK 64-Bit Server VM Homebrew (build 25.0.1, mixed mode, sharing)

mvn --version
Apache Maven 3.9.12 (848fbb4bf2d427b72bdb2471c22fced7ebd9a7a1)
Maven home: /opt/homebrew/Cellar/maven/3.9.12/libexec
Java version: 25.0.1, vendor: Homebrew, runtime: /opt/homebrew/Cellar/openjdk/25.0.1/libexec/openjdk.jdk/Contents/Home
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "26.2", arch: "aarch64", family: "mac"

[mimno]

Thanks for using Mallet! The recently updated version switched to a maven-based installation. Running "compile" doesn't copy the dependencies to the default classpath for the bin/mallet script.

Running mvn package should fix this. Could you give it a try?

[algebravic]

Thanks. So there were two problems. I found that mvn wasn’t present on my Mac, so I installed the maven package with homebrew. When I did mvn package it said that all tests had passed, but I later got the error I described. I then noticed that the standard java on the Mac dated from 2018! I had installed OpenJdk but it wasn’t put on the right paths in the environment. I fixed that using the module package. I then did mvn clean and then mvn package, and now it works ok. Perhaps you should add a warning in the README for Mac users about the Java version problem.

…

On Sat, Jan 10, 2026 at 13:44 mimno ***@***.***> wrote: *mimno* left a comment (mimno/Mallet#215) <#215 (comment)> Thanks for using Mallet! The recently updated version switched to a maven-based installation. Running "compile" doesn't copy the dependencies to the default classpath for the bin/mallet script. Running mvn package should fix this. Could you give it a try? — Reply to this email directly, view it on GitHub <#215 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAHBBJQZ7263LIJEFRSF6VL4GFXFXAVCNFSM6AAAAACRJEAVBWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTOMZTGU4DKOJTGU> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[mimno]

I had an update ready for the README, I just wanted to make sure that was everything. Pushed now. Thanks again for taking the time to ask! On Sat, Jan 10, 2026 at 5:06 PM Victor S. Miller ***@***.***> wrote:

…

*algebravic* left a comment (mimno/Mallet#215) <#215 (comment)> Thanks. So there were two problems. I found that mvn wasn’t present on my Mac, so I installed the maven package with homebrew. When I did mvn package it said that all tests had passed, but I later got the error I described. I then noticed that the standard java on the Mac dated from 2018! I had installed OpenJdk but it wasn’t put on the right paths in the environment. I fixed that using the module package. I then did mvn clean and then mvn package, and now it works ok. Perhaps you should add a warning in the README for Mac users about the Java version problem. On Sat, Jan 10, 2026 at 13:44 mimno ***@***.***> wrote: > *mimno* left a comment (mimno/Mallet#215) > <#215 (comment)> > > Thanks for using Mallet! The recently updated version switched to a > maven-based installation. Running "compile" doesn't copy the dependencies > to the default classpath for the bin/mallet script. > > Running mvn package should fix this. Could you give it a try? > > — > Reply to this email directly, view it on GitHub > <#215 (comment)>, or > unsubscribe > < https://github.com/notifications/unsubscribe-auth/AAHBBJQZ7263LIJEFRSF6VL4GFXFXAVCNFSM6AAAAACRJEAVBWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTOMZTGU4DKOJTGU> > . > You are receiving this because you authored the thread.Message ID: > ***@***.***> > — Reply to this email directly, view it on GitHub <#215 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AARPWOSTGDPNBUOWL22H36L4GFZWZAVCNFSM6AAAAACRJEAVBWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTOMZTGYYDIMZTHA> . You are receiving this because you commented.Message ID: ***@***.***>

[raghu298]

@algebravic @mimno
Do we have documentation available for upgrading from version 2.0.8 to 2.1.0?
Based on my understanding, the upgrade would require the following steps:
Regenerate serialized objects: Remove all existing serialized MALLET models, feature alphabets, and data files, and recreate them using version 2.1.0.

Update test data: Any test cases that rely on pre-serialized MALLET objects must be updated to regenerate those objects with the new version.

[mimno]

I used Claude to develop a cross-walk from 2.0.8 data files to 2.1.0: https://github.com/mimno/MalletJSON If you get a chance to try it, let me know what you think. It doesn't support models yet, but the model file for a topic model should be fully recoverable from the input instance list and the gzipped state file. The serialization-breaking switch to hppc from trove was on github in 2019 but not maven central. I tried a JSON-based cross-walk at the time, this was a lot easier.

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On Mon, Jan 12, 2026 at 2:32 AM raghu298 ***@***.***> wrote: *raghu298* left a comment (mimno/Mallet#215) <#215 (comment)> @algebravic <https://github.com/algebravic> @mimno <https://github.com/mimno> Can we have a documenttaion how to upgrade form 2.0.8 to 2.1.0 version? I think we need to below steps Regenerate serialized objects: Delete all saved MALLET models, feature alphabets, and serialized data files, then regenerate them using version 2.1.0 Update test data: Any test cases using pre-serialized MALLET objects must recreate those objects with the new version — Reply to this email directly, view it on GitHub <#215 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AARPWOVHVHPKE6QMVTTDQKT4GNEXJAVCNFSM6AAAAACRJEAVBWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTOMZXGIYTINRRGU> . You are receiving this because you were mentioned.Message ID: ***@***.***>