Java Question desugar - fix the "invokedynamic requires" error

Some of the new Android libraries use Java 8 features. Android doesn't natively support those features so they must be removed (desugared) at some point.

When you wrap a library that includes such features you need to desugar the wrapped library. This is done with an Android tool named desugar.

It can be downloaded from here: www.b4x.com/android/files/Desugar_deploy.jar
This input of this tool is a jar file and the output is a "desugared" jar. You need to do it once and then use the desugared jar.

The latest version of ExoPlayer depends on 7 AAR packages. Desugaring these packages requires several steps:
- Extract the inner classes.jar from each AAR.
- Desugar it.
- Put it back or remove the original one.

To make things easier I wrote a small B4J app that does the following steps:
- Extracts all classes.jar and merges them to a single jar.
- The classes.jar files are removed from the AAR files.
- The merged jar is desugared.

Go over the code before you use it.
Note that it calls zip info: http://infozip.sourceforge.net/Zip.html#Release
zip.exe is available here: https://www.b4x.com/android/forum/t...r-merged-jar-is-not-a-val.111005/#post-693285
If the classes.jar depend on other libraries then you will need to add references by adding additional --bootclasspath_entry parameters.

This working fine for my next library! Thank you!

Erel said:

Some of the new Android libraries use Java 8 features. Android doesn't natively support those features so they must be removed (desugared) at some point.

When you wrap a library that includes such features you need to desugar the wrapped library. This is done with an Android tool named desugar.

It can be downloaded from here: www.b4x.com/android/files/Desugar_deploy.jar
This input of this tool is a jar file and the output is a "desugared" jar. You need to do it once and then use the desugared jar.

The latest version of ExoPlayer depends on 7 AAR packages. Desugaring these packages requires several steps:
- Extract the inner classes.jar from each AAR.
- Desugar it.
- Put it back or remove the original one.

To make things easier I wrote a small B4J app that does the following steps:
- Extracts all classes.jar and merges them to a single jar.
- The classes.jar files are removed from the AAR files.
- The merged jar is desugared.

Go over the code before you use it.
Note that it calls zip info: http://infozip.sourceforge.net/Zip.html#Release
If the classes.jar depend on other libraries then you will need to add references by adding additional --bootclasspath_entry parameters.

Click to expand...

I'm trying to run this project so that I can desugar around 4 .aar files and i keep getting the following error, I have changed all the necessary paths required for the Desugar_deploy.jar file, the folder where the .aar files are etc. what am i doing wrong?

Error parsing command line: While parsing option --input=Merged.jar: Merged.jar is not a valid path: it does not exist.

Click to expand...

Walter

The ExtractAndMergeClasses should create a merged.jar file in the temp folder. Do you see it?

Erel said:

The ExtractAndMergeClasses should create a merged.jar file in the temp folder. Do you see it?

Click to expand...

It wasn't creating the merger.jar file at first, i had downloaded a newer version of zip.exe, i found an older version of that exe file and it seems to work better now, however I keep getting errors about missing classes, i'm assuming these are classes that the library relies on.

Thanks,
Walter

walterf25 said:

however I keep getting errors about missing classes

Click to expand...

when running the desugar task?
Or when using the desugared files in your project?
In the last you need to included the merged.jar (#AdditionalJar) as it contains the desugared javacode of the AAR files.

When I run the b4J, after changing the paths, and pointing to the old zipe.exe, the app crashes when trying to extract from the .aar files. It never extracts classes.jar. I have tried to unzip them manually and there are no classes.jar files inside of the .aar files.

Randy Younger said:

I have tried to unzip them manually and there are no classes.jar files inside of the .aar files.

Click to expand...

This means that your AAR doesn't need to be desugared.