Lino and Java

Note

This document is obsolete because Java is no longer supported in browsers and Lino no longer needs Java.

Some Lino applications (e.g. Lino Welfare) uses plugins that require two Java applets:

  • lino.modlib.beid is for reading Belgian eId cards

  • lino.modlib.davlink is to provide possibility to edit printable documents on a server with WebDAV.

You can easily disable these functionalities by setting use_java to False in your lino_local.py.

Java cheat sheet

When using Java applets, you might encounter problems due to Java's security system.

Note

Warning: This is just a cheat sheet! Don't use it without understanding what a command does.

update-java-alternatives

$ sudo update-alternatives --config java

$ update-java-alternatives -l
java-1.6.0-openjdk-i386 1061 /usr/lib/jvm/java-1.6.0-openjdk-i386
java-1.7.0-openjdk-i386 1071 /usr/lib/jvm/java-1.7.0-openjdk-i386
java-7-oracle 1073 /usr/lib/jvm/java-7-oracle

$ sudo update-java-alternatives -s java-1.7.0-openjdk-i386
update-alternatives: error: no alternatives for apt

How can I see which Java version I am using?

Simply run it:

$ java -version

OpenJDK Java will answer:

java version "1.7.0_25"
OpenJDK Runtime Environment (IcedTea 2.3.10) (7u25-2.3.10-1ubuntu0.13.04.2)
OpenJDK Server VM (build 23.7-b01, mixed mode)

Oracle Java will answer:

java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) Server VM (build 24.45-b08, mixed mode)

How to generate a self-signed key

$ keytool -genkey
$ keytool -selfcert
$ keytool -list

How to get rid of "update-alternatives: error: no alternatives for apt"

This error can have multiple explanations. On 2014-02-11 I solved this by removing and reinstalling Java...

How to flush the Java cache?

  • On Debian/Ubuntu, simply do:

    $ javaws -Xclearcache
    

    You can also launch the IcedTea Web Control Panel and inspect your cache, disable caching alltogether and other thing. But I didn't manage to delete individual entries (Ubuntu 13.10).