[SOLVED] Java app won't run

Janus84 · 11-26-2019, 02:48 AM

Installed and configured Java as per instructions on their website.
Downloaded and unpacked Ubiquiti discovery tool .jar.

I get:

Code:

$ java -jar "ubnt-discovery-v2.5.1.jar"
Exception in thread "main" java.lang.ClassFormatError: Illegal field name "this.super" in class com/OoOO/super/A/o0oO
        at java.base/java.lang.ClassLoader.defineClass1(Native Method)
        at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
        at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
        at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:800)
        at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:698)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:621)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:579)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
        at com.ubnt.discovery.Main.<clinit>(Unknown Source)
$

Thanks!

pan64 · 11-26-2019, 03:40 AM

no, this is not a permission error (I guess). Probably the command you executed is incomplete, or the environment was not set properly, a [jar] file is missing or ???

Janus84 · 12-13-2019, 06:09 PM

I have re-installed Java, re-downloaded the discovery tool and there is the same error.
Looking up the first line of this error returns the same question in some other language on some other forum with zero answers.

Any ideas please?

Code:

$ java -jar ubnt.jar
Exception in thread "main" java.lang.ClassFormatError: Illegal field name "this.super" in class com/OoOO/super/A/o0oO
        at java.base/java.lang.ClassLoader.defineClass1(Native Method)
        at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
        at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151)
        at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:821)
        at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:719)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:642)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:600)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
        at com.ubnt.discovery.Main.<clinit>(Unknown Source)

boughtonp · 12-13-2019, 06:45 PM

Quote:

Originally Posted by Janus84

I have re-installed Java, re-downloaded the discovery tool and there is the same error.
Looking up the first line of this error returns the same question in some other language on some other forum with zero answers.

I searched in DuckDuckGo and it also returned a Reddit thread containing:

Quote:

I found a solution to this problem.

sudo apt remove openjdk-*
wget https://raw.githubusercontent.com/ro...6/master/j6.sh && bash j6.sh
finely reboot or logout

I don't recommend blindly running scripts in that fashion, but inspecting the file shows that (amongst other things) it installs a specific version of Java (6u45), so maybe the issue is Ubiquiti only runs correctly for that version of Java?

Sounds like an issue to be raised with whoever produces Ubiquiti.

pan64 · 12-14-2019, 04:27 AM

actually you gave no usable information. Also repeating the same error message does not help to go further. We have no idea what have you downloaded from where and how did you try to install (on what os). So you need to check if the java version is compatible with the version of ubiquiti you have. Also you may need to check other environment settings (like CLASSPATH). You also may need to use jdk instead of openjdk.

Janus84 · 04-07-2020, 06:20 PM

The UBNT apps require Java 8.

Install OpenJDK 8:

Code:

sudo apt-get install openjdk-8-jre-headless -y

Check if you have the Java 8 installed:

Code:

java -version

If you keeping other versions of Java and only adding Java 8, you will need to switch between default versions. This is described elsewhere.

If you run .jar file and get

Exception in thread "main" java.awt.AWTError: Assistive Technology not found: org.GNOME.Accessibility.AtkWrapper

Simply disable assistive technologies:

Code:

sudo nano /etc/java-8-openjdk/accessibility.properties

Comment out the following line:

#assistive_technologies=org.GNOME.Accessibility.AtkWrapper

Should work now