MacOS – Java class file could not be launched on startup

The problem is that you need to specify the class paths with the cp option to java and the library paths with the D option. The Minecraft launcher under /Applications handles this if you have a default install. If you want to run the default configuration from the commandline, just run something like the following with the memory values of your choosing:

java -Xmx2048M -Xms512M -jar \
/Applications/Minecraft.app/Contents/Resources/Java/MinecraftLauncher.jar

Here's an example of how I run Minecraft from the command-line for ad-hoc mode. I put the following in a script, name it and run it by name:

MCHOME="$HOME/Library/Application Support/minecraft/bin"
CP="$MCHOME/minecraft.jar:$MCHOME/lwjgl.jar:$MCHOME/lwjgl_util.jar:$MCHOME/jinput.jar"

java -Xmx2048M -Xms512M -cp "$CP" \
    -Djava.library.path="$MCHOME/natives" \
    net.minecraft.client.Minecraft

These message aren't being produced by Java. Launchd is part of OS X that manages scheduled jobs, amongst other things. The messages you are seeing here are launchd trying (unsuccessfully) to launch the Java Updater. It appears that the Java Updater is either partially or completely missing from your machine.

If you check the folder /Library/LaunchAgents/ on your Mac you should find a file called com.oracle.java.Java-Updater.plist. This file instructs launchd to run Java Updater once a week at a specific time.

If you need Java I would recommend uninstalling Java and then installing Java again from scratch. If you are using the Java Development Kit rather than the Java Runtime you can find uninstall instructions here and the install here.

Having said all this, I wouldn't expect this to cause kernel panics. This is simply a piece of software being repeatedly called to run and repeatedly failing. As klanomath mentioned you might want to check the kernel panic logs. You can find them in /Library/Logs/DiagnosticReports. They'll be called something like Kernel_DATE-TIME_COMPUTERNAME.panic.