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cire

•Created by cire on 10/17/2024 in #java-help

Java agent throws UnsupportedClassVersionError when Instrumentation#retransformClasses is called.

I need to dump who invokes a setCancelled(boolean cancelled) method in a running jar (Spigot 1.8). I decided to do this via dumping the caller using StackWalker by using a javaagent to add a method call which dumps the caller, the item field which is of type org.bukkit.inventory.ItemStack, & the cancelled argument. The only issue currently, is that when i call retransformClasses the whole thing comes burning down. Target class: org.bukkit.event.player.PlayerInteractEvent The agent is compiled under Java 17.0.12 the JVM is 17.0.12 The spigot jar is java 8 (i think) Ran via the -javaagent command line option

86 replies

JCHJava Community | Help. Code. Learn.

•Created by cire on 4/13/2024 in #java-help

Can not determine cause of failure

Hello! I was practicing on some past codeforces problems (https://codeforces.com/gym/102951/problem/C), and I just can't seem to get this one. I know my code probably isn't the typical way of doing this, but I can't seem to figure out why it fails on test 4. Code: https://pastebin.com/Hdian9Ak

8 replies

JCHJava Community | Help. Code. Learn.

•Created by cire on 6/1/2023 in #java-help

Difference between <?> and <L>

I'm making a listener system, and I was wondering what the difference between

public void register(Class<? extends Listener> listener)

public void register(Class<? extends Listener> listener)

and

public void register(Class<L extends listener> listener)

public void register(Class<L extends listener> listener)

Is either one better than the other, and if so, which?

47 replies

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