From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Nassim Jahnke <nassim@njahnke.dev>
Date: Wed, 16 Mar 2022 13:58:16 +0100
Subject: [PATCH] Improve java version check

Co-Authored-By: MiniDigger <admin@benndorf.dev>

diff --git a/src/main/java/org/bukkit/craftbukkit/Main.java b/src/main/java/org/bukkit/craftbukkit/Main.java
index 446403f73fb1b5687d587889e6f32dce464d05a6..ed167d0d399924d54d9ff99c10ab8ee093efc149 100644
--- a/src/main/java/org/bukkit/craftbukkit/Main.java
+++ b/src/main/java/org/bukkit/craftbukkit/Main.java
@@ -203,11 +203,20 @@ public class Main {
                 return;
             }
 
-            float javaVersion = Float.parseFloat(System.getProperty("java.class.version"));
-            if (javaVersion > 66.0) {
-                System.err.println("Unsupported Java detected (" + javaVersion + "). Only up to Java 22 is supported.");
-                return;
+            // Paper start - Improve java version check
+            boolean skip = Boolean.getBoolean("Paper.IgnoreJavaVersion");
+            String javaVersionName = System.getProperty("java.version");
+            // J2SE SDK/JRE Version String Naming Convention
+            boolean isPreRelease = javaVersionName.contains("-");
+            if (isPreRelease) {
+                if (!skip) {
+                    System.err.println("Unsupported Java detected (" + javaVersionName + "). You are running an unsupported, non official, version. Only general availability versions of Java are supported. Please update your Java version. See https://docs.papermc.io/paper/faq#unsupported-java-detected-what-do-i-do for more information.");
+                    return;
+                }
+
+                System.err.println("Unsupported Java detected ("+ javaVersionName + "), but the check was skipped. Proceed with caution! ");
             }
+            // Paper end - Improve java version check
 
             try {
                 // Paper start - Handled by TerminalConsoleAppender