feat(legacy): check Java version at start (#5550)

src/main/java/net/ccbluex/liquidbounce/LiquidBounce.kt

@@ -46,6 +46,7 @@ import net.ccbluex.liquidbounce.utils.client.ClassUtils.hasForge
 import net.ccbluex.liquidbounce.utils.client.ClientUtils.LOGGER
 import net.ccbluex.liquidbounce.utils.client.ClientUtils.disableFastRender
 import net.ccbluex.liquidbounce.utils.client.PacketUtils
+import net.ccbluex.liquidbounce.utils.client.checkJavaVersion
 import net.ccbluex.liquidbounce.utils.inventory.InventoryManager
 import net.ccbluex.liquidbounce.utils.inventory.InventoryUtils
 import net.ccbluex.liquidbounce.utils.inventory.SilentHotbar
@@ -117,6 +118,9 @@ object LiquidBounce {
      * Start IO tasks
      */
     fun preload(): Future<*> {
+
+        checkJavaVersion()
+
         // Change theme of Swing
         UIManager.setLookAndFeel(FlatMacLightLaf())
 

src/main/java/net/ccbluex/liquidbounce/utils/client/JavaVersion.kt

@@ -0,0 +1,68 @@
+/*
+ * LiquidBounce Hacked Client
+ * A free open source mixin-based injection hacked client for Minecraft using Minecraft Forge.
+ * https://github.com/CCBlueX/LiquidBounce/
+ */
+package net.ccbluex.liquidbounce.utils.client
+
+import kotlinx.coroutines.launch
+import net.ccbluex.liquidbounce.LiquidBounce
+import net.ccbluex.liquidbounce.utils.io.MiscUtils
+import net.ccbluex.liquidbounce.utils.kotlin.SharedScopes
+import javax.swing.JOptionPane
+
+private const val DOWNLOAD_PAGE = "https://www.java.com/download/manual.jsp"
+
+/**
+ * Check if the client is run on a proper JVM.
+ */
+fun checkJavaVersion() {
+    val javaVersion = System.getProperty("java.version")
+
+    val regex = Regex("""(\d+)(?:\.(\d+))?(?:\.(\d+))?_?(\d+)?""")
+    val matchResult = regex.matchEntire(javaVersion)
+
+    if (matchResult != null) {
+        val (major, minor, patch, update) = matchResult.destructured
+
+        when {
+            // <= Java 8
+            major == "1" -> when {
+                // < Java 8, crash
+                minor.toInt() < 8 -> {
+                    MiscUtils.showURL(DOWNLOAD_PAGE)
+                    error("You should start ${LiquidBounce.CLIENT_NAME} with Java 8! Get it from $DOWNLOAD_PAGE")
+                }
+                // < Java 8u100, warn
+                update.toInt() < 100 -> {
+                    SharedScopes.IO.launch {
+                        MiscUtils.showMessageDialog(
+                            title = "Warning",
+                            message = "You are using an outdated version of Java 8 ($javaVersion).\n"
+                                    + "This might cause unexpected bugs.\n"
+                                    + "Please update it to 8u101+ or get a new one from $DOWNLOAD_PAGE.",
+                            JOptionPane.WARNING_MESSAGE
+                        )
+                        MiscUtils.showURL(DOWNLOAD_PAGE)
+                    }
+                }
+            }
+            // > Java 8
+            major.toInt() > 8 -> {
+                SharedScopes.IO.launch {
+                    MiscUtils.showMessageDialog(
+                        title = "Warning",
+                        message = "This version of ${LiquidBounce.CLIENT_NAME} is designed for Java 8 environment.\n"
+                                + "Higher versions of Java might cause bug or crash.\n"
+                                + "You can get JRE 8 from $DOWNLOAD_PAGE.",
+                        JOptionPane.WARNING_MESSAGE
+                    )
+                    MiscUtils.showURL(DOWNLOAD_PAGE)
+                }
+            }
+        }
+    } else {
+        // ???
+        ClientUtils.LOGGER.error("Failed to parse Java version $javaVersion")
+    }
+}