From 1119f6c3cf421da2f2db92873efae8135c76b678 Mon Sep 17 00:00:00 2001
From: HsiangNianian <i@jyunko.cn>
Date: Fri, 16 Jan 2026 18:38:47 +0800
Subject: feat: enhance Java version management for Minecraft versions

Added functionality to determine and validate the required Java version for Minecraft versions, including checks for compatibility with older versions. Implemented event emissions for version installation and deletion, and updated the UI to reflect Java version requirements and installation status. Improved version metadata handling and added support for deleting versions.
---
 src-tauri/src/core/java.rs | 58 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

(limited to 'src-tauri/src/core/java.rs')

diff --git a/src-tauri/src/core/java.rs b/src-tauri/src/core/java.rs
index 1d57d21..0c7769b 100644
--- a/src-tauri/src/core/java.rs
+++ b/src-tauri/src/core/java.rs
@@ -881,6 +881,64 @@ pub fn get_recommended_java(required_major_version: Option<u64>) -> Option<JavaI
     }
 }
 
+/// Get compatible Java for a specific Minecraft version with upper bound
+/// For older Minecraft versions (1.13.x and below), we need Java 8 specifically
+/// as newer Java versions have compatibility issues with old Forge versions
+pub fn get_compatible_java(
+    app_handle: &AppHandle,
+    required_major_version: Option<u64>,
+    max_major_version: Option<u32>,
+) -> Option<JavaInstallation> {
+    let installations = detect_all_java_installations(app_handle);
+
+    if let Some(max_version) = max_major_version {
+        // Find Java version within the acceptable range
+        installations.into_iter().find(|java| {
+            let major = parse_java_version(&java.version);
+            let meets_min = if let Some(required) = required_major_version {
+                major >= required as u32
+            } else {
+                true
+            };
+            meets_min && major <= max_version
+        })
+    } else if let Some(required) = required_major_version {
+        // Find exact match or higher (no upper bound)
+        installations.into_iter().find(|java| {
+            let major = parse_java_version(&java.version);
+            major >= required as u32
+        })
+    } else {
+        // Return newest
+        installations.into_iter().next()
+    }
+}
+
+/// Check if a Java installation is compatible with the required version range
+pub fn is_java_compatible(
+    java_path: &str,
+    required_major_version: Option<u64>,
+    max_major_version: Option<u32>,
+) -> bool {
+    let java_path_buf = PathBuf::from(java_path);
+    if let Some(java) = check_java_installation(&java_path_buf) {
+        let major = parse_java_version(&java.version);
+        let meets_min = if let Some(required) = required_major_version {
+            major >= required as u32
+        } else {
+            true
+        };
+        let meets_max = if let Some(max_version) = max_major_version {
+            major <= max_version
+        } else {
+            true
+        };
+        meets_min && meets_max
+    } else {
+        false
+    }
+}
+
 /// Detect all installed Java versions (including system installations and DropOut downloads)
 pub fn detect_all_java_installations(app_handle: &AppHandle) -> Vec<JavaInstallation> {
     let mut installations = detect_java_installations();
-- 
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