core: langs: fix java multi-class

packages/hydrooj/package.json

@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "3.2.41",
+    "version": "3.2.42",
     "bin": "bin/hydrooj.js",
     "main": "src/loader",
     "module": "src/loader",

packages/hydrooj/setting.yaml

@@ -58,10 +58,10 @@ langs:
       highlight: pascal
       display: Pascal
     java:
-      compile: /usr/bin/javac -d ${dir} -encoding utf8 ./Main.java
+      compile: /usr/bin/bash -c "javac -d ${dir} -encoding utf8 ./Main.java && jar cvf Main.jar *.class >/dev/null"
       code_file: Main.java
-      target: Main.class
-      execute: /usr/bin/java Main
+      target: Main.jar
+      execute: /usr/bin/java -cp Main.jar Main
       time_limit_rate: 2
       highlight: java astyle-java
       monaco: java