Command-line java build infra

.gitignore

@@ -7,5 +7,6 @@ server/test1_latency
 server/test3_latency
 depend.mk
 java/out
+java/build
 *.iml
 .idea

java/build.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0"?>
+<project name="Hop" default="jar">
+  <path id="javac.classpath">
+    <fileset dir="lib">
+      <include name="**/*.jar"/>
+    </fileset>
+  </path>
+
+  <target name="build">
+    <mkdir dir="build/classes"/>
+    <javac destdir="build/classes" classpathref="javac.classpath" debug="true">
+      <src path="hop"/>
+    </javac>
+  </target>
+
+  <target name="jar" depends="build">
+    <mkdir dir="build/lib"/>
+    <jar destfile="build/lib/hop.jar" basedir="build/classes" />
+  </target>
+
+  <target name="clean">
+    <delete dir="build"/>
+  </target>
+</project>