diff --git a/java_gen/pre-written/src/main/java/org/openflow/protocol/match/MatchFields.java b/java_gen/pre-written/src/main/java/org/openflow/protocol/match/MatchFields.java
new file mode 100644
index 0000000..21043f2
--- /dev/null
+++ b/java_gen/pre-written/src/main/java/org/openflow/protocol/match/MatchFields.java
@@ -0,0 +1,33 @@
+package org.openflow.protocol.match;
+
+public enum MatchFields {
+    IN_PORT,
+    PHYSICAL_PORT,
+    METADATA,
+    ETH_DST,
+    ETH_SRC,
+    ETH_TYPE,
+    VLAN_VID,
+    VLAN_PCP,
+    IP_DSCP,
+    IP_ECN,
+    IP_PROTO,
+    IPV4_SRC,
+    IPV4_DST,
+    TCP_SRC,
+    TCP_DST,
+    UDP_SRC,
+    UDP_DST,
+    SCTP_SRC,
+    SCTP_DST,
+    ICMPV4_TYPE,
+    ICMPV4_CODE,
+    ARP_OP,
+    ARP_SPA,
+    ARP_TPA,
+    ARP_SHA,
+    ARP_THA,
+    IPV6_SRC,
+    IPV6_DST,
+    IPV6_FLOWLABEL,
+}