Add some information about Java bindings. (rmind#10)

README.md

@@ -7,7 +7,7 @@ The implementation is written in C99 and is distributed under the
 2-clause BSD license.
 
 Additionally, bindings are available for **Lua** and **Java**.
-There is a specification to build an RPM package.
+Specifications to build RPM and DEB packages are also provided.
 
 ## API
 
@@ -49,7 +49,9 @@ There is a specification to build an RPM package.
   provide at least 4 or 16 bytes (depending on the address family).  Returns
   zero on success and -1 on failure.
 
-## Lua example
+## Examples
+
+### Lua
 
 ```lua
 local lpm = require("lpm")
@@ -67,6 +69,12 @@ local ret = acl:lookup(lpm.tobin("10.0.0.100"))
 print(ret.val)
 ```
 
+### Java
+
+See [README](src/jni) how to build the JAR and the
+[test case](src/jni/org/netbsd/liblpm/LPMTest.java) as example
+how to use the Java API
+
 ## Packages
 
 Just build the package, install it and link the library using the

src/jni/Makefile

@@ -2,9 +2,11 @@
 # This file is in the Public Domain.
 #
 
-CFLAGS=		-std=gnu99 -O2 -g -W -Wextra -Werror -D_BSD_SOURCE
-CFLAGS+=	-Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith
-CFLAGS+=	-Wshadow -Wcast-qual -Wwrite-strings
+CFLAGS+=	-std=c99 -O2 -g -Wall -Wextra -Werror
+CFLAGS+=	-D_POSIX_C_SOURCE=200809L
+CFLAGS+=	-D_GNU_SOURCE -D_DEFAULT_SOURCE
+
+CFLAGS+=	-Wno-unused-parameter
 
 ifeq ($(MAKECMDGOALS),tests)
 DEBUG=		1

src/jni/README.md

@@ -0,0 +1,17 @@
+# LPM library Java bindings
+
+## Building
+
+The below is an example of building on Debian 10.  Set the `JAVA_HOME`
+according to your JDK version and system.
+
+```shell
+$ uname -srv
+Linux 4.9.0-9-amd64 #1 SMP Debian 4.9.168-1 (2019-04-12)
+$ sudo apt-get install openjdk-8-jre-headless openjdk-8-jdk-headless
+...
+$ cd liblpm/src/jni
+$ JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64 make test
+```
+
+This will produce the `liblpm.jar` file.  Use it in your project.