Add short example of Java interface.

samples/java_interface/short_example.m:
    A Java version of the short example.

samples/java_interface/README.md:
    Add an entry for the new example.

samples/c_interface/README.md:
samples/csharp_interface/README.md:
    Fix wording.

samples/c_interface/README.md

@@ -4,7 +4,7 @@ Mercury C Interface Examples
 This directory contains some examples of mixed Mercury/C/C++/Fortran programs
 using the foreign language interface.
 
-* [short_example.m](short_example.m) -- A short example of a Mercury code
+* [short_example.m](short_example.m) -- A short example of Mercury code
   calling C code.
 
 * [mercury_calls_c](mercury_calls_c) -- A detailed example of Mercury code

samples/csharp_interface/README.md

@@ -4,7 +4,7 @@ Mercury C# Interface Examples
 This directory contains some examples of mixed Mercury/C# programs using the
 foreign language interface.
 
-* [short_example.m](short_example.m) -- A short example of a Mercury code
+* [short_example.m](short_example.m) -- A short example of Mercury code
   calling C# code.
 
 * [standalone_csharp](standalone_csharp) -- An example of how to call a Mercury

samples/java_interface/README.md

@@ -4,6 +4,9 @@ Mercury Java Interface Examples
 This directory contains some examples of mixed Mercury/Java programs using
 the foreign language interface.
 
+* [short_example.m](short_example.m) -- A short example of Mercury code
+  calling Java code.
+
 * [mercury_calls_java](mercury_calls_java) -- A detailed example of Mercury
   code calling Java code.
 

samples/java_interface/short_example.m

@@ -0,0 +1,23 @@
+% This is a simple example of using the foreign language interface to call the
+% Java method System.out.println().
+
+% This source file is hereby placed in the public domain.
+
+:- module short_example.
+:- interface.
+:- import_module io.
+
+:- pred main(io::di, io::uo) is det.
+
+:- implementation.
+
+main(!IO) :-
+    java_write_line("Hello, world", !IO).
+
+:- pred java_write_line(string::in, io::di, io::uo) is det.
+:- pragma foreign_proc("JAva",
+    java_write_line(S::in, _IO0::di, _IO::uo),
+    [promise_pure, will_not_call_mercury],
+"
+    System.out.println(S);
+").