I collect magic here for an onscreen movie. (Java Grist) The plan is to modify the physics C code to emit binary coordinates of line segment endpoints into a pipe from which a Java program would plot them.
Java, Java library 
javac Echo.java
echo "don't do that" | java -cp . Echo
yields: 
Enter the message : You entered : don't do that
  1. The above code reads characters form standard in—a pipe here.
  2. Java code that reads binary numbers from a file.
  3. Java code that makes moving images on screen.
  4. Write binary to pipe
From #1 we need to start from System.in. Its type is InputStream. It would seem from #2 that we need stdin as a FileInputStream, but that seems to be wrong! 

javac Show.java
gcc wbp.c -Wmost
./a.out | java -cp . Show
=> 0 0 10 0 40 0 90 0 160 0 250 0 104 1 234 1 128 2 42 3
and 
./a.out > xxcc
od -t x1 xxcc
=> 
0000000    00  00  0a  00  28  00  5a  00  a0  00  fa  00  68  01  ea  01
0000020    80  02  2a  03                                                
0000024
Reading into a buffer works but is ugly and delivers signed bytes!

First class double buffering in Java seems to lead to the BufferStrategy class which is one of those classes whose contract fails to tell me whether I am the party of the first part or the second part. It clearly fails to isolate you from hardware details. I will try to avoid double buffering for now.

Now 

gcc a.c -Wmost -std=c99 -fnested-functions
./a.out > pipe
javac Mv.java
java -cp . Main < pipe
makes a still.