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Java: use other program's static method's output in my program

I need to read a byte[] produced by another java program I wrote. As known, main in java can only return a void. Does this mean I need to write a program with a static method with the return type byte[] ? If yes, how can I then run this method in my program and save it's return value in my programm? this is what I have in my program:

ProcessBuilder pb = new ProcessBuilder("java.exe","viewer.java","pathToViewer.java");
Process process = pb.start();
InputStream is = process.getInputStream();
byte[] bytes = IOUtils.toByteArray(is);

What is the right way?

Solution

  • No, you can't communicate return values across JVM instances. You must devise and implement a specific protocol that will pass the data. One simple option you have is writing to System.out in the subprocess, which will push the data into your is, so your bytes will end up containing what the subprocess wrote.