Run External Programms in Java

Question

I want that my Java Programm 3 external Programms runs. But they should be run NOT in parallel. Programm 1 should output a File, this File is the Input for Programm 2, The output for Programm 2 should be the Input for Programm 3. And the Java Programm should NOT terminate, when the external programms terminate: This is my code but it does not work. Can anyone pls help me!

boolean var = true;
ProcessBuilder processBuilder = new ProcessBuilder("cmd", "/c",
 "start", "C:\\Users\\Rosina\\Desktop\\Riss\\winlibs\\riss3g64", "C:\\Users\\Rosina\\Desktop\\out.cnf", "C:\\Users\\Rosina\\Desktop\\pruv.txt" );
 Process process = processBuilder.start(); 
 while(program.exists() && var) {
 ProcessBuilder processBuilder3 = new ProcessBuilder("cmd", "/c",
 "start", "C:\\Users\\Rosina\\Desktop\\Riss\\winlibs\\riss3g64", "C:\\Users\\Rosina\\Desktop\\out1.cnf", "C:\\Users\\Rosina\\Desktop\\hahaaaaaaaaaaaaaaafffa2.txt" );
 Process process2 = processBuilder3.start();
 var = false;
 } 

If Programm 1 has not produce the output, the file program does not exist, and Programm 2 can not start execution...where is my mistake...the code does not work...

• hmjd: Process.waitFor() will help you achieve sequential execution of the programs.

Answer 1

You need to wait on the process you launched to finish. You can block the current thread of execution until the process finishes with

process.waitFor()