Runtime.exec( ) is hanging....

Question

i have an app the uses Runtime to fire an [.exe]. the [.exe] is suppose to load a file. i see from the log window that the [.exe] kicked off...but it just hangs when it's suppose to process the file.
below is my source...please help:
public class TestRuntime {
public TestRuntime() {
runBatch();
private void runBatch() {
try {
System.out.println("running...");
Runtime run = Runtime.getRuntime();
Process batch = run.exec("posloader.exe FXOpt c:\\all_test.pos");
BufferedReader reader = new BufferedReader(new InputStreamReader(batch.getInputStream()));
String line = null;
while((line = reader.readLine()) != null) {
System.out.println(" " + line);
int value = batch.waitFor();
if(value == 0) {
System.out.println(" Successful load of file!");
} else {
System.out.println(" Unsuccessful load of file - Error code: " + value);
batch.destroy(); //destroy process
batch = null;
} catch(InterruptedException ie) {
System.out.println(ie.toString());
} catch(IOException ioe) {
System.out.println(ioe.toString());
public static void main(String args[]) {
new TestRuntime();
System.exit(0);
thank you in advance...

Answer 1

The io from a process (exec) is buffered. If the buffer fills then the thread that has the buffer blocks.
And if you only have a single thread then your entire application blocks.
The solution is to add at least one thread for io. You could even add one for each stream (error and standard) although you don't seem to be using error.