I am getting an exe-File, which I have to execute using Java (Version 6) on Windows Server 2008 R2. Now there is s problem I do not really understand. When executing the file with the commandline
"C:\test.exe param1 param2"
it works correctly, but when I execute the file with
Process proc = Runtime.getRuntime().exec("C:\\test.exe param1 param2");
proc.waitFor();
I can see the test.exe in the windows task manager and it starts running (it creates a log which states that), but then it simply doesn't do anything anymore. The test.exe endlessly runs with 0% and I have to kill the process manually. After doing so the java-program continues and
proc.exitValue()
is "1", therefore java recognizes that I have killed the process. I also tried writing the commandline in a batchfile and executing it with .exec() but it didn't change anything.
What really confuses me, is that it runs perfectly via windows command-line, but does not via .exec(). Does anyone have an idea what might cause such a problem? Or is it more likely that the test.exe is causing the problem?
In best regards
Edit: Wrote down the wrong path in .exec
Since your program procudes a lot of output, my hypothesis is that it is stuck trying to write to the standard output (which is a pipe under Linux, don't know for Windows).
Try this:
final byte[] devnull = new byte[1024];
final ProcessBuilder builder = new ProcessBuilder("C:\\test.exe", "param1", "param2")
.redirectErrorStream(true);
final Process p = builder.start();
final InputStream stdout = process.getInputStream();
// Purge stdout
while (stdout.read[devnull] != -1);
// Grab the process' exit code here
"C:\test.exe param1 param2"
You have a tab in there. Try this:
"C:\\test.exe param1 param2"
If the process produces any output on either stdout or stderr you need to consume it. Otherwise it can block.
As fge pointed out in https://stackoverflow.com/a/21903969 , it is important to consume all the output that is produced by the process - not only on Linux, but also on Windows, and not only the standard output, but also the possible errors.
The general pattern for this could look like this:
private static void runCommand(String command) throws IOException
{
Process process = Runtime.getRuntime().exec(command);
String errorMessage =
new String(toByteArray(process.getErrorStream()));
String outputMessage =
new String(toByteArray(process.getInputStream()));
int exitValue = 0;
try
{
exitValue = process.waitFor();
}
catch (InterruptedException e)
{
Thread.currentThread().interrupt();
}
System.out.println("Output message: "+outputMessage);
System.out.println("Error message: "+errorMessage);
System.out.println("Exit value: "+exitValue);
}
private static byte[] toByteArray(
InputStream inputStream) throws IOException
{
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte buffer[] = new byte[8192];
while (true)
{
int read = inputStream.read(buffer);
if (read == -1)
{
break;
}
baos.write(buffer, 0, read);
}
return baos.toByteArray();
}
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