Can't execute javac or other command line applications in Java using ProcessBuilder under Windows 7

Question

I'm trying to execute javac from Java using ProcessBuilder but i get no output and nothing happens. I tried reading the input stream (as there is a bug where the process hangs if i don't read it) but still no results. I originally passed all required parameters to javac but it was not working, so i simplified it down to just javac (which should print the help message).

i tried running "C:\Windows\System32\cmd.exe /c C:\\"Program Files\"\Java\jdk1.6.0_23\bin\javac.exe" "C:\\"Program Files\"\Java\jdk1.6.0_23\bin\javac.exe" and surrounding the entire path to javac with double quotes but still nothing.

I get the error

Cannot run program "C:\Windows\System32\cmd.exe /c C:\"Program Files"\Java\jdk1.6.0_23\bin\javac.exe": CreateProcess error=2, The system cannot find the file specified

but if i copy the command and run it from the command line it works fine.

I am aware of using the JavaCompiler class to compile my files but i would prefer to get this problem fixed first as i can't run any dos application or .bat file from Java. I can run GUI programs like notepad.exe fine though.

String[]  commands = new String[]{
             "C:\\Windows\\System32\\cmd.exe  /c C:\\\"Program Files\"\\Java\\jdk1.6.0_23\\bin\\javac.exe"
          };

  logger.log(Level.INFO, "About to run javac with the command below:");
  String commandToOutput = "";
  for (String command : commands) {
     commandToOutput += command + " ";
  }
  logger.log(Level.INFO, commandToOutput);



  ProcessBuilder processBuilder = new ProcessBuilder(commands);
  Process p = processBuilder.start();

Edit 2

String[] commands = new String[]{
         "C:\\\"Program Files\"\\Java\\jdk1.6.0_23\\bin\\javac.exe", "-d", "\"" + tempDir + "\"", "-classpath", classpath
      };

Edit 3

why is it that the second commands array works but the first does not below.

//this gives me CreateProcess error=5, Access is denied
      commands = new String[]{
                 "C:\\\"Program Files\"\\Java\\jdk1.6.0_23\\bin\\javac.exe"
              };

//this works
      commands = new String[]{
                 "C:\\Windows\\System32\\cmd.exe",
                 "/c",
                 "C:\\\"Program Files\"\\Java\\jdk1.6.0_23\\bin\\javac.exe",
              };

Answer 1

The string array that you pass to ProcessBuilder should contain one argument per array element, not everything in a single big string.

Try this:

String[] commands = new String[] 
{
  "C:\\Windows\\System32\\cmd.exe", 
  "/c", 
  "C:\\\"Program Files\"\\Java\\jdk1.6.0_23\\bin\\javac.exe"
};

Btw: there is no need to call cmd.exe, you can pass javac.exe directly to the ProcessBuilder

ProcessBuilder builder = new ProcessBuilder(
   "C:\\\"Program Files\"\\Java\\jdk1.6.0_23\\bin\\javac.exe", "\\Path\\To\\MyClass.java"
);

Answer 2

You have to read from process.getInputStream() yourself. As far as I know, processes' output doesn't automatically show on stdout.

Answer 3

You're using the wrong method of process builder. Use the single string version, i.e. don't pass a string array, just pass a string. The string array version is for when you've already already divided up the command into the program, its options, and its the arguments. As it stands now, its looking for a program executable file called C:\\Windows\\System32\\cmd.exe /c C:\\\"Program Files\"\\Java\\jdk1.6.0_23\\bin\\javac.exe.

Alternatively, split your command into the program and arguments in the string array and then you can use the String array version of process builder.

String[] = new String[] {
    "C:\\Windows\\System32\\cmd.exe",
    "/c",
    "C:\\\"Program Files\"\\Java\\jdk1.6.0_23\\bin\\javac.exe"
}

And