Java Runtime Execute different inside program than in command line?

Question

Im trying to compile some java files using the Runtime.getRuntime.exec(command) and im generating the command. The code below shows what i am doing:

String command = "javac ";
    for(String s: this.getPackages())
    {
        command = command + "/home/benuni/CompileFiles/" + project + "/" + s + "/*.java ";
    }

    try {
        System.out.println("command: '"+ command +"'");
        Process pro = Runtime.getRuntime().exec(command);
         printLines(" stderr:", pro.getErrorStream());

        pro.waitFor();

This is giving the following output:

command: 'javac /home/benuni/CompileFiles/HelloWorldProject/HelloWorldPackage/*.java '
stderr: javac: file not found:     /home/benuni/CompileFiles/HelloWorldProject/HelloWorldPackage/*.java
 stderr: Usage: javac <options> <source files>
 stderr: use -help for a list of possible options

and its not working.. but if i copy the command into my shell, it works no problem... any ideas?

Try replacing *.java with any one file that is in /home/benuni/CompileFiles/HelloWorldProject/HelloWorldPackage/ — Miserable Variable
– Miserable Variable, Commented Aug 23, 2012 at 21:51

stevevls · Accepted Answer · 2012-08-23 21:58:47Z

4

Java doesn't expand the * wildcard for you. That's a facility of the shell. Instead, you'll need to list the directory to get all of the contained files.

Something like this would do the trick to build up your command:

    File[] files = new File("/home/benuni/CompileFiles/" + project + "/" + s).listFiles(new FilenameFilter() {
        @Override
        public boolean accept(File dir, String name) {
            return name.endsWith(".java");
        }
    });

    StringBuilder command = new StringBuilder("javac");
    for(File file : files) {
        command.append(" ").append(file.getAbsolutePath());
    }

edited Aug 23, 2012 at 21:58

answered Aug 23, 2012 at 21:51

stevevls

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Hot Licks · Accepted Answer · 2012-08-23 21:51:37Z

2

When you enter from the command line, the command analyzer expands * into a list of files. When you use Runtime.exec that expansion does not occur, and you must explicitly specify the entire list.

answered Aug 23, 2012 at 21:51

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Miserable Variable · Accepted Answer · 2012-08-23 21:55:23Z

1

One option is to provide the actual list of file names to javac. Another is to let shell do it, using the command

/bin/sh -c javac /home/benuni/CompileFiles/HelloWorldProject/HelloWorldPackage/*.java

answered Aug 23, 2012 at 21:55

Miserable Variable

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