"intelligently" parsing user input arguments

Question

I have a program where commands are executed through Runtime.getRuntime().exec(cmdArray[]). The user can append additional switches to these commands by entering them in a textbox.

Example:

cmdArray[] = {"someprogram", "--something", "123"} //this is the initial command
//textbox is   -A "bla bla bla"   notice the quotes

//do something...

cmdArray[] = {"someprogram", "--something", "123", "-A", "bla bla bla"} //parsed array

Is there a java function that would allow me to do this? or do I have to write it myself (sounds tedious since I have to handle the single and double quotes, all the escaping etc...)?

Thanks

EDIT: Didn't want the extra dependency so I wrote a simple method, it doesn't cover everything but it does what I want

public String[] getCmdArray(String cmd) { // Parses a regular command line and returns it as a string array for use with Runtime.exec()
    ArrayList<String> cmdArray = new ArrayList<String>();
    StringBuffer argBuffer = new StringBuffer();
    char[] quotes = {'"', '\''};
    char currentChar = 0, protect = '\\', separate = ' ';
    int cursor = 0;
    cmd = cmd.trim();
    while(cursor < cmd.length()) {
        currentChar = cmd.charAt(cursor);

        // Handle protected characters
        if(currentChar == protect) {
            if(cursor + 1 < cmd.length()) {
                char protectedChar = cmd.charAt(cursor + 1);
                argBuffer.append(protectedChar);
                cursor += 2;
            }
            else
                return null; // Unprotected \ at end of cmd
        }

        // Handle quoted args
        else if(inArray(currentChar, quotes)) {
            int nextQuote = cmd.indexOf(currentChar, cursor + 1);
            if(nextQuote != -1) {
                cmdArray.add(cmd.substring(cursor + 1, nextQuote));
                cursor = nextQuote + 1;
            }
            else
                return null; // Unprotected, unclosed quote
        }

        // Handle separator
        else if(currentChar == separate) {
            if(argBuffer.length() != 0)
                cmdArray.add(argBuffer.toString());
            argBuffer.setLength(0);
            cursor++;
        }

        else {
            argBuffer.append(currentChar);
            cursor++;
        }
    }

    if(currentChar != 0) // Handle the last argument (doesn't have a space after it)
        cmdArray.add(argBuffer.toString());

    return cmdArray.toArray(new String[cmdArray.size()]);
}

public boolean inArray(char needle, char[] stack) {
    for(char c : stack)
        if(needle == c)
            return true;
    return false;
}

I'm pretty sure you have to handle this yourself. – Eric Stein Aug 23 '13 at 13:35 — Eric Stein, Aug 23 '13 at 13:35

score 0 · Answer 1 · answered Aug 23 '13 at 13:51

0

Use Apache Common CLI library. It can parse options and arguments very well. http://commons.apache.org/proper/commons-cli/

answered Aug 23 '13 at 13:51

KKKCoder

903
9
18

score 0 · Answer 2 · edited May 23 '17 at 12:28

There are numerous Java libraries "out there" that can help you with command line parsing; see How to parse command line arguments in Java? for examples.

However, parsing command arguments "intelligently" depends on where you are coming from:

If you want something that will parse command arguments according to a consistent syntax or meta-syntax, then some of those examples will surely do that.
If you want something that will magically understand what the user really means, then you are dreaming

"intelligently" parsing user input arguments

2 Answers2