JarCastingsimple-argparse4j
Very simple argument parser, inspired by argparse4j (https://argparse4j.github.io/).
Normally, I use argparse4j for all my little command-line based tools. But for one project, I needed to be able to have unparsed options that resemble options, as I needed to pass on these options to processes that get launched. I didn't find a solution to get argparse4j to be more lenient, hence I implemented a very simple version of a command-line option parser inspired by argparse4j.
Supported data types
The parser supports the following data types:
- string
- boolean
- byte
- short
- int
- long
- float
- double
- file (any file/dir, existing file/dir, non-existing file/dir)
Apart from boolean all data types require an argument.
Defining options
Here is an example for defining an option:
import com.github.fracpete.simpleargparse4j.ArgumentParser;
...
ArgumentParser parser = new ArgumentParser(getName());
parser.addOption("--name")
.dest("name")
.help("the name of the environment")
.required(true);
The parser will look for an option that starts with a flag of --name and stores the associated argument that it will find (using the key specified with dest(...)). help(...) specifies the help string. required(true) specifies that the user has to supply the argument (by default, options are optional).
It is also possible to supply two flags, e.g., a short form and a long version:
import com.github.fracpete.simpleargparse4j.ArgumentParser;
...
ArgumentParser parser = new ArgumentParser(getName());
parser.addOption("-n", "--name")
.dest("name")
.help("the name of the environment")
.required(true);
Other settings for ArgumentParser:
screenWidth(int)-- the width of the screen, which gets used when printing the help screen.breakChars(char[])-- the characters that are used to break long help lines into smaller ones to fit within the defined screen width.
Other settings for Option:
argument(boolean)-- specifies whether the option is a flag (false) or requires an argument (true). By setting thetypeof an option toboolean, this gets automatically set tofalse.multiple(boolean)-- specifies whether the option can occur multiple timessetDefault(...)-- sets the default value (if not a required option); in conjunction withmultiple(true), you have to set ajava.util.Listobjecttype(Type)-- sets the type to enforce when parsing the options rather than when retrieving them from theNamespaceobject, e.g.,doubleorboolean.metaVar(String)-- for setting the display string for the argument of an option (uses upper case). By default, thedestinationstring is used.
Parsing options
The following snippet parses the options (args) and returns them as Namespace object (parseArgs(String[]) method). In case of invalid options, missing required options or help being request, an ArgumentParserException is thrown. Using the parser's handleError(ArgumentParserException) you can output a help screen generated from the defined options.
import com.github.fracpete.simpleargparse4j.ArgumentParserException;
import com.github.fracpete.simpleargparse4j.Namespace;
...
Namespace ns;
try {
ns = parser.parseArgs(args);
}
catch (ArgumentParserException e) {
parser.handleError(e);
return !parser.getHelpRequested(); // help request is valid operation
}
Using parseArgs(String[],true) you can remove the all the parsed options from the provided string array. parseArgs(String[]) does not remove them by default.
Retrieving parsed values
Once the options have been parsed, you can retrieve (typed) from the Namespace object:
getString(String)-- returns the string associated with the provided keygetBoolean(String)-- returns the boolean associated with the provided key; whether atrueorfalsegets returned is determine by the default value. Without specifying an explicit default value,falsegets returned if the flag is present, otherwisetrue. You can invert this by simply usingsetDefault(true)when defining the option.getByte(String)-- returns the byte associated with the provided keygetShort(String)-- returns the short associated with the provided keygetInt(String)-- returns the integer associated with the provided keygetLong(String)-- returns the long associated with the provided keygetFloat(String)-- returns the float associated with the provided keygetDouble(String)-- returns the double associated with the provided keygetFile(String)-- returns the double associated with the provided keygetList(String)-- returns the list associated with the provided key
Example
The following example configures several parameters, not all of them required. It then parses the arguments provided to the application and outputs the parsed values.
import com.github.fracpete.simpleargparse4j.ArgumentParser;
import com.github.fracpete.simpleargparse4j.ArgumentParserException;
import com.github.fracpete.simpleargparse4j.Namespace;
public static void main(String[] args) {
// define the options
ArgumentParser parser = new ArgumentParser("create");
parser.addOption("--name")
.dest("name")
.help("the name of the environment")
.required(true);
parser.addOption("--java")
.dest("java")
.help("the full path of the java binary to use for launching Weka")
.setDefault("");
parser.addOption("--memory")
.dest("memory")
.help("the heap size to use for launching Weka (eg '1024m' or '2g')")
.setDefault("");
parser.addOption("--weka")
.dest("weka")
.help("the full path to the weka.jar to use")
.required(true);
parser.addOption("--wekafiles")
.dest("wekafiles")
.help("the full path to the 'wekafiles' directory to initialize the environment with")
.setDefault("");
parser.addOption("--envvar")
.dest("envvar")
.help("optional environment variables to set (key=value)")
.multiple(true);
// parse the options
Namespace ns;
try {
ns = parser.parseArgs(args, true);
}
catch (ArgumentParserException e) {
parser.handleError(e);
return false;
}
// output the parsed values
System.out.println("Name: " + ns.getString("name"));
System.out.println("Jav: " + ns.getString("java"));
System.out.println("Memory: " + ns.getString("memory"));
System.out.println("Weka jar: " + ns.getString("weka"));
System.out.println("Env. vars: " + ns.getList("envvar"));
}
Maven
Add the following dependency to your pom.xml:
<dependency>
<groupId>com.github.fracpete</groupId>
<artifactId>simple-argparse4j</artifactId>
<version>0.0.13</version>
</dependency>