All or the previous examples showed command lines flawlessly typed by the user. This, of course, never happens. One way to handle this is to print usage information:
public static void main(String[] args) throws Exception { JSAP jsap = new JSAP(); FlaggedOption opt1 = new FlaggedOption("count") .setStringParser(new IntegerStringParser()) .setDefault("1") .setRequired(true) .setShortFlag('n') .setLongFlag(JSAP.NO_LONGFLAG); jsap.registerParameter(opt1); Switch sw1 = new Switch("verbose") .setShortFlag('v') .setLongFlag("verbose"); jsap.registerParameter(sw1); UnflaggedOption opt2 = new UnflaggedOption("name") .setStringParser(new StringStringParser()) .setDefault("World") .setRequired(true) .setGreedy(true); jsap.registerParameter(opt2); JSAPResult config = jsap.parse(args); // check whether the command line was valid, and if it wasn't, // display usage information and exit. if (!config.success()) { System.err.println(); System.err.println("Usage: java " + Manual_HelloWorld_5.class.getName()); System.err.println(" " + jsap.getUsage()); System.err.println(); System.exit(1); } String[] names = config.getStringArray("name"); for (int i = 0; i < config.getInt("count"); ++i) { for (int j = 0; j < names.length; ++j) { System.out.println((config.getBoolean("verbose") ? "Hello" : "Hi") + ", " + names[j] + "!"); } } }
[mlamb@morbo]$ java com.martiansoftware.jsap.examples.Manual_HelloWorld_5 -n 2 -n 4 Usage: java com.martiansoftware.jsap.examples.Manual_HelloWorld_5 -n <count> [-v|--verbose] name1 name2 ... nameN [mlamb@morbo]$ java com.martiansoftware.jsap.examples.Manual_HelloWorld_5 --nosuchflag Usage: java com.martiansoftware.jsap.examples.Manual_HelloWorld_5 -n <count> [-v|--verbose] name1 name2 ... nameN