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(JSAP.INTEGER_PARSER)
.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(JSAP.STRING_PARSER)
.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]$java com.martiansoftware.jsap.examples.Manual_HelloWorld_5 -n 2 -n 4Usage: java com.martiansoftware.jsap.examples.Manual_HelloWorld_5 -n <count> [-v|--verbose] name1 name2 ... nameN[mlamb@morbo]$java com.martiansoftware.jsap.examples.Manual_HelloWorld_5 --nosuchflagUsage: java com.martiansoftware.jsap.examples.Manual_HelloWorld_5 -n <count> [-v|--verbose] name1 name2 ... nameN
Note that the IDs of the "count" FlaggedOption
and the "name" UnflaggedOption were used
in the automatically-generated usage information. As of v1.4, this can
be overridden via setUsageName(
on any parameters. (Thanks to Andreas Hochsteger for the suggestion!)String)