Interacting with the Environment - Java - page 73

For backward compatibility with people who learned to use the Unix version in C, the get-
opt() method can be used normally in a while loop. It returns once for each valid option
found, returning the value of the character that was found or the constant DONE when all op-
tions (if any) have been processed.

Here is a complete program that uses my GetOpt class just to see if there is a -h (for help)
argument on the command line:

public public class class GetOptSimple GetOptSimple {

public public static void main ( String [] args ) {

GetOpt go = new

static void

new GetOpt ( "h" );

char char c ;

while while (( c = go . getopt ( args )) != 0 ) {

switch

switch ( c ) {
case case 'h' :

helpAndExit ( 0 );
break

break ;
default

default :
System . err . println ( "Unknown option in " +
args [ go . getOptInd ()- 1 ]);
helpAndExit ( 1 );

}

}
System . out . println ();

}

/** Stub for providing help on usage
* You can write a longer help than this, certainly.
*/
static static void int returnValue ) {

System . err . println ( "This would tell you how to use this program" );
System . exit ( returnValue );

void helpAndExit ( int

}

}

This longer demo program has several options:

public public class class GetOptDemoNew GetOptDemoNew {

public public static static void void main ( String [] argv ) {

boolean boolean numeric_option = false false ;

boolean boolean errs = false false ;

String outputFileName = null null ;