JOPT SIMPLE common problems and solutions (Common Privems and Solutions for Jopt Simple)
Jopt Simple is a Java library for processing and analyzing command line parameters.This article will introduce some common problems and solutions of JOPT SIMPLE, and provide the corresponding Java code examples.
Question 1: How to analyze and get command line parameters?
Solution: Use Jopt Simple's OptionParser class to parse the command line parameters, and then use the getOptionValue () method to obtain the value of the parameter.The following is an example code:
import joptsimple.OptionParser;
import joptsimple.OptionSet;
public class CommandLineParser {
public static void main(String[] args) {
OptionParser parser = new OptionParser();
parser.accepts("input").withRequiredArg();
parser.accepts("output").withRequiredArg();
OptionSet options = parser.parse(args);
String input = (String) options.valueOf("input");
String output = (String) options.valueOf("output");
System.out.println ("Input file:" + input);
System.out.println ("output file:" + output);
}
}
Question 2: How to define the options and descriptions of the command line parameters?
Solution: Use the accesss () method of the OptionParser class to define the options of the command line parameters, and use the Describedas () method to describe the option.The following is an example code:
import joptsimple.OptionParser;
import joptsimple.OptionSet;
import joptsimple.OptionSpec;
public class CommandLineParser {
public static void main(String[] args) {
OptionParser parser = new OptionParser();
OptionSpec<String> input = parser.accepts("input")
.withRequiredArg()
.descripedas ("Input file");
OptionSpec<String> output = parser.accepts("output")
.withRequiredArg()
.descripedas ("output file");
OptionSet options = parser.parse(args);
System.out.println ("Input file:" + Options.Valueof (input));
System.out.println ("Output file:" + Options.Valueof (output));
}
}
Question 3: How to deal with the Boolean type command line options?
Solution: Use the accesss () method of the OptionParser class to define the command line options of the Boolean type, and use the NoArgument () method to specify the option without parameters.The following is an example code:
import joptsimple.OptionParser;
import joptsimple.OptionSet;
import joptsimple.OptionSpec;
public class CommandLineParser {
public static void main(String[] args) {
OptionParser parser = new OptionParser();
OptionSpec<Void> verbose = parser.accepts("verbose")
.withOptionalArg()
.ofType(Void.class)
.descripedas ("Print Details");
OptionSet options = parser.parse(args);
if (options.has(verbose)) {
System.out.println ("Verbose mode has been enabled");
} else {
System.out.println ("Verbose mode is not enabled");
}
}
}
Question 4: How to deal with the default value of the parameter?
Solution: Use the defaultSto () method of OptionSpec to specify the default value of the command line option.The following is an example code:
import joptsimple.OptionParser;
import joptsimple.OptionSet;
import joptsimple.OptionSpec;
public class CommandLineParser {
public static void main(String[] args) {
OptionParser parser = new OptionParser();
OptionSpec<String> input = parser.accepts("input")
.withRequiredArg()
.defaultsTo("input.txt")
.descripedas ("Input file");
OptionSet options = parser.parse(args);
System.out.println ("Input file:" + Options.Valueof (input));
}
}
Through the above common problems and solutions, you can better understand and use the Jopt Simple library to process and analyze command line parameters.
