Google Options (Devtools) Java Library (GOOGLE Options (Devtools): A user guide in java class libraares)
Guide to use the usage guidelines in class libraries in class libraries of Google Options (Devtools)
preface:
Google Options is a powerful development tool that provides rich functions for Java developers.This article will introduce you to how to use Google Options (DevTools) Java library and provide some Java code examples to help you better understand and apply this tool.
1. Introduction to Google Options (DEVTools)
Google Options (DevTools) is a Java class library for processing and parsing the command line options.It can help developers handle the command line parameters more easily and provide some convenient functions, such as option verification, simplified option access, etc.
2. Install and import Google Options (DevTools)
To use Google Options (Devtools), you need to install it first and import it into your Java project.You can install and import through the following steps:
Step 1: Download the Google Options (DEVTools) library file.
Step 2: Add library files to the class path of your Java project.
3. The basic usage of Google Options (DevTools)
Here are some basic usage examples of how to use Google Options (Devtools):
Example 1: Create an Options object and add options
import com.google.devtools.common.options.OptionsParser;
import com.google.devtools.common.options.OptionsBase;
import com.google.devtools.common.options.Option;
import java.io.File;
public class MyOptions extends OptionsBase {
@Option(name = "input", abbrev = 'i', help = "Input file", category = "input")
public File inputFile;
@Option(name = "output", abbrev = 'o', help = "Output file", category = "output")
public File outputFile;
}
public class Main {
public static void main(String[] args) {
MyOptions options = new MyOptions();
OptionsParser parser = OptionsParser.newOptionsParser(MyOptions.class);
parser.parseAndExitUponError(args);
options = parser.getOptions(MyOptions.class);
// Access options
System.out.println ("Input file:" + Options.inputfile.getabsolutePath ());
System.out.println ("output file:" + options.outputfile.getabsolutepath ());
}
}
Example 2: Transfer options in the command line
java Main --input /path/to/input.txt --output /path/to/output.txt
4. Google Options (DEVTools) advanced usage
Google Options (Devtools) also provides some advanced features to meet more complicated scene needs.Here are some examples:
Example 3: Optional verification
You can use @Option for option verification to ensure that the options pass to meet specific requirements.For example, the following code fragment shows how to use option verification to require the suffix name of the input file and output file must be .txt.
import com.google.devtools.common.options.OptionsParser;
import com.google.devtools.common.options.OptionsBase;
import com.google.devtools.common.options.Option;
import java.io.File;
public class MyOptions extends OptionsBase {
@Option(name = "input", abbrev = 'i', help = "Input file", category = "input",
validator = com.google.devtools.common.options.FileValidator.class,
required = true, allowMultiple = false)
public File inputFile;
@Option(name = "output", abbrev = 'o', help = "Output file", category = "output",
validator = com.google.devtools.common.options.FileValidator.class,
required = true, allowMultiple = false)
public File outputFile;
}
public class Main {
public static void main(String[] args) {
MyOptions options = new MyOptions();
OptionsParser parser = OptionsParser.newOptionsParser(MyOptions.class);
parser.parseAndExitUponError(args);
options = parser.getOptions(MyOptions.class);
// Access options
System.out.println ("Input file:" + Options.inputfile.getabsolutePath ());
System.out.println ("output file:" + options.outputfile.getabsolutepath ());
}
}
Example 4: Use the default value
You can set the default value in the option definition and use the default value when the option is not specified.For example, the following code fragment shows how to use the default output file path when the output file is not specified.
import com.google.devtools.common.options.OptionsParser;
import com.google.devtools.common.options.OptionsBase;
import com.google.devtools.common.options.Option;
import java.io.File;
public class MyOptions extends OptionsBase {
@Option(name = "input", abbrev = 'i', help = "Input file", category = "input",
validator = com.google.devtools.common.options.FileValidator.class,
required = true, allowMultiple = false)
public File inputFile;
@Option(name = "output", abbrev = 'o', help = "Output file", category = "output",
defaultValue = "/path/to/default_output.txt",
validator = com.google.devtools.common.options.FileValidator.class,
required = true, allowMultiple = false)
public File outputFile;
}
public class Main {
public static void main(String[] args) {
MyOptions options = new MyOptions();
OptionsParser parser = OptionsParser.newOptionsParser(MyOptions.class);
parser.parseAndExitUponError(args);
options = parser.getOptions(MyOptions.class);
// Access options
System.out.println ("Input file:" + Options.inputfile.getabsolutePath ());
System.out.println ("output file:" + options.outputfile.getabsolutepath ());
}
}
in conclusion:
This article introduces how to use Google Options (DevTools) Java library and some Java code examples.By using Google Options, you can easily handle the command line options and improve development efficiency by verifying and default values.Hope this article will help you when you use Google Options (Devtools)!
