argument-parser

Examples

Below given examples are for demonstrating how the argument-parser library can be used in various scenarios. Each of the examples will have these:

Usage expression
Data Class
Demo Driver program
Console output

Note: To run the demo driver program, dependency jars must be in the classpath. I used below command to include the jars in classpath:

bash$ export CLASSPATH=.:~/.m2/repository/org/slf4j/slf4j-api/1.7.25/slf4j-api-1.7.25.jar:~/.m2/repository/com/github/easy-develop/core-utils/1.0.0/core-utils-1.0.0.jar:~/.m2/repository/org/slf4j/slf4j-simple/1.7.25/slf4j-simple-1.7.25.jar
bash$

You can include the jars in whatever way suits you.

A simple case

The usage expression is: -m minute -s seconds

Data class is:

package com.easy.argparse.demo;

public class ArgumentData {
    private int minute;
    private int seconds;

    public int getMinute() {
        return minute;
    }

    public void setMinute(int minute) {
        this.minute = minute;
    }

    public int getSeconds() {
        return seconds;
    }

    public void setSeconds(int seconds) {
        this.seconds = seconds;
    }
}

The demo driver program is:

package com.easy.argparse.demo;

import com.easy.argparse.ArgumentParser;

public class ArgParserDemo {
    public static void main(String[] args) {
        String usageExpression = "-m minute -s seconds";
        ArgumentParser argParser = new ArgumentParser(usageExpression, ArgumentData.class);
        ArgumentData argData = (ArgumentData) argParser.parse(args);
        System.out.println("Minute: " + argData.getMinute() + ", Seconds: " + argData.getSeconds());
    }
}

And the console output is:

bash$ java com.easy.argparse.demo.ArgParserDemo -m 30 -s 45
Minute: 30, Seconds: 45

With optional arguments

The optional arguments can be specified within square brackets in the usage expression. Here is the usage expression: -m minute [ -s seconds ] The seconds is an optional argument in this usage expression

The data class is:

package com.easy.argparse.demo;

public class ArgumentData {
    private int minute;
    private int seconds;

    public int getMinute() {
        return minute;
    }

    public void setMinute(int minute) {
        this.minute = minute;
    }

    public int getSeconds() {
        return seconds;
    }

    public void setSeconds(int seconds) {
        this.seconds = seconds;
    }
}

The demo driver program is:

package com.easy.argparse.demo;

import com.easy.argparse.ArgumentParser;

public class ArgParserDemo {
    public static void main(String[] args) {
        String usageExpression = "-m minute -s seconds";
        ArgumentParser argParser = new ArgumentParser(usageExpression, ArgumentData.class);
        ArgumentData argData = (ArgumentData) argParser.parse(args);
        System.out.println("Minute: " + argData.getMinute() + ", Seconds: " + argData.getSeconds());
    }
}

And the console output is:

bash$ java com.easy.argparse.demo.ArgParserDemo -m 30
Minute: 30, Seconds: 0
bash$ java com.easy.argparse.demo.ArgParserDemo -m 30 -s 20
Minute: 30, Seconds: 20

Note: The value of seconds takes default value for int (i.e. 0) when not specified in command line arguments

Using alias for options

The options to be specified in command line arguments can have aliases defined through the usage expression. Here is the usage expression: -m|--min minute -s seconds This means that minute can be specified through option -m or --min

The data class is:

package com.easy.argparse.demo;

public class ArgumentData {
    private int minute;
    private int seconds;

    public int getMinute() {
        return minute;
    }

    public void setMinute(int minute) {
        this.minute = minute;
    }

    public int getSeconds() {
        return seconds;
    }

    public void setSeconds(int seconds) {
        this.seconds = seconds;
    }
}

The demo driver program is:

package com.easy.argparse.demo;

import com.easy.argparse.ArgumentParser;

public class ArgParserDemo {
    public static void main(String[] args) {
        String usageExpression = "-m minute [ -s seconds ]";
        ArgumentParser argParser = new ArgumentParser(usageExpression, ArgumentData.class);
        ArgumentData argData = (ArgumentData) argParser.parse(args);
        System.out.println("Minute: " + argData.getMinute() + ", Seconds: " + argData.getSeconds());
    }
}

And the console output is:

bash$ java com.easy.argparse.demo.ArgParserDemo -s 20 -m 45
Minute: 45, Seconds: 20
bash$ java com.easy.argparse.demo.ArgParserDemo --min 45 -s 20
Minute: 45, Seconds: 20

Note that output with -m is same as that with --min. It should also be noted that values in command line arguments need not be as per order given in usage expression

Array in command line argument

A value in the command line argument can be specified to be an array. Here is the usage expression: -u userIds

The data class is:

package com.easy.argparse.demo;

public class ArgumentData {
    private int[] userIds;

    public int[] getUserIds() {
        return userIds;
    }

    public void setUserIds(int[] userIds) {
        this.userIds = userIds;
    }
}

The demo driver program is:

package com.easy.argparse.demo;

import com.easy.argparse.ArgumentParser;

public class ArgParserDemo {
    public static void main(String[] args) {
        String usageExpression = "-u userIds";
        ArgumentParser argParser = new ArgumentParser(usageExpression, ArgumentData.class);
        ArgumentData argData = (ArgumentData) argParser.parse(args);
        System.out.println("Specified users are given below:");
        for(int id : argData.getUserIds()){
            System.out.println("User ID = [" + id + "]");
        }
    }
}

And the console output is:

bash$ java com.easy.argparse.demo.ArgParserDemo -u "1818, 9856, 7812"
Specified users are given below:
User ID = [1818]
User ID = [9856]
User ID = [7812]

It is to note that if not specified otherwise, elements of the array are supposed to be separated by , and whitespace around the array elements are automatically removed

Array with user defined delimiter

We can specify the array elements to be separated by some delimiter other than ,. Here is the usage expression: -u userIds

The data class is:

package com.easy.argparse.demo;

public class ArgumentData {
    private int[] userIds;

    public int[] getUserIds() {
        return userIds;
    }

    public void setUserIds(int[] userIds) {
        this.userIds = userIds;
    }
}

The demo driver program is:

package com.easy.argparse.demo;

import com.easy.argparse.ArgumentParser;

public class ArgParserDemo {
    public static void main(String[] args) {
        String usageExpression = "-u userIds";
        ArgumentParser argParser = new ArgumentParser(usageExpression, ArgumentData.class, "|");
        ArgumentData argData = (ArgumentData) argParser.parse(args);
        System.out.println("Specified users are given below:");
        for(int id : argData.getUserIds()){
            System.out.println("User ID = [" + id + "]");
        }
    }
}

And the console output is:

bash$ java com.easy.argparse.demo.ArgParserDemo -u "1818 | 9856 | 7812"
Specified users are given below:
User ID = [1818]
User ID = [9856]
User ID = [7812]

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