1. There are two types of lines: natural line and logical line.
2. Natural lines are separated by \ n, \ r, \ r \ n or at the end of the stream.
3. A logical line may span multiple adjacent natural lines by escaping the line terminator sequence with a backslash.
4. The whitespace character group at the beginning of the second and subsequent natural lines in the logical line is discarded.
5. Whitespace characters are spaces (``, \ u0020), tabs (\ t, \ u0009), and line feeds (\ f, \ u000C).
6. As explicitly stated in the specification, _ "When determining if a line terminator is escaped, it is not enough to look at the character before the line terminator sequence, because the line terminator is escaped. Must have a series of odd backslashes. The input is processed from left to right, so there are 2n (non-zero even) backslashes before (or elsewhere) the line terminator. If present, n backslashes are encoded after escaping. "_
7. = is used as the key / value delimiter.
8. : Is also used as a key / value delimiter.
9. The delimiter between the key and the value is optional.
10. Comment lines have # or ! as the first non-whitespace character. That is, whitespace characters before # and ! are allowed.
11. Escaping line terminators with a backslash does not allow comment lines to span multiple lines.
12. As explicitly stated in the specification, =, : and whitespace characters can also be embedded in the key by escaping them with a backslash.
13. Even line terminators can be included by using the \ r and \ n escase sequences.
14. If the value is omitted, it is treated as an empty string.
15. \ uxxxx stands for Unicode character.
16. Backslashes placed before characters that do not make up a valid escape character are not treated as an error and are simply dropped.

** Examples of Properties file **

That's why, for example, if test.properties has the following content:

# A comment line that starts with '#'.
   # This is a comment line having leading white spaces.
! A comment line that starts with '!'.

key1=value1
  key2 : value2
    key3 value3
key\
  4=value\
    4
\u006B\u0065\u00795=\u0076\u0061\u006c\u0075\u00655
\k\e\y\6=\v\a\lu\e\6

\:\ \= = \\colon\\space\\equal

It should be interpreted as the following key-value pair group.

** Code example **

NuGet The PropertiesLoader class contained in the package" Authlete.Authlete "is the Properties file. Can interpret the specifications of. The following code example

using System;
using System.IO;
using System.Collections.Generic;
using Authlete.Util;

namespace MyApp
{
    class Program
    {
        public static void Main(string[] args)
        {
            string file = "test.properties";
            IDictionary<string, string> properties;

            using (TextReader reader = new StreamReader(file))
            {
                properties = PropertiesLoader.Load(reader);
            }
        
            foreach (var entry in properties)
            {
                Console.WriteLine($"{entry.Key} = {entry.Value}");
            }
        }
    }
}

Produces the following output.

key1 = value1
key2 = value2
key3 = value3
key4 = value4
key5 = value5
key6 = value6
: = = \colon\space\equal

Here's a similar code in Java:

import java.util.*;
import java.io.*;

public class Program
{
    public static void main(String[] args) throws IOException
    {
        String file = "test.properties";
        Properties properties = new Properties();

        try (Reader reader = new FileReader(file))
        {
             properties.load(reader);
        }

        for (Map.Entry<Object, Object> entry : properties.entrySet())
        {
            System.out.format("%s = %s\n", entry.getKey(), entry.getValue());
        }    
    }
}

Source code

The source code for PropertiesLoader.cs </ code> is authlete-csharp It exists in (: //github.com/authlete/authlete-csharp). Also, the xUnit test group for PropertiesLoader is [PropertiesLoaderTest.cs](https://github.com/authlete/authlete-csharp/blob/ It is described in master / Authlete.Tests / Util / PropertiesLoaderTest.cs) </ code>.