How to resolve the algorithm Read a configuration file step by step in the Kotlin programming language

Published on 22 June 2024 08:30 PM

How to resolve the algorithm Read a configuration file step by step in the Kotlin programming language

Table of Contents

Problem Statement

The task is to read a configuration file in standard configuration file format, and set variables accordingly. For this task, we have a configuration file as follows:

For the task we need to set four variables according to the configuration entries as follows:

We also have an option that contains multiple parameters. These may be stored in an array.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Read a configuration file step by step in the Kotlin programming language

Explanation:

  1. Data Class Configuration:

    • Models a user configuration with various properties, such as fullName, favoriteFruit, needsPeeling, and otherFamily.
    • These properties are accessed using Kotlin's delegated property feature (val fullName: String by map).
  2. Main Function:

    • Input Reading: Reads lines from a text file src/configuration.txt that contains key-value pairs in a simple format.
  3. Preprocessing of Key-Value Pairs:

    • Removes empty lines, commented lines, and splits the remaining lines into key-value pairs.
  4. Configuration Map Initialization:

    • Initializes a mutable map with a default value for needsPeeling as false.
  5. Key-Value Processing Loop:

    • Iterates over the preprocessed key-value pairs.
    • For each pair, based on the key, it updates the configuration map with the appropriate value.
    • Any unexpected keys are logged.
  6. Creating the Configuration Object:

    • Creates an instance of the Configuration data class using the populated configuration map.
  7. Helper Functions:

    • commentedOut: Checks if a line is commented out (starting with "#" or ";").
    • toKeyValuePair: Splits a line into a Pair of key and value, handling empty values.

Overall: This Kotlin program reads a simple configuration file and parses it into a type-safe Configuration data class. It demonstrates basic data processing and delegated properties in Kotlin.

Source code in the kotlin programming language

import java.nio.charset.StandardCharsets
import java.nio.file.Files
import java.nio.file.Paths

data class Configuration(val map: Map<String, Any?>) {
    val fullName: String by map
    val favoriteFruit: String by map
    val needsPeeling: Boolean by map
    val otherFamily: List<String> by map
}

fun main(args: Array<String>) {
    val lines = Files.readAllLines(Paths.get("src/configuration.txt"), StandardCharsets.UTF_8)
    val keyValuePairs = lines.map{ it.trim() }
            .filterNot { it.isEmpty() }
            .filterNot(::commentedOut)
            .map(::toKeyValuePair)

    val configurationMap = hashMapOf<String, Any>("needsPeeling" to false)
    for (pair in keyValuePairs) {
        val (key, value) = pair
        when (key) {
            "FULLNAME"       -> configurationMap.put("fullName", value)
            "FAVOURITEFRUIT" -> configurationMap.put("favoriteFruit", value)
            "NEEDSPEELING"   -> configurationMap.put("needsPeeling", true)
            "OTHERFAMILY"    -> configurationMap.put("otherFamily", value.split(" , ").map { it.trim() })
            else             -> println("Encountered unexpected key $key=$value")
        }
    }
    println(Configuration(configurationMap))
}

private fun commentedOut(line: String) = line.startsWith("#") || line.startsWith(";")

private fun toKeyValuePair(line: String) = line.split(Regex(" "), 2).let {
    Pair(it[0], if (it.size == 1) "" else it[1])
}


  

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