Java Serialized HashMap<String, String | Boolean> --> JSON

parser.kt

// $ kotlinc-jvm -include-runtime -d parser.jar parser.kt
// $ java -jar parser.jar

import java.io.Serializable
import java.io.ObjectInputStream
import java.io.FileInputStream
import java.util.HashMap

// simple, and wrong escaping for JSON
fun escapeStr(s: String): String =
	'"' +
	s.replace("\\", "\\\\").replace("\"", "\\\"").replace("\n", "\\n") +
	'"'


fun main() {
	FileInputStream("./input-file").use { fis ->
		ObjectInputStream(fis).use { ois ->
			val map = ois.readObject()
			if (map !is HashMap<*, *>) return

			var first = true

			for ((key, value) in map) {
				if (key !is String) return
				val escapedKey = escapeStr(key)
				val prefix = if (first) { '{' } else { ',' }

				when (value) {
					is String -> {
						println("${prefix} $escapedKey: ${escapeStr(value)}")
					}
					is Boolean -> {
						println("${prefix} $escapedKey: $value")
					}
				}

				first = false
			}

			println('}')
		}
	}
}