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[BAEL-19882] - Move articles out of core-kotlin part1

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This commit is contained in:
catalin-burcea
2019-12-10 14:57:11 +02:00
parent 3517462948
commit a141ac01fd
42 changed files with 210 additions and 124 deletions
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6
core-kotlin/README.md
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@@ -24,12 +24,8 @@ This module contains articles about core Kotlin.
- [Try-with-resources in Kotlin](https://www.baeldung.com/kotlin-try-with-resources)
- [Regular Expressions in Kotlin](https://www.baeldung.com/kotlin-regular-expressions)
- [Objects in Kotlin](https://www.baeldung.com/kotlin-objects)
- [Reading from a File in Kotlin](https://www.baeldung.com/kotlin-read-file)
- [Guide to Kotlin @JvmField](https://www.baeldung.com/kotlin-jvm-field-annotation)
- [Filtering Kotlin Collections](https://www.baeldung.com/kotlin-filter-collection)
- [Writing to a File in Kotlin](https://www.baeldung.com/kotlin-write-file)
- [Lambda Expressions in Kotlin](https://www.baeldung.com/kotlin-lambda-expressions)
- [Kotlin String Templates](https://www.baeldung.com/kotlin-string-template)
- [Working with Enums in Kotlin](https://www.baeldung.com/kotlin-enum)
- [Create a Java and Kotlin Project with Maven](https://www.baeldung.com/kotlin-maven-java-project)
- [Reflection with Kotlin](https://www.baeldung.com/kotlin-reflection)
@@ -41,7 +37,6 @@ This module contains articles about core Kotlin.
- [Fuel HTTP Library with Kotlin](https://www.baeldung.com/kotlin-fuel)
- [Introduction to Kovenant Library for Kotlin](https://www.baeldung.com/kotlin-kovenant)
- [Converting Kotlin Data Class from JSON using GSON](https://www.baeldung.com/kotlin-json-convert-data-class)
- [Concatenate Strings in Kotlin](https://www.baeldung.com/kotlin-concatenate-strings)
- [Kotlin return, break, continue Keywords](https://www.baeldung.com/kotlin-return-break-continue)
- [Mapping of Data Objects in Kotlin](https://www.baeldung.com/kotlin-data-objects)
- [Initializing Arrays in Kotlin](https://www.baeldung.com/kotlin-initialize-array)
@@ -50,7 +45,6 @@ This module contains articles about core Kotlin.
- [Guide to Sorting in Kotlin](https://www.baeldung.com/kotlin-sort)
- [Dependency Injection for Kotlin with Injekt](https://www.baeldung.com/kotlin-dependency-injection-with-injekt)
- [Implementing a Binary Tree in Kotlin](https://www.baeldung.com/kotlin-binary-tree)
- [Generate a Random Alphanumeric String in Kotlin](https://www.baeldung.com/kotlin-random-alphanumeric-string)
- [Kotlin Contracts](https://www.baeldung.com/kotlin-contracts)
- [Operator Overloading in Kotlin](https://www.baeldung.com/kotlin-operator-overloading)
- [Inline Classes in Kotlin](https://www.baeldung.com/kotlin-inline-classes)

24
core-kotlin/src/main/kotlin/com/baeldung/filesystem/FileReader.kt
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@@ -1,24 +0,0 @@
package com.baeldung.filesystem
import java.io.File
class FileReader {
fun readFileLineByLineUsingForEachLine(fileName: String) = File(fileName).forEachLine { println(it) }
fun readFileAsLinesUsingUseLines(fileName: String): List<String> = File(fileName)
.useLines { it.toList() }
fun readFileAsLinesUsingBufferedReader(fileName: String): List<String> = File(fileName).bufferedReader().readLines()
fun readFileAsLinesUsingReadLines(fileName: String): List<String> = File(fileName).readLines()
fun readFileAsTextUsingInputStream(fileName: String) =
File(fileName).inputStream().readBytes().toString(Charsets.UTF_8)
fun readFileDirectlyAsText(fileName: String): String = File(fileName).readText(Charsets.UTF_8)
fun readFileUsingGetResource(fileName: String) = this::class.java.getResource(fileName).readText(Charsets.UTF_8)
fun readFileAsLinesUsingGetResourceAsStream(fileName: String) = this::class.java.getResourceAsStream(fileName).bufferedReader().readLines()
}

19
core-kotlin/src/main/kotlin/com/baeldung/filesystem/FileWriter.kt
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@@ -1,19 +0,0 @@
package com.baeldung.filesystem
import java.io.File
class FileWriter {
fun writeFileUsingPrintWriter(fileName: String, fileContent: String) =
File(fileName).printWriter().use { out -> out.print(fileContent) }
fun writeFileUsingBufferedWriter(fileName: String, fileContent: String) =
File(fileName).bufferedWriter().use { out -> out.write(fileContent) }
fun writeFileDirectly(fileName: String, fileContent: String) =
File(fileName).writeText(fileContent)
fun writeFileDirectlyAsBytes(fileName: String, fileContent: String) =
File(fileName).writeBytes(fileContent.toByteArray())
}

12
core-kotlin/src/main/kotlin/com/baeldung/kotlin/JvmSample.kt
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@@ -1,12 +0,0 @@
package com.baeldung.kotlin
class JvmSample(text:String) {
@JvmField
val sampleText:String = text
}
class CompanionSample {
companion object {
@JvmField val MAX_LIMIT = 20
}
}

115
core-kotlin/src/main/kotlin/com/baeldung/stringtemplates/Templates.kt
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@@ -1,115 +0,0 @@
package com.baeldung.stringtemplates
/**
* Example of a useful function defined in Kotlin String class
*/
fun padExample(): String {
return "Hello".padEnd(10, '!')
}
/**
* Example of a simple string template usage
*/
fun simpleTemplate(n: Int): String {
val message = "n = $n"
return message
}
/**
* Example of a string template with a simple expression
*/
fun templateWithExpression(n: Int): String {
val message = "n + 1 = ${n + 1}"
return message
}
/**
* Example of a string template with expression containing some logic
*/
fun templateWithLogic(n: Int): String {
val message = "$n is ${if (n > 0) "positive" else "not positive"}"
return message
}
/**
* Example of nested string templates
*/
fun nestedTemplates(n: Int): String {
val message = "$n is ${if (n > 0) "positive" else if (n < 0) "negative and ${if (n % 2 == 0) "even" else "odd"}" else "zero"}"
return message
}
/**
* Example of joining array's element into a string with a default separator
*/
fun templateJoinArray(): String {
val numbers = listOf(1, 1, 2, 3, 5, 8)
val message = "first Fibonacci numbers: ${numbers.joinToString()}"
return message
}
/**
* Example of escaping the dollar sign
*/
fun notAStringTemplate(): String {
val message = "n = \$n"
return message
}
/**
* Example of a simple triple quoted string
*/
fun showFilePath(): String {
val path = """C:\Repository\read.me"""
return path
}
/**
* Example of a multiline string
*/
fun showMultiline(): String {
val receipt = """Item 1: $1.00
Item 2: $0.50"""
return receipt
}
/**
* Example of a multiline string with indentation
*/
fun showMultilineIndent(): String {
val receipt = """Item 1: $1.00
>Item 2: $0.50""".trimMargin(">")
return receipt
}
/**
* Example of a triple quoted string with a not-working escape sequence
*/
fun showTripleQuotedWrongEscape(): String {
val receipt = """Item 1: $1.00\nItem 2: $0.50"""
return receipt
}
/**
* Example of a triple quoted string with a correctly working escape sequence
*/
fun showTripleQuotedCorrectEscape(): String {
val receipt = """Item 1: $1.00${"\n"}Item 2: $0.50"""
return receipt
}
fun main(args: Array<String>) {
println(padExample())
println(simpleTemplate(10))
println(templateWithExpression(5))
println(templateWithLogic(7))
println(nestedTemplates(-5))
println(templateJoinArray())
println(notAStringTemplate())
println(showFilePath())
println(showMultiline())
println(showMultilineIndent())
println(showTripleQuotedWrongEscape())
println(showTripleQuotedCorrectEscape())
}

67
core-kotlin/src/test/kotlin/com/baeldung/filesystem/FileReaderTest.kt
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@@ -1,67 +0,0 @@
package com.baeldung.filesystem
import org.junit.jupiter.api.Test
import kotlin.test.assertTrue
internal class FileReaderTest {
private val fileName = "src/test/resources/Kotlin.in"
private val fileReader = FileReader()
@Test
fun whenReadFileLineByLineUsingForEachLine_thenCorrect() {
fileReader.readFileLineByLineUsingForEachLine(fileName)
}
@Test
fun whenReadFileAsLinesUsingUseLines_thenCorrect() {
val lines = fileReader.readFileAsLinesUsingUseLines(fileName)
assertTrue { lines.contains("1. Concise") }
}
@Test
fun whenReadFileAsLinesUsingBufferedReader_thenCorrect() {
val lines = fileReader.readFileAsLinesUsingBufferedReader(fileName)
assertTrue { lines.contains("2. Safe") }
}
@Test
fun whenReadFileAsLinesUsingReadLines_thenCorrect() {
val lines = fileReader.readFileAsLinesUsingReadLines(fileName)
assertTrue { lines.contains("3. Interoperable") }
}
@Test
fun whenReadFileAsTextUsingInputStream_thenCorrect() {
val text = fileReader.readFileAsTextUsingInputStream(fileName)
assertTrue { text.contains("4. Tool-friendly") }
}
@Test
fun whenReadDirectlyAsText_thenCorrect() {
val text = fileReader.readFileDirectlyAsText(fileName)
assertTrue { text.contains("Hello to Kotlin") }
}
@Test
fun whenReadFileAsTextUsingGetResource_thenCorrect() {
val text = fileReader.readFileUsingGetResource("/Kotlin.in")
assertTrue { text.contains("1. Concise") }
}
@Test
fun whenReadFileUsingGetResourceAsStream_thenCorrect() {
val lines = fileReader.readFileAsLinesUsingGetResourceAsStream("/Kotlin.in")
assertTrue { lines.contains("3. Interoperable") }
}
}

43
core-kotlin/src/test/kotlin/com/baeldung/filesystem/FileWriterTest.kt
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@@ -1,43 +0,0 @@
package com.baeldung.filesystem
import org.junit.jupiter.api.Test
import java.io.File
import kotlin.test.assertEquals
internal class FileWriterTest {
private val fileName = "src/test/resources/Kotlin.out"
private val fileContent = "Kotlin\nConcise, Safe, Interoperable, Tool-friendly"
private val fileWriter = FileWriter()
@Test
fun whenWrittenWithPrintWriter_thenCorrect() {
fileWriter.writeFileUsingPrintWriter(fileName, fileContent)
assertEquals(fileContent, File(fileName).readText())
}
@Test
fun whenWrittenWithBufferedWriter_thenCorrect() {
fileWriter.writeFileUsingBufferedWriter(fileName, fileContent)
assertEquals(fileContent, File(fileName).readText())
}
@Test
fun whenWrittenDirectly_thenCorrect() {
fileWriter.writeFileDirectly(fileName, fileContent)
assertEquals(fileContent, File(fileName).readText())
}
@Test
fun whenWrittenDirectlyAsBytes_thenCorrect() {
fileWriter.writeFileDirectlyAsBytes(fileName, fileContent)
assertEquals(fileContent, File(fileName).readText())
}
}

26
core-kotlin/src/test/kotlin/com/baeldung/kotlin/JvmSampleTest.kt
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@@ -1,26 +0,0 @@
package com.baeldung.kotlin
import org.junit.Before
import org.junit.Test
import kotlin.test.assertTrue
class JvmSampleTest {
var sample = ""
@Before
fun setUp() {
sample = JvmSample("Hello!").sampleText
}
@Test
fun givenField_whenCheckValue_thenMatchesValue() {
assertTrue(sample == "Hello!")
}
@Test
fun givenStaticVariable_whenCheckValue_thenMatchesValue() {
// Sample when is treated as a static variable
assertTrue(CompanionSample.MAX_LIMIT == 20)
}
}

48
core-kotlin/src/test/kotlin/com/baeldung/kotlin/StringConcatenationTest.kt
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@@ -1,48 +0,0 @@
package com.baeldung.kotlin
import org.junit.Test
import kotlin.test.assertEquals
class StringConcatenationTest {
@Test
fun givenTwoStrings_concatenateWithTemplates_thenEquals() {
val a = "Hello"
val b = "Baeldung"
val c = "$a $b"
assertEquals("Hello Baeldung", c)
}
@Test
fun givenTwoStrings_concatenateWithPlusOperator_thenEquals() {
val a = "Hello"
val b = "Baeldung"
val c = a + " " + b
assertEquals("Hello Baeldung", c)
}
@Test
fun givenTwoStrings_concatenateWithStringBuilder_thenEquals() {
val a = "Hello"
val b = "Baeldung"
val builder = StringBuilder()
builder.append(a).append(" ").append(b)
val c = builder.toString()
assertEquals("Hello Baeldung", c)
}
@Test
fun givenTwoStrings_concatenateWithPlusMethod_thenEquals() {
val a = "Hello"
val b = "Baeldung"
val c = a.plus(" ").plus(b)
assertEquals("Hello Baeldung", c)
}
}

62
core-kotlin/src/test/kotlin/com/baeldung/random/RandomStringUnitTest.kt
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@@ -1,62 +0,0 @@
import org.apache.commons.lang3.RandomStringUtils
import org.junit.Before
import org.junit.jupiter.api.BeforeAll
import org.junit.jupiter.api.BeforeEach
import org.junit.jupiter.api.Test
import java.security.SecureRandom
import java.util.concurrent.ThreadLocalRandom
import kotlin.experimental.and
import kotlin.streams.asSequence
import kotlin.test.assertEquals
const val STRING_LENGTH = 10
const val ALPHANUMERIC_REGEX = "[a-zA-Z0-9]+"
class RandomStringUnitTest {
private val charPool : List<Char> = ('a'..'z') + ('A'..'Z') + ('0'..'9')
@Test
fun givenAStringLength_whenUsingJava_thenReturnAlphanumericString() {
var randomString = ThreadLocalRandom.current()
.ints(STRING_LENGTH.toLong(), 0, charPool.size)
.asSequence()
.map(charPool::get)
.joinToString("")
assert(randomString.matches(Regex(ALPHANUMERIC_REGEX)))
assertEquals(STRING_LENGTH, randomString.length)
}
@Test
fun givenAStringLength_whenUsingKotlin_thenReturnAlphanumericString() {
var randomString = (1..STRING_LENGTH).map { i -> kotlin.random.Random.nextInt(0, charPool.size) }
.map(charPool::get)
.joinToString("")
assert(randomString.matches(Regex(ALPHANUMERIC_REGEX)))
assertEquals(STRING_LENGTH, randomString.length)
}
@Test
fun givenAStringLength_whenUsingApacheCommon_thenReturnAlphanumericString() {
var randomString = RandomStringUtils.randomAlphanumeric(STRING_LENGTH)
assert(randomString.matches(Regex(ALPHANUMERIC_REGEX)))
assertEquals(STRING_LENGTH, randomString.length)
}
@Test
fun givenAStringLength_whenUsingRandomForBytes_thenReturnAlphanumericString() {
val random = SecureRandom()
val bytes = ByteArray(STRING_LENGTH)
random.nextBytes(bytes)
var randomString = (0..bytes.size - 1).map { i ->
charPool.get((bytes[i] and 0xFF.toByte() and (charPool.size-1).toByte()).toInt())
}.joinToString("")
assert(randomString.matches(Regex(ALPHANUMERIC_REGEX)))
assertEquals(STRING_LENGTH, randomString.length)
}
}

5
core-kotlin/src/test/resources/Kotlin.in
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@@ -1,5 +0,0 @@
Hello to Kotlin. Its:
1. Concise
2. Safe
3. Interoperable
4. Tool-friendly

2
core-kotlin/src/test/resources/Kotlin.out
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@@ -1,2 +0,0 @@
Kotlin
Concise, Safe, Interoperable, Tool-friendly