BAEL-1402 code for the article: Try-with-resources in Kotlin (#3418)

core-kotlin/pom.xml

@@ -44,6 +44,11 @@
             <artifactId>kotlin-stdlib</artifactId>
             <version>${kotlin-stdlib.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib-jre8</artifactId>
+            <version>${kotlin-stdlib.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.jetbrains.kotlin</groupId>
             <artifactId>kotlin-test-junit</artifactId>

core-kotlin/src/test/kotlin/com/baeldung/kotlin/UseTest.kt

@@ -0,0 +1,67 @@
+package com.baeldung.kotlin
+
+import org.junit.Test
+import java.beans.ExceptionListener
+import java.beans.XMLEncoder
+import java.io.*
+import java.lang.Exception
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+import kotlin.test.fail
+
+class UseTest {
+
+    @Test
+    fun givenCloseable_whenUseIsCalled_thenItIsClosed() {
+        val stringWriter = StringWriter()
+        val writer = BufferedWriter(stringWriter) //Using a BufferedWriter because after close() it throws.
+        writer.use {
+            assertEquals(writer, it)
+
+            it.write("something")
+        }
+        try {
+            writer.write("something else")
+
+            fail("write() should have thrown an exception because the writer is closed.")
+        } catch (e: IOException) {
+            //Ok
+        }
+
+        assertEquals("something", stringWriter.toString())
+    }
+
+    @Test
+    fun givenAutoCloseable_whenUseIsCalled_thenItIsClosed() {
+        val baos = ByteArrayOutputStream()
+        val encoder = XMLEncoder(PrintStream(baos)) //XMLEncoder is AutoCloseable but not Closeable.
+                                                    //Here, we use a PrintStream because after close() it throws.
+        encoder.exceptionListener = ThrowingExceptionListener()
+        encoder.use {
+            assertEquals(encoder, it)
+
+            it.writeObject("something")
+        }
+        try {
+            encoder.writeObject("something else")
+            encoder.flush()
+
+            fail("write() should have thrown an exception because the encoder is closed.")
+        } catch (e: IOException) {
+            //Ok
+        }
+    }
+
+    @Test
+    fun whenSimpleFormIsUsed_thenItWorks() {
+        StringWriter().use { it.write("something") }
+    }
+}
+
+class ThrowingExceptionListener : ExceptionListener {
+    override fun exceptionThrown(e: Exception?) {
+        if(e != null) {
+            throw e
+        }
+    }
+}