Kotlin conversion: Optional

sop-java/src/main/java/sop/util/Optional.java

@@ -1,50 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package sop.util;
-
-/**
- * Backport of java.util.Optional for older Android versions.
- *
- * @param <T> item type
- */
-public class Optional<T> {
-
-    private final T item;
-
-    public Optional() {
-        this(null);
-    }
-
-    public Optional(T item) {
-        this.item = item;
-    }
-
-    public static <T> Optional<T> of(T item) {
-        if (item == null) {
-            throw new NullPointerException("Item cannot be null.");
-        }
-        return new Optional<>(item);
-    }
-
-    public static <T> Optional<T> ofNullable(T item) {
-        return new Optional<>(item);
-    }
-
-    public static <T> Optional<T> ofEmpty() {
-        return new Optional<>(null);
-    }
-
-    public T get() {
-        return item;
-    }
-
-    public boolean isPresent() {
-        return item != null;
-    }
-
-    public boolean isEmpty() {
-        return item == null;
-    }
-}

sop-java/src/main/kotlin/sop/util/Optional.kt

@@ -0,0 +1,26 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package sop.util
+
+/**
+ * Backport of java.util.Optional for older Android versions.
+ *
+ * @param <T> item type
+ */
+data class Optional<T>(val item: T? = null) {
+
+    val isPresent: Boolean = item != null
+    val isEmpty: Boolean = item == null
+
+    fun get() = item
+
+    companion object {
+        @JvmStatic fun <T> of(item: T) = Optional(item!!)
+
+        @JvmStatic fun <T> ofNullable(item: T?) = Optional(item)
+
+        @JvmStatic fun <T> ofEmpty() = Optional(null as T?)
+    }
+}