8283346: Optimize observable ArrayList creation in FXCollections

Reviewed-by: mstrauss, nlisker, kcr

Author: Marius Hanl

modules/javafx.base/src/main/java/javafx/collections/FXCollections.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2010, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -347,9 +347,7 @@ public static <E> ObservableList<E> observableArrayList(Callback<E, Observable[]
      * @see #observableArrayList()
      */
     public static <E> ObservableList<E> observableArrayList(E... items) {
-        ObservableList<E> list = observableArrayList();
-        list.addAll(items);
-        return list;
+        return observableList(new ArrayList<>(Arrays.asList(items)));
     }
 
     /**
@@ -360,9 +358,7 @@ public static <E> ObservableList<E> observableArrayList(E... items) {
      * @return a newly created observableArrayList
      */
     public static <E> ObservableList<E> observableArrayList(Collection<? extends E> col) {
-        ObservableList<E> list = observableArrayList();
-        list.addAll(col);
-        return list;
+        return observableList(new ArrayList<>(col));
     }
 
     /**

modules/javafx.base/src/test/java/test/javafx/collections/FXCollectionsTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -42,6 +42,47 @@
 
 public class FXCollectionsTest {
 
+    @Test
+    public void testCreateObservableArrayListFromArray() {
+        ObservableList<String> observableList = FXCollections.observableArrayList("1", "2", null);
+
+        assertEquals(3, observableList.size());
+        assertTrue(observableList.contains("1"));
+        assertTrue(observableList.contains("2"));
+        assertTrue(observableList.contains(null));
+    }
+
+    @Test
+    public void testCreateObservableArrayListFromCollection() {
+        List<String> list = Arrays.asList("1", "2", null);
+        ObservableList<String> observableList = FXCollections.observableArrayList(list);
+
+        assertEquals(3, observableList.size());
+        assertTrue(observableList.contains("1"));
+        assertTrue(observableList.contains("2"));
+        assertTrue(observableList.contains(null));
+    }
+
+    @Test
+    public void testCreateObservableArrayListWithNullCollection() {
+        assertThrows(NullPointerException.class, () -> FXCollections.observableArrayList((Collection<Object>) null));
+    }
+
+    @Test
+    public void testCreateObservableArrayListWithNullArray() {
+        assertThrows(NullPointerException.class, () -> FXCollections.observableArrayList((Object[]) null));
+    }
+
+    @Test
+    public void testCreateObservableArrayListDoesNotModifyOriginalCollection() {
+        List<String> list = List.of("1", "2", "3");
+        ObservableList<String> observableList = FXCollections.observableArrayList(list);
+        observableList.add("4");
+
+        assertEquals(4, observableList.size());
+        assertEquals(3, list.size());
+    }
+
     @Test
     @SuppressWarnings("unchecked")
     public void concatTest() {