From f47a5ebfdb543074a379836a4e887a65b186beb8 Mon Sep 17 00:00:00 2001
From: leewyatt <leewyatt7788@gmail.com>
Date: Fri, 24 May 2024 21:17:32 +0900
Subject: [PATCH] Enhancement: If there are a large number of elements, using
 replaceAll may cause performance issues.

---
 .../com/dlsc/gemsfx/MultiColumnListView.java  | 31 ++--------
 .../java/com/dlsc/gemsfx/util/ListUtils.java  | 61 +++++++++++++++++++
 2 files changed, 66 insertions(+), 26 deletions(-)
 create mode 100644 gemsfx/src/main/java/com/dlsc/gemsfx/util/ListUtils.java

diff --git a/gemsfx/src/main/java/com/dlsc/gemsfx/MultiColumnListView.java b/gemsfx/src/main/java/com/dlsc/gemsfx/MultiColumnListView.java
index 4c24338a..2abc7e7b 100644
--- a/gemsfx/src/main/java/com/dlsc/gemsfx/MultiColumnListView.java
+++ b/gemsfx/src/main/java/com/dlsc/gemsfx/MultiColumnListView.java
@@ -1,6 +1,7 @@
 package com.dlsc.gemsfx;
 
 import com.dlsc.gemsfx.skins.MultiColumnListViewSkin;
+import com.dlsc.gemsfx.util.ListUtils;
 import javafx.beans.InvalidationListener;
 import javafx.beans.property.BooleanProperty;
 import javafx.beans.property.ListProperty;
@@ -346,13 +347,7 @@ public ColumnListCell(MultiColumnListView<T> multiColumnListView) {
 
                 multiColumnListView.getDraggedItems().setAll(getListView().getSelectionModel().getSelectedItems());
 
-                getListView().getItems().replaceAll(item -> {
-                    if (item == getItem()) {
-                        return multiColumnListView.getPlaceholderFrom();
-                    }
-
-                    return item;
-                });
+                ListUtils.updateFirstMatching(getListView().getItems(), item -> item == getItem(), multiColumnListView.getPlaceholderFrom());
             });
 
             setOnDragOver(event -> {
@@ -395,13 +390,7 @@ public ColumnListCell(MultiColumnListView<T> multiColumnListView) {
                 items.remove(multiColumnListView.getPlaceholderFrom());
 
                 T draggedItem = multiColumnListView.getDraggedItem();
-                items.replaceAll(item -> {
-                    if (item == multiColumnListView.getPlaceholderTo()) {
-                        return draggedItem;
-                    }
-
-                    return item;
-                });
+                ListUtils.updateFirstMatching(items, item -> item == multiColumnListView.getPlaceholderTo(), draggedItem);
 
                 if (!items.contains(draggedItem)) {
                     // probably dropped on same list view / same column (hence no "to" placeholder)
@@ -423,24 +412,14 @@ public ColumnListCell(MultiColumnListView<T> multiColumnListView) {
                         getListView().getItems().removeIf(item -> item == multiColumnListView.getPlaceholderFrom());
                     } else {
                         log("   drop was not completed, replacing placeholder with dragged item");
-                        getListView().getItems().replaceAll(item -> {
-                            if (item == multiColumnListView.getPlaceholderFrom()) {
-                                return multiColumnListView.getDraggedItem();
-                            }
-                            return item;
-                        });
+                        ListUtils.updateFirstMatching(getListView().getItems(), item -> item == multiColumnListView.getPlaceholderFrom(), multiColumnListView.getDraggedItem());
                     }
                 } else {
                     log("drag done, not accepted");
 
                     // put the item back into the "from" location
                     log("putting item back into 'from' location");
-                    getListView().getItems().replaceAll(item -> {
-                        if (item == multiColumnListView.getPlaceholderFrom()) {
-                            return multiColumnListView.getDraggedItem();
-                        }
-                        return item;
-                    });
+                    ListUtils.updateFirstMatching(getListView().getItems(), item -> item == multiColumnListView.getPlaceholderFrom(), multiColumnListView.getDraggedItem());
                 }
 
                 multiColumnListView.setDraggedItem(null);
diff --git a/gemsfx/src/main/java/com/dlsc/gemsfx/util/ListUtils.java b/gemsfx/src/main/java/com/dlsc/gemsfx/util/ListUtils.java
new file mode 100644
index 00000000..8f353cab
--- /dev/null
+++ b/gemsfx/src/main/java/com/dlsc/gemsfx/util/ListUtils.java
@@ -0,0 +1,61 @@
+package com.dlsc.gemsfx.util;
+
+import java.util.List;
+import java.util.ListIterator;
+import java.util.function.Predicate;
+
+public class ListUtils {
+
+    /**
+     * Update matching elements in the list with the provided new value.
+     *
+     * @param list                 the list to operate on
+     * @param matchPredicate       the predicate to match elements
+     * @param newValue             the new value to replace matching elements
+     * @param breakAfterFirstMatch whether to break after the first match
+     * @param <T>                  the type of elements in the list
+     * @return the number of elements updated
+     */
+    public static <T> int updateMatching(List<T> list, Predicate<T> matchPredicate, T newValue, boolean breakAfterFirstMatch) {
+        int updateCount = 0;
+        ListIterator<T> iterator = list.listIterator();
+        while (iterator.hasNext()) {
+            T currentElement = iterator.next();
+            if (matchPredicate.test(currentElement)) {
+                iterator.set(newValue);
+                updateCount++;
+                if (breakAfterFirstMatch) {
+                    break;
+                }
+            }
+        }
+        return updateCount;
+    }
+
+    /**
+     * Update the first matching element in the list with the provided new value.
+     *
+     * @param list           the list to operate on
+     * @param matchPredicate the predicate to match elements
+     * @param newValue       the new value to replace matching elements
+     * @param <T>            the type of elements in the list
+     * @return the number of elements updated
+     */
+    public static <T> int updateFirstMatching(List<T> list, Predicate<T> matchPredicate, T newValue) {
+        return updateMatching(list, matchPredicate, newValue, true);
+    }
+
+    /**
+     * Update all matching elements in the list with the provided new value.
+     *
+     * @param list           the list to operate on
+     * @param matchPredicate the predicate to match elements
+     * @param newValue       the new value to replace matching elements
+     * @param <T>            the type of elements in the list
+     * @return the number of elements updated
+     */
+    public static <T> int updateAllMatching(List<T> list, Predicate<T> matchPredicate, T newValue) {
+        return updateMatching(list, matchPredicate, newValue, false);
+    }
+}
+