feat: add functionality to split a list into sub lists of specified size

2025-03-23 12:57:29 +08:00
parent f3e6e70f75
commit d33176a0ee
1 changed files with 72 additions and 0 deletions
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2024-2025 OnixByte.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.onixbyte.devkit.utils;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A utility class for splitting a List into multiple sub lists, where each sublist has a maximum
+ * number of elements specified by the user.
+ *
+ * @author siujamo
+ */
+public final class ListUtil {
+
+    /**
+     * Splits a given List into a List of sub lists, where each sublist contains at most
+     * {@code maxSize} elements. The original list is not modified, and new sub lists are created
+     * to hold the partitioned data.
+     * <p>
+     * If the original list's size is less than or equal to {@code maxSize}, a single sublist
+     * containing all elements is returned. If the list is empty, an empty list of sub lists
+     * is returned.
+     *
+     * @param <T>          the type of elements in the list
+     * @param originalList the list to be split, must not be null
+     * @param maxSize      the maximum number of elements in each sublist, must be positive
+     * @return a List of sub lists, where each sublist has at most {@code maxSize} elements
+     * @throws IllegalArgumentException if {@code originalList} is null or {@code maxSize} is less
+     *                                  than or equal to 0
+     */
+    public static <T> List<List<T>> splitList(List<T> originalList, int maxSize) {
+        // check input
+        if (originalList == null || maxSize <= 0) {
+            throw new IllegalArgumentException("List cannot be null and maxSize must be positive");
+        }
+
+        var result = new ArrayList<List<T>>();
+        var size = originalList.size();
+
+        // if the original list is empty or smaller than maxSize, return it as a single sublist
+        if (size <= maxSize) {
+            result.add(new ArrayList<>(originalList));
+            return result;
+        }
+
+        // split the list
+        for (var i = 0; i < size; i += maxSize) {
+            var end = Math.min(i + maxSize, size); // ensure not to exceed list length
+            List<T> subList = originalList.subList(i, end);
+            result.add(new ArrayList<>(subList)); // create a new list to avoid reference issues
+        }
+
+        return result;
+    }
+
+}