add collection util

Author: shawndenggh

core/src/main/java/cn/vika/core/utils/CollectionUtil.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2021 vikadata
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+package cn.vika.core.utils;
+
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+/**
+ * Utils for Collection
+ * @author Shawn Deng
+ * @date 2021-05-19 23:52:38
+ */
+public class CollectionUtil {
+
+    /**
+     * Split collection by size using parallel stream
+     * @param list List
+     * @param splitSize split size
+     * @param <T> Class Type
+     * @return Split List Collection
+     */
+    public static <T> List<List<T>> splitListParallel(List<T> list, int splitSize) {
+        int limit = (list.size() + splitSize - 1) / splitSize;
+        return Stream.iterate(0, n -> n + 1)
+            .limit(limit).parallel().map(item ->
+                list.stream().skip((long) item * splitSize)
+                    .limit(splitSize).parallel()
+                    .collect(Collectors.toList()))
+            .collect(Collectors.toList());
+    }
+}