这个嵌套循环是执行此任务的最快选项吗？

Question

代码的第一部分创建一个随机的arrayList。 方法1是传统的＆＃34;嵌套循环的方法。 方法2删除未在arrayList2Temp中找到的元素，以便在下一次迭代中保存一个比较。从理论上讲，后一种方法应该更快，但事实并非如此。我在代码中构建了一个秒表，因此它输出执行每个方法所需的时间（以毫秒为单位）。最后一部分是一致性检查，以确保每个方法确实创建相同的结果。我应该使用嵌套的数组列表吗？并行执行此任务的正确方法是什么，即不必迭代每个元素？在任何情况下，我都会对能够减少几毫秒的任何建议感到高兴。

Delete4

    package delete4;

    import java.util.ArrayList;
    import java.util.Random;

    /**
    *
    * @author
    */
    public class Delete4 {

        /**
         * @param args the command line arguments
         */
        public static void main(String[] args) {
            //create random arrayList
            Random rand = new Random();
            int Recipient = 0;
            int list0ItemCount = 5000;
            int Score = 0;
            ArrayList<Class1> arrayList0 = new ArrayList<>();
            for (int i = 0; i < list0ItemCount; i++) {
                Recipient = rand.nextInt((100000 - 1) + 1) + 1;
                while (Recipient == i) {
                    Recipient = rand.nextInt((100000 - 1) + 1) + 1;
                }
                Score = rand.nextInt((10 + 10) + 1) - 10;
                arrayList0.add(new Class1(i, Recipient, Score, Score));
            }
            double startTime;
            double endTime;
            double duration = 0;
            //method 1
            startTime = System.nanoTime();
            ArrayList<Class1> arrayList1 = new ArrayList<>(arrayList0);
            ArrayList<Class1> arrayList1Temp = new ArrayList<>(arrayList0);
            int list1ItemCount = arrayList1.size();
            int list1TempItemCount = arrayList1.size();
            for (int i = 0; i < list1ItemCount; i++) {
                for (int j = 0; j < list1TempItemCount; j++) {
                    if (arrayList1.get(i).Recipient == arrayList1Temp.get(j).Recipient && arrayList1.get(i).ID != arrayList1Temp.get(j).ID) {
                        arrayList1.set(i, new Class1(arrayList1.get(i).ID, arrayList1.get(i).Recipient, arrayList1.get(i).Score, arrayList1.get(i).CumulativeScore + arrayList1Temp.get(j).Score));
                    }
                }
            }
            endTime = System.nanoTime();
            duration = (endTime - startTime) / 1000000;
            System.out.println(duration);
            //method 2
            startTime = System.nanoTime();
            ArrayList<Class1> arrayList2 = new ArrayList<>(arrayList0);
            ArrayList<Class1> arrayList2Temp = new ArrayList<>(arrayList0);
            int list2ItemCount = arrayList2.size();
            int list2TempItemCount = arrayList2Temp.size();
            for (int i = 0; i < list2ItemCount; i++) {
                boolean found = false;
                int k = 0;
                for (int j = 0; j < list2TempItemCount; j++) {
                    if (arrayList2.get(i).Recipient == arrayList2Temp.get(j).Recipient && arrayList2.get(i).ID != arrayList2Temp.get(j).ID) {
                        arrayList2.set(i, new Class1(arrayList2.get(i).ID, arrayList2.get(i).Recipient, arrayList2.get(i).Score, arrayList2.get(i).CumulativeScore + arrayList2Temp.get(j).Score));
                        found = true;
                    }
                    if (arrayList2.get(i).Recipient == arrayList2Temp.get(j).Recipient && arrayList2.get(i).ID == arrayList2Temp.get(j).ID) {
                        k = j;
                    }
                }
                if (found == false) {
                    arrayList2Temp.remove(k);
                    list2TempItemCount = arrayList2Temp.size();
                }
            }
            endTime = System.nanoTime();
            duration = (endTime - startTime) / 1000000;
            System.out.println(duration);
            //consistency check
            for (int i = 0; i < list0ItemCount; i++) {
                if (arrayList2.get(i).ID != arrayList1.get(i).ID ||
                    arrayList2.get(i).Recipient != arrayList1.get(i).Recipient ||
                    arrayList2.get(i).Score != arrayList1.get(i).Score ||
                    arrayList2.get(i).CumulativeScore != arrayList1.get(i).CumulativeScore) {
                    System.out.println("error1");
                }
            } 
        }

    }

的Class1

    package delete4;

    /**
     *
     * @author
     */
    public class Class1 {
        int ID;
        int Recipient;
        int Score;
        int CumulativeScore;
        Class1(int ID, int Recipient, int Score, int CumulativeScore) {
            this.ID = ID;
            this.Recipient = Recipient;
            this.Score = Score;
            this.CumulativeScore = CumulativeScore;
        }
    }