Java Thread speed comparison

import java.util.Random;

public class Main {

    public static volatile long start;
    public static volatile long end;
    public static void main(String[] args) {

        Random r = new Random();
        int[] testArray1 = new int[100000];
        int[] testArray2 = new int[100000];
        int[] testArray3 = new int[100000];
        int[] testArray4 = new int[100000];
        for (int i = 0; i < testArray1.length; i++) {
            testArray1[i] = r.nextInt(100000);
            testArray2[i] = testArray1[i];
            testArray3[i] = testArray1[i];
            testArray4[i] = testArray1[i];
        }


        Thread t1 = new Thread(() -> {
            InsertionSort(testArray1);
            if(end == 0){
                end = 999;
            } else {
                end = System.currentTimeMillis();
                System.out.println(end - start);
            }

        });
        Thread t2 = new Thread(() -> {
            BubbleSort(testArray2);
            if(end == 0){
                end = 999;
            } else {
                end = System.currentTimeMillis();
                System.out.println(end - start);
            }

        });

        start = System.currentTimeMillis();

        InsertionSort(testArray3);
        BubbleSort(testArray4);

        end = System.currentTimeMillis();


        System.out.println("Thread nélkül: ");
        System.out.println(end - start);

        System.out.println("\nThreaddel:");
        end = 0;
        start = System.currentTimeMillis();

        t1.start();
        t2.start();




    }

    public static void InsertionSort(int[] data) {
        for (int i = 0; i < data.length - 1; i++) {
            for (int j = i + 1; j > 0; j--) {
                if (data[j - 1] < data[j]) {
                    int temp = data[j - 1];
                    data[j - 1] = data[j];
                    data[j] = temp;
                }
            }
        }
    }

    public static void BubbleSort(int[] data) {
        for (int i = 0; i < data.length; i++) {
            for (int j = 1; j < (data.length - i); j++) {
                if (data[j - 1] < data[j]) {
                    //swap elements
                    int temp = data[j - 1];
                    data[j - 1] = data[j];
                    data[j] = temp;
                }
            }
        }
    }


}