Memory usage of sorts

MemoryUsage

package lect;

public class MemoryUsage {
	
    private static final long MEGABYTE = 1024L * 1024L;
    private static final long KILOBYTE = 1024L;
    
    public static long bytesToKilobytes(long bytes) {
        return bytes / KILOBYTE;
    }
    
    public static long bytesToMegabytes(long bytes) {
        return bytes / MEGABYTE;
    }
    
    public static void main(String[] args) {
        
    	MyLinkedList<Integer> list = new MyLinkedList<Integer>();
	for (int i = 0; i < 10000; i++) {
		list.add((int)Math.random()*100);
	}
	selectionSort(list);
        Runtime runtime = Runtime.getRuntime();
        runtime.gc();
        long memory = runtime.totalMemory() - runtime.freeMemory();
        System.out.println("---My Linked List Selection Sort---");
        System.out.println("Used memory is bytes: " + memory);
        System.out.println("Used memory is megabytes: " + bytesToMegabytes(memory));
        System.out.println("Used memory is kilobytes: " + bytesToKilobytes(memory));

        
        
        MyArrayList<Integer> arraylist = new MyArrayList<Integer>();
	for (int i = 0; i < 1000; i++) {
		arraylist.add((int)Math.random()*100);
	}
	selectionSort(arraylist);
        runtime = Runtime.getRuntime();
        runtime.gc();
        memory = runtime.totalMemory() - runtime.freeMemory();
        System.out.println("---My Array List Selection Sort---");
        System.out.println("Used memory is bytes: " + memory);
        System.out.println("Used memory is megabytes: " + bytesToMegabytes(memory));
        System.out.println("Used memory is kilobytes: " + bytesToKilobytes(memory));
        
        
        MyLinkedList<Integer> arr = new MyLinkedList<Integer>();
        for (int i = 0; i < 1000; i++) {
            arr.add((int)Math.random()*100);
        }
        insertSort(arr);
        runtime = Runtime.getRuntime();
        runtime.gc();
        memory = runtime.totalMemory() - runtime.freeMemory();
        System.out.println("---My Linked List Insertion Sort---");
        System.out.println("Used memory is bytes: " + memory);
        System.out.println("Used memory is megabytes: " + bytesToMegabytes(memory));
        System.out.println("Used memory is kilobytes: " + bytesToKilobytes(memory));
        
        
        MyArrayList<Integer> array = new MyArrayList<Integer>();
        for (int i = 0; i < 1000; i++) {
            array.add((int)Math.random()*100);
        }
        insertSorta(array);
        runtime = Runtime.getRuntime();
        runtime.gc();
        memory = runtime.totalMemory() - runtime.freeMemory();
        System.out.println("---My Array List Insertion Sort---");
        System.out.println("Used memory is bytes: " + memory);
        System.out.println("Used memory is megabytes: " + bytesToMegabytes(memory));
        System.out.println("Used memory is kilobytes: " + bytesToKilobytes(memory));
    }
    
	public static void selectionSort(MyAbstractList<Integer> list) {
		int n = list.size;
		Integer temp;
		for (int index = 0; index < n; index++) {
			int min = index;
			for (int j = index+1; j < n; j++) {
				if (list.get(j) < list.get(min)) {
					min = j;
				}
			}
			temp = list.get(index);
			list.set(index, list.get(min));
			list.set(min, temp);
		}
	}
        
        
        public static void insertSort(MyLinkedList<Integer> list) {
            for(int i = 0; i <= list.size(); i++) {
                for(int lastIndex = i-1; lastIndex > 0; lastIndex--){
                    if(list.get(lastIndex) < list.get(lastIndex-1)) {
                        int value = list.get(lastIndex);
                        list.set(lastIndex, list.get(lastIndex-1));
                        list.set(lastIndex-1, value);
                    } else
                        break;
                }
            }
        }
        
        public static void insertSorta(MyArrayList<Integer> list) {
        for(int index = 0; index <= list.size(); index++) {
            for(int lastIndex = index-1; lastIndex > 0; lastIndex--){
                if(list.get(lastIndex) < list.get(lastIndex-1)) {
                    int value = list.get(lastIndex);
                    list.set(lastIndex, list.get(lastIndex-1));
                    list.set(lastIndex-1, value);
                } else
                    break;
            }
        }
    }
}