Instantiation of TreeItem's (JavaFX)

Main.java

import javafx.scene.control.TreeItem;

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.HashMap;

public class Main {

    public static void main(String[] args) {
        int count = 1_000_000;

        Object[] o = new Object[count];
        try(StopWatch stopWatch = StopWatch.startNew("Instantiate Objects")) {
            for (int i = 0; i < count; i++) {
                o[i] = new Object();
            }
        }

        ArrayList[] a = (ArrayList[]) Array.newInstance(ArrayList.class, count);
        try(StopWatch stopWatch = StopWatch.startNew("Instantiate ArrayLists")) {
            for (int i = 0; i < count; i++) {
                a[i] = new ArrayList();
            }
        }

        HashMap[] hm = (HashMap[]) Array.newInstance(HashMap.class, count);
        try(StopWatch stopWatch = StopWatch.startNew("Instantiate HashMaps")) {
            for (int i = 0; i < count; i++) {
                hm[i] = new HashMap();
            }
        }

        TreeItem[] ti = (TreeItem[]) Array.newInstance(TreeItem.class, count);
        try(StopWatch stopWatch = StopWatch.startNew("Instantiate TreeItems")) {
            for (int i = 0; i < count; i++) {
                ti[i] = new TreeItem();
            }
        }

    }

}

STDOUT

Instantiate Objects: 0.12657099962234497 sec.
Instantiate ArrayLists: 0.19151298701763153 sec.
Instantiate HashMaps: 0.21388199925422668 sec.
Instantiate TreeItems: 11.619612693786621 sec.

StopWatch.java

import java.io.Closeable;

@SuppressWarnings("unused")
public class StopWatch implements Closeable {

    private String title;

    private long elapsedTime;
    private long startTime;
    private boolean started;

    private StopWatch(String title) {
        this.title = title;
    }

    public static StopWatch startNew(String title) {
        final StopWatch stopWatch = new StopWatch(title);
        stopWatch.start();
        return stopWatch;
    }

    public void start() {
        if (started) {
            return;
        }

        startTime = System.nanoTime();
        started = true;
    }

    public void reset() {
        elapsedTime = 0;
        startTime = System.nanoTime();
    }

    public void stop() {
        if (!started) {
            return;
        }

        started = false;
        elapsedTime += (System.nanoTime() - startTime);
    }

    public long getElapsedTime() {
        if (started) {
            return elapsedTime + (System.nanoTime() - startTime);
        }
        return elapsedTime;
    }

    public double getElapsedMilliseconds() {
        return getElapsedTime() / 1000000.0f;
    }

    public double getElapsedSeconds() {
        return getElapsedTime() / 1000000000.0f;
    }

    public String toString() {
        return title + ": " + getElapsedSeconds() + " sec.";
    }

    public long getStartTime() {
        return startTime;
    }

    public double getStartMilliseconds() {
        return getStartTime() / 1000000.0f;
    }

    public boolean isStarted() {
        return started;
    }

    public void close() {
        stop();

        System.out.println(this);
    }
}