import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.IntStream;
import com.sun.management.ThreadMXBean;


public class Main {
    private final static ThreadMXBean threadMgmt = getSunThreadMxBean();

    public static long getMemoryAllocated(Thread thread) {
        if (threadMgmt == null) {
            return -1;
        } else {
            return threadMgmt.getThreadAllocatedBytes(thread.getId());
        }
    }

    private static ThreadMXBean getSunThreadMxBean() {
        try {
            // original bean is from j.l.m package (interface), but actually it's Sun's extension
            return (ThreadMXBean) ManagementFactory.getThreadMXBean();
        } catch (ClassCastException fail) {
            return null;
        }
    }

    public static void main(String[] args) throws IOException, InterruptedException {
        Thread.sleep(10_000);
        System.out.println(getMemoryAllocated(Thread.currentThread()));
        int[] ints = IntStream.range(0, Integer.MAX_VALUE >> 1).toArray();
        System.out.println(ints.length);
        System.out.println(getMemoryAllocated(Thread.currentThread()));
        ints = null;
        System.gc();
        System.out.println(getMemoryAllocated(Thread.currentThread()));
        Thread.sleep(10_000);
        String s = "";
        for (int i = 0; i < 10_000; i++) {
            s += i;
        }
        System.out.println(getMemoryAllocated(Thread.currentThread()));
        System.out.println(s);
        System.out.println(getMemoryAllocated(Thread.currentThread()));
    }
}