public class HeapSizeCheck {
    public static void main(String[] args) {
        Runtime runtime = Runtime.getRuntime();
        long mib = 1024 * 1024;
        System.out.printf("initial heap (MiB): %d%n", runtime.totalMemory() / mib);
        System.out.printf("maximum heap (MiB): %d%n", runtime.maxMemory() / mib);
    }
}