Sun's Unsafe Class

Question

First up I'm wondering why we aren't allowed to use this class. That is how they got all the buffer's to work in NIO without making JNI calls. Second question is why is there no source code or documentation on this class. My third question is, is there anyone that know how to use this class? I'm getting a security exception when I try and run my code. I'll post the code if anyone wants to see it. Thanks for anyone's help.

Answer 1

I wrote this little hack to experiment with Unsafe, have fun!
import sun.misc.Unsafe;
import java.lang.reflect.Field;
public class UnsafeDemo {
public static void main(String[] args) throws Exception {
  Unsafe unsafe = getUnsafe();
  System.out.println("Unsafe = " + unsafe);
  System.out.println("  addressSize() = " + unsafe.addressSize());
  System.out.println("  pageSize() = " + unsafe.pageSize());
  System.out.println("  pageSize() = " + unsafe.pageSize());
  unsafe.putByte((long)0xa000, (byte)47);
public static Unsafe getUnsafe() throws Exception {
  Unsafe unsafe = null;
  try {
   Class uc = Unsafe.class;
   Field[] fields = uc.getDeclaredFields();
   for (int i = 0; i < fields.length; i++) {
    if (fields.getName().equals("theUnsafe")) {
fields[i].setAccessible(true);
unsafe = (Unsafe) fields[i].get(uc);
break;
catch (Exception ignore) {}
return unsafe;