import sun.misc.*;

public class UnsafeTester {
  private static final Unsafe unsafe = Unsafe.getUnsafe();
  public static void main(String[] args) {
    long ptr = unsafe.allocateMemory(512);
    try{
      unsafe.putChar(ptr,'a');
      unsafe.putChar(ptr,'b');
      System.out.println("Unsafe: " + unsafe.toString());
    }
    finally{
      unsafe.freeMemory(ptr);
    }
  }
}

java.lang.ExceptionInInitializerError
Caused by: java.lang.SecurityException: Unsafe
      at sun.misc.Unsafe.getUnsafe(Unsafe.java:68)
      at garbage.UnsafeTester.<clinit>(UnsafeTester.java:8)
Exception in thread "main"