direct access memory location in java

import java.lang.reflect.Field;
 
import sun.misc.Unsafe;
 
public class Direct {
 
    public static void main(String... args) {
        Unsafe unsafe = null;
 
        try {
            Field field = sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
            field.setAccessible(true);
            unsafe = (sun.misc.Unsafe) field.get(null);
        } catch (Exception e) {
            throw new AssertionError(e);
        }
 
        long value = 12345;
        byte size = 8; // a long is 64 bits (http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html)
        long allocateMemory = unsafe.allocateMemory(size);
        unsafe.putLong(allocateMemory, value);
        long readValue = unsafe.getLong(allocateMemory);
        System.out.println("read value : " + readValue);
 
    }
}