| 54 |
|
* programs. |
| 55 |
|
* |
| 56 |
|
* Because this class is in a different package than class Thread, |
| 57 |
< |
* field access methods must use Unsafe to bypass access control |
| 58 |
< |
* rules. The base functionality of Random methods is |
| 59 |
< |
* conveniently isolated in method next(bits), that just reads and |
| 60 |
< |
* writes the Thread field rather than its own field. However, to |
| 61 |
< |
* conform to the requirements of the Random constructor, during |
| 62 |
< |
* construction, the common static ThreadLocalRandom must maintain |
| 63 |
< |
* initialization and value fields, mainly for the sake of |
| 64 |
< |
* disabling user calls to setSeed while still allowing a call |
| 65 |
< |
* from constructor. For serialization compatibility, these |
| 66 |
< |
* fields are left with the same declarations as used in the |
| 67 |
< |
* previous ThreadLocal-based version of this class, that used |
| 68 |
< |
* them differently. Note that serialization is completely |
| 69 |
< |
* unnecessary because there is only a static singleton. But these |
| 70 |
< |
* mechanics still ensure compatibility across versions. |
| 57 |
> |
* field access methods use Unsafe to bypass access control rules. |
| 58 |
> |
* The base functionality of Random methods is conveniently |
| 59 |
> |
* isolated in method next(bits), that just reads and writes the |
| 60 |
> |
* Thread field rather than its own field. However, to conform to |
| 61 |
> |
* the requirements of the Random superclass constructor, the |
| 62 |
> |
* common static ThreadLocalRandom maintains an "initialized" |
| 63 |
> |
* field for the sake of rejecting user calls to setSeed while |
| 64 |
> |
* still allowing a call from constructor. Note that |
| 65 |
> |
* serialization is completely unnecessary because there is only a |
| 66 |
> |
* static singleton. But we generate a serial form containing |
| 67 |
> |
* "rnd" and "initialized" fields to ensure compatibility across |
| 68 |
> |
* versions. |
| 69 |
|
* |
| 70 |
< |
* Per-instance initialization is similar to that in the no-arg |
| 70 |
> |
* Per-thread initialization is similar to that in the no-arg |
| 71 |
|
* Random constructor, but we avoid correlation among not only |
| 72 |
|
* initial seeds of those created in different threads, but also |
| 73 |
|
* those created using class Random itself; while at the same time |
| 154 |
|
* @throws UnsupportedOperationException always |
| 155 |
|
*/ |
| 156 |
|
public void setSeed(long seed) { |
| 157 |
< |
if (initialized) // allow call from super() constructor |
| 157 |
> |
// only allow call from super() constructor |
| 158 |
> |
if (initialized) |
| 159 |
|
throw new UnsupportedOperationException(); |
| 160 |
|
} |
| 161 |
|
|
