RFR: 8279598: Provide adapter from RandomGenerator to Random

[Roger Riggs]

On Sat, 8 Jan 2022 21:00:37 GMT, Yasser Bazzi <duke at openjdk.java.net> wrote:

> Hi, could i get a review on this implementation proposed by Stuart Marks, i decided to use the https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/random/RandomGenerator.html interface to create the default method `asRandom()` that wraps around the newer algorithms to be used on classes that do not accept the new interface.
> 
> Some things to note as proposed by the bug report, the protected method next(int bits) is not overrided and setSeed() method if left blank up to discussion on what to do with it.
> 
> Small test done on https://gist.github.com/YShow/da678561419cda8e32fccf3a27a649d4

src/java.base/share/classes/java/util/random/RandomGenerator.java line 144:

> 142:     /**
> 143:      * Returns a wrapper to use {@link java.util.Random}
> 144:      * @return {@link java.util.Random}

Possible reword:
"Returns a Random from this RandomGenerator."

It should be specified that the resulting Random acts in all respects except that
setSeed is not available.

Missing period at the end of the sentence.  Check all comments for grammar and punctuation.

src/java.base/share/classes/jdk/internal/util/random/RandomWrapper.java line 41:

> 39: @SuppressWarnings("serial")
> 40: public class RandomWrapper extends Random implements RandomGenerator {
> 41:     private final RandomGenerator randomToWrap;

Does this class need to be public? It acts as Random in almost all respects.

src/java.base/share/classes/jdk/internal/util/random/RandomWrapper.java line 58:

> 56:      * setSeed does not exist in {@link java.util.random.RandomGenerator} so can't
> 57:      * use it
> 58:      */

Its debatable whether setSeed can ignore the argument or should throw an exception.
If it ignores the argument, it is explicitly violating the contract of the supertype Random.setSeed
that says the seed is set.  
I'd recommend throwing an UnsupportedOperationException because setSeed will not work as expected.
Other classes (ThreadLocalRandom) throws UnsupportedOperationException from setSeed.

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PR: https://git.openjdk.java.net/jdk/pull/7001