EVALUATION

As there is no spec or implementation issue with Random, and a seperate CR has been opened for the tests that made the invalid assumption, I hereby commandeer this CR for the remaining issue in ThreadLocalRandom - the synopsis has been changed accordingly.
                                     

EVALUATION

Changeset: 1db252f307b6
Author:    martin
Date:      2010-06-02 17:53 -0700
URL:       http://hg.openjdk.java.net/jdk7/tl/jdk/rev/1db252f307b6

6955840: ThreadLocalRandom bug - overriden setSeed(long) method is not invoked for java.util.Random(long)
Summary: Allow setSeed only during construction
Reviewed-by: dl, dholmes

! src/share/classes/java/util/concurrent/ThreadLocalRandom.java
                                     

EVALUATION

java.util.concurrent.ThreadLocalRandom.setSeed(long seed) does not throw UnsupportedOperationException due to wrong assumption that the setSeed method will be invoked as part of the java.util.Random constructors call.
                                     

SUGGESTED FIX

Martin Buchholz suggests:

diff --git a/src/share/classes/java/util/concurrent/ThreadLocalRandom.java
b/src/share/classes/java/util/concurrent/ThreadLocalRandom.java
--- a/src/share/classes/java/util/concurrent/ThreadLocalRandom.java
+++ b/src/share/classes/java/util/concurrent/ThreadLocalRandom.java
@@ -73,10 +73,10 @@
     private long rnd;

     /**
-     * Initialization flag to permit the first and only allowed call
-     * to setSeed (inside Random constructor) to succeed.  We can't
-     * allow others since it would cause setting seed in one part of a
-     * program to unintentionally impact other usages by the thread.
+     * Initialization flag to permit calls to setSeed to succeed only
+     * while executing the Random constructor.  We can't allow others
+     * since it would cause setting seed in one part of a program to
+     * unintentionally impact other usages by the thread.
      */
     boolean initialized;

@@ -98,11 +98,10 @@

     /**
      * Constructor called only by localRandom.initialValue.
-     * We rely on the fact that the superclass no-arg constructor
-     * invokes setSeed exactly once to initialize.
      */
     ThreadLocalRandom() {
         super();
+        initialized = true;
     }

     /**
@@ -123,7 +122,6 @@
     public void setSeed(long seed) {
         if (initialized)
             throw new UnsupportedOperationException();
-        initialized = true;
         rnd = (seed ^ multiplier) & mask;
     }
                                     

EVALUATION

The following JCK7 tests:
  api/java_util/Random/index.html#Random[Random2002,Random2004]
are invalid because they incorrectly assume that the setSeed method will be invoked as part of the Random(long) constructor call.
                                     

EVALUATION

When it says "is equivalent to" this refers to the methods of the current class, not to any methods of a derived class. There is no requirement, nor should there be any expectation, that the setSeed method is actually invoked as part of the constructor. For example, a common implementation pattern for "equivalent" code would do:

    public Random(long seed) {
       ...
       setSeedInternal(seed);
    }
 
    public void setSeed(long seed) {
       setSeedInternal(seed);
    }

    private setSeedInternal(long seed) { ... }

Any class that overrides setSeed should not expect it to be invoked as part of the constructor. Any test that makes this assumption is invalid in my view.