SoftReference operation synchronization detail

The following may have more apparent effect when using a WeakReference.
Suppose I initialize a class member field which is a SoftReference, at
some point:

SoftReference cache = new SoftReference(obj);

Then I have the following code accessing the referenced object, in a
method body:

Object obj = null;
if (cache != null) {
obj = cache.get();
}
if (obj == null) {
obj = new Object(); /* re-initialize obj */
cache = new SoftReference(obj);
}
/* do with obj */

Is it guaranteed the 'cache' won't be cleared after the 'if (cache !=
null)' evaluates to true and prior executing the first statement in the
'if' block?

Is it guaranteed 'Reference.get()' will return a non-null result if the
corresponding SoftReference or WeakReference is not cleared yet?, so I
could go without the explicit 'obj = null' initialization in the above
example:

Object obj;
if (cache != null) {
obj = cache.get();
} else {
obj = new Object(); /* re-initialize obj */
cache = new SoftReference(obj);
}
/* do with obj */

--
Stanimir

.

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