about bug: 8020216: Compile time error isn't shown when final class variable is not assigned

[John Rose]

On Aug 1, 2013, at 10:57 AM, Vicente-Arturo Romero-Zaldivar <vicente.romero at oracle.com> wrote:

> Is this what we want?

No.

For blank-final instance variables, the definite assignment is only required at *normal* completion of the constructor.  Abnormal completion (such as the throw in your example) *must* be allowed to happen when blank-finals are still unassigned.  Otherwise this code would fail:

class HasBlankF {
  final int hc;
  HasBlankF(Object x) {
    hc = x.hashCode();
  }
}

It would fail because there is a potential throw that works like this:

class HasBlankF {
  final int hc;
  HasBlankF(Object x) {
    if (x == null)  throw new NullPointerException();
    hc = x.hashCode();
  }
}

I added a comment to this effect on the bug report.

The same point applies for abnormal completion of <clinit> methods (static initializers).  Blank finals which are statics must be definitely assigned at normal termination of the last static initializer.  If a static initializer terminates abnormally, the class is not available to its users, and some of its blank finals may validly remain forever uninitialized.

— John
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