[ nice-Bugs-1624383 ] A case where nullness inference doesn't quite work

Bugs item #1624383, was opened at 2006-12-29 07:11
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: A case where nullness inference doesn't quite work

Initial Comment:
If you do the following, the nullness inference fails unless you add an assertion:

?Foo bar = null;
bar = myMethod();
doStuff(bar);

Where 

public Foo myMethod();
public void doStuff(Foo foo);

The compiler things that foo might be null, and so you can't call doStuff on it. 

At least that's what I think is happening. Here's the sample code which this appeared in:

package kakuro;
import java.util.*;
import java.lang.ref.*;

public class CalculationTable<S, T>
{
    private HashMap<S, ?SoftReference<T>> values = new HashMap();
    private (S -> T) calculate;

    public T get(S arg)
    {
        ?SoftReference<T> valueRef = values.get(arg);
        ?T value;

        if (valueRef == null)
        {
            value = calculate(arg);
        }
        else
        {
            value = valueRef.get();
        }

        if (value == null)
        {
            value = calculate(arg);
            values.put(arg, new SoftReference(value));
        }

        return value;
    }
}

The error occurs with the "new SoftReference(value)".

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