Testpublic class Test extends Object
| Fields Summary |
|---|
| private static Vector | canonicalIntegers |
| Methods Summary |
|---|
| public static java.lang.Integer | getCanonicalInteger(int i)
//First make sure our collection is big enough
if (i >= canonicalIntegers.size())
canonicalIntegers.setSize(i+1);
//Now access the canonical value.
//This element contains null if the the value has never been set
//or a weak reference that may have been garbage collected
WeakReference ref = (WeakReference) canonicalIntegers.elementAt(i);
Integer canonical_i;
if (ref == null)
{
//never been set, so create and set it now
canonical_i = new Integer(i);
canonicalIntegers.setElementAt(new WeakReference(canonical_i), i);
}
else if( (canonical_i = (Integer) ref.get()) == null)
{
//has been set, but was garbage collected, so recreate and set it now
//Include a print to see that we are resetting the Integer
System.out.println("Resetting integer " + i);
canonical_i = new Integer(i);
canonicalIntegers.setElementAt(new WeakReference(canonical_i), i);
}
//else clause not needed, since the alternative is that the weak ref was
//present and not garbage collected, so we now have our canonical integer
return canonical_i;
| | public static void | main(java.lang.String[] args)
try
{
Integer ic = null;
int REPEAT = args.length > 0 ? Integer.parseInt(args[0]) : 10000000;
//Hang on to the Integer objects from 3 to 7
//so that they cannot be garbage collected
Integer i3 = getCanonicalInteger(3);
Integer i4 = getCanonicalInteger(4);
Integer i5 = getCanonicalInteger(5);
Integer i6 = getCanonicalInteger(6);
Integer i7 = getCanonicalInteger(7);
//Loop through getting canonical integers until there is not
//enough space, and the garbage collector reclaims some.
for (int i = 0; i < REPEAT; i++)
ic = getCanonicalInteger(i);
//Now just re-access the first 10 integers (0 to 9) and
//the 0, 1, 2, 8, and 9 integers will need to be reset in
//the access method since they will have been reclaimed
for (int i = 0; i < 10; i++)
ic = getCanonicalInteger(i);
System.out.println(ic);
}
catch(Exception e){e.printStackTrace();}
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