EVALUATION

The deeper problem of returning the same object on each call to next()
is being addressed via 6312706.  Most of the obvious manifestations
of that behavior are being fixed here.
                                     

EVALUATION

Doug Lea suggested changing ArrayList(Collection) constructor to
make it slightly more robust in the sense that the code would work 
if the argument was any other collection class
having the same bug as IdentityHashMap.  
(Collection classes often get copied and modified)
                                     

SUGGESTED FIX

--- /u/martin/ws/mustang/src/share/classes/java/util/IdentityHashMap.java	2004-08-27 15:54:50.658979000 -0700
+++ /u/martin/ws/toArray/src/share/classes/java/util/IdentityHashMap.java	2005-08-07 22:56:46.405135000 -0700
@@ -1109,13 +1109,26 @@
         }
 
         public Object[] toArray() {
-            List<Map.Entry<K,V>> c = new ArrayList<Map.Entry<K,V>>(size());
-            for (Map.Entry<K,V> e : this)
-                c.add(new AbstractMap.SimpleEntry<K,V>(e));
-            return c.toArray();
+	    int size = size();
+	    Object[] result = new Object[size];
+	    Iterator<Map.Entry<K,V>> it = iterator();
+	    for (int i=0; i < size; i++)
+		result[i] = new AbstractMap.SimpleEntry<K,V>(it.next());
+	    return result;
         }
         public <T> T[] toArray(T[] a) {
-	    return (T[])toArray(); // !!!!
+	    int size = size();
+	    if (a.length < size)
+		a = (T[])java.lang.reflect.Array
+		    .newInstance(a.getClass().getComponentType(), size);
+
+	    Iterator<Map.Entry<K,V>> it = iterator();
+	    Object[] result = a;
+	    for (int i=0; i<size; i++)
+		result[i] = new AbstractMap.SimpleEntry<K,V>(it.next());
+	    if (a.length > size)
+		a[size] = null;
+	    return a;
         }
     }
 
--- /u/martin/ws/mustang/test/java/util/IdentityHashMap/ToArray.java	2004-08-27 16:19:49.069257000 -0700
+++ /u/martin/ws/toArray/test/java/util/IdentityHashMap/ToArray.java	2005-08-07 22:56:46.955474000 -0700
@@ -1,16 +1,19 @@
 /*
- * @test    1.1 01/08/06
- * @bug     4485486
- * @summary IdentityHashMap's lack of internal entry objects caused the 
- *          inherited (AbstractMap) version of toArray to return garbage
- *          when called on the entrySet view.
- * @author  Josh Bloch
+ * @test    1.2 05/08/07
+ * @bug     4485486 6197726
+ * @summary IdentityHashMap's entrySet toArray tests
+ * @author  Josh Bloch, Martin Buchholz
  */
 
 import java.util.*;
 
 public class ToArray {
     public static void main(String[] args) {
+	//----------------------------------------------------------------
+	// IdentityHashMap's lack of internal entry objects caused
+	// the inherited (AbstractMap) version of toArray to
+	// return garbage when called on the entrySet view.
+	//----------------------------------------------------------------
         Map m = new IdentityHashMap();
         m.put("french", "connection");
         m.put("polish", "sausage");
@@ -20,5 +23,28 @@
 
         mArray[0].toString();
         mArray[1].toString();
+
+	//----------------------------------------------------------------
+	// IdentityHashMap.entrySet().toArray(T[] a) used to simply
+	// return toArray() !
+	//----------------------------------------------------------------
+	IdentityHashMap<Integer,Integer> map
+	    = new IdentityHashMap<Integer,Integer>();
+	Set<Map.Entry<Integer,Integer>> es = map.entrySet();
+	if (es.toArray().length != 0)
+	    throw new Error("non-empty");
+	if (es.toArray(new Object[]{Boolean.TRUE})[0] != null)
+	    throw new Error("non-null");
+	map.put(7,49);
+	if (es.toArray().length != 1)
+	    throw new Error("length");
+	Object[] x = es.toArray(new Object[]{Boolean.TRUE, Boolean.TRUE});
+	if (x[1] != null)
+	    throw new Error("non-null");
+	Map.Entry e = (Map.Entry) x[0];
+	if (! e.getKey().equals(new Integer(7)))
+	    throw new Error("bad key");
+	if (! e.getValue().equals(new Integer(49)))
+	    throw new Error("bad value");
     }
 }
--- /u/martin/ws/mustang/src/share/classes/java/util/ArrayList.java	2005-06-08 14:05:18.407383000 -0700
+++ /u/martin/ws/toArray/src/share/classes/java/util/ArrayList.java	2005-08-14 18:17:17.878695000 -0700
@@ -132,9 +132,8 @@
     public ArrayList(Collection<? extends E> c) {
         size = c.size();
         // Allow 10% room for growth
-        elementData = (E[])new Object[
-                      (int)Math.min((size*110L)/100,Integer.MAX_VALUE)]; 
-        c.toArray(elementData);
+	int capacity = (int) Math.min((size*110L)/100, Integer.MAX_VALUE);
+        elementData = (E[]) c.toArray(new Object[capacity]);
     }
 
     /**
                                     

EVALUATION

I independently found this while examining 

5031890 (coll spec) Collection toArray() does not specify empty collection behavior

I have a nice test framework for testing this kind of stuff more globally,
and have been working on toArray before, so I'm taking ownership of this bug.
                                     

EVALUATION

toArray() could indeed be more efficient and, more importantly,
toArray(T[]) is not completely implemented.

###@###.### 2005-06-15 18:25:51 GMT