--- jsr166/src/main/java/util/ArrayList.java 2016/11/16 00:17:25 1.44 +++ jsr166/src/main/java/util/ArrayList.java 2017/05/06 06:49:45 1.50 @@ -91,7 +91,7 @@ import java.util.function.UnaryOperator; * should be used only to detect bugs. * *

This class is a member of the - * + * * Java Collections Framework. * * @param the type of elements in this list @@ -578,8 +578,9 @@ public class ArrayList extends Abstra */ public void clear() { modCount++; - Arrays.fill(elementData, 0, size, null); - size = 0; + final Object[] es = elementData; + for (int to = size, i = size = 0; i < to; i++) + es[i] = null; } /** @@ -669,13 +670,17 @@ public class ArrayList extends Abstra outOfBoundsMsg(fromIndex, toIndex)); } modCount++; - final Object[] es = elementData; - final int oldSize = size; - System.arraycopy(es, toIndex, es, fromIndex, oldSize - toIndex); - Arrays.fill(es, size -= (toIndex - fromIndex), oldSize, null); + shiftTailOverGap(elementData, fromIndex, toIndex); // checkInvariants(); } + /** Erases the gap from lo to hi, by sliding down following elements. */ + private void shiftTailOverGap(Object[] es, int lo, int hi) { + System.arraycopy(es, hi, es, lo, size - hi); + for (int to = size, i = (size -= hi - lo); i < to; i++) + es[i] = null; + } + /** * A version of rangeCheck used by add and addAll. */ @@ -761,10 +766,8 @@ public class ArrayList extends Abstra w += end - r; throw ex; } finally { - final int oldSize = size, deleted = end - w; - modCount += deleted; - System.arraycopy(es, end, es, w, oldSize - end); - Arrays.fill(es, size -= deleted, oldSize, null); + modCount += end - w; + shiftTailOverGap(es, w, end); } } // checkInvariants(); @@ -772,15 +775,17 @@ public class ArrayList extends Abstra } /** - * Save the state of the {@code ArrayList} instance to a stream (that - * is, serialize it). + * Saves the state of the {@code ArrayList} instance to a stream + * (that is, serializes it). * + * @param s the stream + * @throws java.io.IOException if an I/O error occurs * @serialData The length of the array backing the {@code ArrayList} * instance is emitted (int), followed by all of its elements * (each an {@code Object}) in the proper order. */ private void writeObject(java.io.ObjectOutputStream s) - throws java.io.IOException{ + throws java.io.IOException { // Write out element count, and any hidden stuff int expectedModCount = modCount; s.defaultWriteObject(); @@ -799,8 +804,12 @@ public class ArrayList extends Abstra } /** - * Reconstitute the {@code ArrayList} instance from a stream (that is, - * deserialize it). + * Reconstitutes the {@code ArrayList} instance from a stream (that is, + * deserializes it). + * @param s the stream + * @throws ClassNotFoundException if the class of a serialized object + * could not be found + * @throws java.io.IOException if an I/O error occurs */ private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException { @@ -1291,9 +1300,8 @@ public class ArrayList extends Abstra public Spliterator spliterator() { checkForComodification(); - // ArrayListSpliterator is not used because late-binding logic - // is different here - return new Spliterator<>() { + // ArrayListSpliterator not used here due to late-binding + return new Spliterator() { private int index = offset; // current index, modified on advance/split private int fence = -1; // -1 until used; then one past last index private int expectedModCount; // initialized when fence set @@ -1307,12 +1315,11 @@ public class ArrayList extends Abstra return hi; } - public ArrayListSpliterator trySplit() { + public ArrayList.ArrayListSpliterator trySplit() { int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; - // ArrayListSpliterator could be used here as the source is already bound + // ArrayListSpliterator can be used here as the source is already bound return (lo >= mid) ? null : // divide range in half unless too small - new ArrayListSpliterator<>(root, lo, index = mid, - expectedModCount); + root.new ArrayListSpliterator(lo, index = mid, expectedModCount); } public boolean tryAdvance(Consumer action) { @@ -1354,7 +1361,7 @@ public class ArrayList extends Abstra } public long estimateSize() { - return (long) (getFence() - index); + return getFence() - index; } public int characteristics() { @@ -1364,6 +1371,9 @@ public class ArrayList extends Abstra } } + /** + * @throws NullPointerException {@inheritDoc} + */ @Override public void forEach(Consumer action) { Objects.requireNonNull(action); @@ -1391,11 +1401,11 @@ public class ArrayList extends Abstra */ @Override public Spliterator spliterator() { - return new ArrayListSpliterator<>(this, 0, -1, 0); + return new ArrayListSpliterator(0, -1, 0); } /** Index-based split-by-two, lazily initialized Spliterator */ - static final class ArrayListSpliterator implements Spliterator { + final class ArrayListSpliterator implements Spliterator { /* * If ArrayLists were immutable, or structurally immutable (no @@ -1429,15 +1439,12 @@ public class ArrayList extends Abstra * these streamlinings. */ - private final ArrayList list; private int index; // current index, modified on advance/split private int fence; // -1 until used; then one past last index private int expectedModCount; // initialized when fence set - /** Create new spliterator covering the given range */ - ArrayListSpliterator(ArrayList list, int origin, int fence, - int expectedModCount) { - this.list = list; // OK if null unless traversed + /** Creates new spliterator covering the given range. */ + ArrayListSpliterator(int origin, int fence, int expectedModCount) { this.index = origin; this.fence = fence; this.expectedModCount = expectedModCount; @@ -1445,23 +1452,17 @@ public class ArrayList extends Abstra private int getFence() { // initialize fence to size on first use int hi; // (a specialized variant appears in method forEach) - ArrayList lst; if ((hi = fence) < 0) { - if ((lst = list) == null) - hi = fence = 0; - else { - expectedModCount = lst.modCount; - hi = fence = lst.size; - } + expectedModCount = modCount; + hi = fence = size; } return hi; } - public ArrayListSpliterator trySplit() { + public ArrayListSpliterator trySplit() { int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; return (lo >= mid) ? null : // divide range in half unless too small - new ArrayListSpliterator<>(list, lo, index = mid, - expectedModCount); + new ArrayListSpliterator(lo, index = mid, expectedModCount); } public boolean tryAdvance(Consumer action) { @@ -1470,9 +1471,9 @@ public class ArrayList extends Abstra int hi = getFence(), i = index; if (i < hi) { index = i + 1; - @SuppressWarnings("unchecked") E e = (E)list.elementData[i]; + @SuppressWarnings("unchecked") E e = (E)elementData[i]; action.accept(e); - if (list.modCount != expectedModCount) + if (modCount != expectedModCount) throw new ConcurrentModificationException(); return true; } @@ -1481,13 +1482,13 @@ public class ArrayList extends Abstra public void forEachRemaining(Consumer action) { int i, hi, mc; // hoist accesses and checks from loop - ArrayList lst; Object[] a; + Object[] a; if (action == null) throw new NullPointerException(); - if ((lst = list) != null && (a = lst.elementData) != null) { + if ((a = elementData) != null) { if ((hi = fence) < 0) { - mc = lst.modCount; - hi = lst.size; + mc = modCount; + hi = size; } else mc = expectedModCount; @@ -1496,7 +1497,7 @@ public class ArrayList extends Abstra @SuppressWarnings("unchecked") E e = (E) a[i]; action.accept(e); } - if (lst.modCount == mc) + if (modCount == mc) return; } } @@ -1504,7 +1505,7 @@ public class ArrayList extends Abstra } public long estimateSize() { - return (long) (getFence() - index); + return getFence() - index; } public int characteristics() { @@ -1524,6 +1525,9 @@ public class ArrayList extends Abstra return (bits[i >> 6] & (1L << i)) == 0; } + /** + * @throws NullPointerException {@inheritDoc} + */ @Override public boolean removeIf(Predicate filter) { return removeIf(filter, 0, size); @@ -1558,9 +1562,7 @@ public class ArrayList extends Abstra for (i = beg; i < end; i++) if (isClear(deathRow, i - beg)) es[w++] = es[i]; - final int oldSize = size; - System.arraycopy(es, end, es, w, oldSize - end); - Arrays.fill(es, size -= (end - w), oldSize, null); + shiftTailOverGap(es, w, end); // checkInvariants(); return true; } else {