src/java.base/share/classes/java/util/AbstractSequentialList.java
changeset 47216 71c04702a3d5
parent 44743 f0bbd698c486
child 49433 b6671a111395
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/java/util/AbstractSequentialList.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,252 @@
+/*
+ * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.util;
+
+/**
+ * This class provides a skeletal implementation of the {@code List}
+ * interface to minimize the effort required to implement this interface
+ * backed by a "sequential access" data store (such as a linked list).  For
+ * random access data (such as an array), {@code AbstractList} should be used
+ * in preference to this class.<p>
+ *
+ * This class is the opposite of the {@code AbstractList} class in the sense
+ * that it implements the "random access" methods ({@code get(int index)},
+ * {@code set(int index, E element)}, {@code add(int index, E element)} and
+ * {@code remove(int index)}) on top of the list's list iterator, instead of
+ * the other way around.<p>
+ *
+ * To implement a list the programmer needs only to extend this class and
+ * provide implementations for the {@code listIterator} and {@code size}
+ * methods.  For an unmodifiable list, the programmer need only implement the
+ * list iterator's {@code hasNext}, {@code next}, {@code hasPrevious},
+ * {@code previous} and {@code index} methods.<p>
+ *
+ * For a modifiable list the programmer should additionally implement the list
+ * iterator's {@code set} method.  For a variable-size list the programmer
+ * should additionally implement the list iterator's {@code remove} and
+ * {@code add} methods.<p>
+ *
+ * The programmer should generally provide a void (no argument) and collection
+ * constructor, as per the recommendation in the {@code Collection} interface
+ * specification.<p>
+ *
+ * This class is a member of the
+ * <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
+ * Java Collections Framework</a>.
+ *
+ * @author  Josh Bloch
+ * @author  Neal Gafter
+ * @see Collection
+ * @see List
+ * @see AbstractList
+ * @see AbstractCollection
+ * @since 1.2
+ */
+
+public abstract class AbstractSequentialList<E> extends AbstractList<E> {
+    /**
+     * Sole constructor.  (For invocation by subclass constructors, typically
+     * implicit.)
+     */
+    protected AbstractSequentialList() {
+    }
+
+    /**
+     * Returns the element at the specified position in this list.
+     *
+     * <p>This implementation first gets a list iterator pointing to the
+     * indexed element (with {@code listIterator(index)}).  Then, it gets
+     * the element using {@code ListIterator.next} and returns it.
+     *
+     * @throws IndexOutOfBoundsException {@inheritDoc}
+     */
+    public E get(int index) {
+        try {
+            return listIterator(index).next();
+        } catch (NoSuchElementException exc) {
+            throw new IndexOutOfBoundsException("Index: "+index);
+        }
+    }
+
+    /**
+     * Replaces the element at the specified position in this list with the
+     * specified element (optional operation).
+     *
+     * <p>This implementation first gets a list iterator pointing to the
+     * indexed element (with {@code listIterator(index)}).  Then, it gets
+     * the current element using {@code ListIterator.next} and replaces it
+     * with {@code ListIterator.set}.
+     *
+     * <p>Note that this implementation will throw an
+     * {@code UnsupportedOperationException} if the list iterator does not
+     * implement the {@code set} operation.
+     *
+     * @throws UnsupportedOperationException {@inheritDoc}
+     * @throws ClassCastException            {@inheritDoc}
+     * @throws NullPointerException          {@inheritDoc}
+     * @throws IllegalArgumentException      {@inheritDoc}
+     * @throws IndexOutOfBoundsException     {@inheritDoc}
+     */
+    public E set(int index, E element) {
+        try {
+            ListIterator<E> e = listIterator(index);
+            E oldVal = e.next();
+            e.set(element);
+            return oldVal;
+        } catch (NoSuchElementException exc) {
+            throw new IndexOutOfBoundsException("Index: "+index);
+        }
+    }
+
+    /**
+     * Inserts the specified element at the specified position in this list
+     * (optional operation).  Shifts the element currently at that position
+     * (if any) and any subsequent elements to the right (adds one to their
+     * indices).
+     *
+     * <p>This implementation first gets a list iterator pointing to the
+     * indexed element (with {@code listIterator(index)}).  Then, it
+     * inserts the specified element with {@code ListIterator.add}.
+     *
+     * <p>Note that this implementation will throw an
+     * {@code UnsupportedOperationException} if the list iterator does not
+     * implement the {@code add} operation.
+     *
+     * @throws UnsupportedOperationException {@inheritDoc}
+     * @throws ClassCastException            {@inheritDoc}
+     * @throws NullPointerException          {@inheritDoc}
+     * @throws IllegalArgumentException      {@inheritDoc}
+     * @throws IndexOutOfBoundsException     {@inheritDoc}
+     */
+    public void add(int index, E element) {
+        try {
+            listIterator(index).add(element);
+        } catch (NoSuchElementException exc) {
+            throw new IndexOutOfBoundsException("Index: "+index);
+        }
+    }
+
+    /**
+     * Removes the element at the specified position in this list (optional
+     * operation).  Shifts any subsequent elements to the left (subtracts one
+     * from their indices).  Returns the element that was removed from the
+     * list.
+     *
+     * <p>This implementation first gets a list iterator pointing to the
+     * indexed element (with {@code listIterator(index)}).  Then, it removes
+     * the element with {@code ListIterator.remove}.
+     *
+     * <p>Note that this implementation will throw an
+     * {@code UnsupportedOperationException} if the list iterator does not
+     * implement the {@code remove} operation.
+     *
+     * @throws UnsupportedOperationException {@inheritDoc}
+     * @throws IndexOutOfBoundsException     {@inheritDoc}
+     */
+    public E remove(int index) {
+        try {
+            ListIterator<E> e = listIterator(index);
+            E outCast = e.next();
+            e.remove();
+            return outCast;
+        } catch (NoSuchElementException exc) {
+            throw new IndexOutOfBoundsException("Index: "+index);
+        }
+    }
+
+
+    // Bulk Operations
+
+    /**
+     * Inserts all of the elements in the specified collection into this
+     * list at the specified position (optional operation).  Shifts the
+     * element currently at that position (if any) and any subsequent
+     * elements to the right (increases their indices).  The new elements
+     * will appear in this list in the order that they are returned by the
+     * specified collection's iterator.  The behavior of this operation is
+     * undefined if the specified collection is modified while the
+     * operation is in progress.  (Note that this will occur if the specified
+     * collection is this list, and it's nonempty.)
+     *
+     * <p>This implementation gets an iterator over the specified collection and
+     * a list iterator over this list pointing to the indexed element (with
+     * {@code listIterator(index)}).  Then, it iterates over the specified
+     * collection, inserting the elements obtained from the iterator into this
+     * list, one at a time, using {@code ListIterator.add} followed by
+     * {@code ListIterator.next} (to skip over the added element).
+     *
+     * <p>Note that this implementation will throw an
+     * {@code UnsupportedOperationException} if the list iterator returned by
+     * the {@code listIterator} method does not implement the {@code add}
+     * operation.
+     *
+     * @throws UnsupportedOperationException {@inheritDoc}
+     * @throws ClassCastException            {@inheritDoc}
+     * @throws NullPointerException          {@inheritDoc}
+     * @throws IllegalArgumentException      {@inheritDoc}
+     * @throws IndexOutOfBoundsException     {@inheritDoc}
+     */
+    public boolean addAll(int index, Collection<? extends E> c) {
+        try {
+            boolean modified = false;
+            ListIterator<E> e1 = listIterator(index);
+            for (E e : c) {
+                e1.add(e);
+                modified = true;
+            }
+            return modified;
+        } catch (NoSuchElementException exc) {
+            throw new IndexOutOfBoundsException("Index: "+index);
+        }
+    }
+
+
+    // Iterators
+
+    /**
+     * Returns an iterator over the elements in this list (in proper
+     * sequence).<p>
+     *
+     * This implementation merely returns a list iterator over the list.
+     *
+     * @return an iterator over the elements in this list (in proper sequence)
+     */
+    public Iterator<E> iterator() {
+        return listIterator();
+    }
+
+    /**
+     * Returns a list iterator over the elements in this list (in proper
+     * sequence).
+     *
+     * @param  index index of first element to be returned from the list
+     *         iterator (by a call to the {@code next} method)
+     * @return a list iterator over the elements in this list (in proper
+     *         sequence)
+     * @throws IndexOutOfBoundsException {@inheritDoc}
+     */
+    public abstract ListIterator<E> listIterator(int index);
+}