선형 표
우선,우 리 는 먼저 가장 간단 한 순서 표를 배운다.
첫 번 째 단 계 는 순서 표 의 기본 정의 와 조작 을 제시 합 니 다.
package net.itaem.list;
/**
* ，
*
*
* ： {a1,a2,a3...an}， ：DataType。
* ， ； ， ；
*
* @author qq:846705189
* */
public interface List<T> {
/**
*
* @param index
* @param element
* */
public void add(int index, T element);
/**
* ，
* @param index
* @return
* */
public T remove(int index);
/**
*
* @return
* */
public int size();
/**
*
* */
public void clear();
}
제2 부 실현 순서 표 의 인터페이스
package net.itaem.list.impl;
import net.itaem.list.List;
/**
* List， java.util.ArrayList
* List，
*
* @author luohong
* */
public class ArrayList<T> implements List<T> {
//
private int size;
//
private int length;
// ， ， ， Object，
Object[] elements;
/**
* ， 10
* */
public ArrayList(){
this.length = 10;
elements = new Object[10];
}
/**
* ，
* */
public ArrayList(int length){
if(length < 0) throw new RuntimeException(" 0");
if(length > Integer.MAX_VALUE) throw new RuntimeException(" ");
this.length = length;
elements = new Object[length];
}
@Override
public void add(int index, T element) {
//
checkIndex(index);
// ，
if(size == length) return;
// ，
if(index == size)
elements[size] = element;
else{
// index length index+1 length+1，
for(int i=size-1; i>=index; i--) elements[i+1] = elements[i];
elements[index] = element;
}
// ， 1
size++;
}
@SuppressWarnings("unchecked")
@Override
public T remove(int index) {
//
checkIndex(index);
//
T result = null;
// ，
if(index == size-1) {
result = (T)elements[index];
elements[index] = null;
}else{
// ， index+1 size-1 index size-2
result = (T)elements[index];
for(int i=index+1; i<size; i++) {
elements[i-1] = elements[i];
}
// null，
elements[size-1] = null;
}
// ， -1
size--;
return result;
}
@Override
public int size() {
return size;
}
public int length(){
return length;
}
@Override
public void clear() {
// null
for(int i=0; i<length; i++){
if(elements[i] != null) elements[i] = null;
}
//
size = 0;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
for(Object element: elements){
sb.append(element + ", ");
}
// “,”
String elementStr = sb.substring(0, sb.length()-2);
return "the ArrayList length is " + length + " and the elements of size is " + size + "; elements is " + elementStr;
}
// ，
private void checkIndex(int index) {
if(index < 0 || index >= length) throw new RuntimeException(" " + index + " ， ");
}
public static void main(String[] args){
//
List<Integer> testList = new ArrayList<Integer>(10);
for(int i=0; i<10; i++){
testList.add(i, i);
}
System.out.println("before remove
" + testList);
System.out.println("remove element is " + testList.remove(8));
System.out.println("after remove
" + testList);
System.out.println("add List in index 5 with value 555");
testList.add(5, 555);
System.out.println("after add
" + testList);
System.out.println("before clear list size " + testList.size());
testList.clear();
System.out.println("after clear list size " + testList.size());
System.out.println(testList);
}
}
다음은 출력 결과 입 니 다.
before remove
the ArrayList length is 10 and the elements of size is 10; elements is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
remove element is 8
after remove
the ArrayList length is 10 and the elements of size is 9; elements is 0, 1, 2, 3, 4, 5, 6, 7, 9, null
add List in index 5 with value 555
after add
the ArrayList length is 10 and the elements of size is 10; elements is 0, 1, 2, 3, 4, 555, 5, 6, 7, 9
before clear list size 10
after clear list size 0
the ArrayList length is 10 and the elements of size is 0; elements is null, null, null, null, null, null, null, null, null, null위 에서 사용 하 는 것 은 배열 이 실현 하 는 선형 표 입 니 다.아래 는 체인 식 저장 구 조 를 이용 하여 선형 표를 실현 합 니 다.자바 util.LinkedList 와 유사 합 니 다.여러분 이 관심 이 있 으 면 소스 코드 를 읽 을 수 있 습 니 다.
운행 결과
package net.itaem.list.impl;
import net.itaem.list.List;
/**
* 。
* ： ， ， 。
* ， 。
* */
public class LinkedList<T> implements List<T>{
// ， ， ，
private class Node<E>{
//
private E data;
//
private Node<E> next;
/**
*
* */
public Node(E data, Node<E> next){
this.data = data;
this.next = next;
}
/**
*
* */
public Node(){}
public Node<E> next(){
return next;
}
public void setNext(Node<E> next){
this.next = next;
}
public E data(){
return data;
}
}
//
private Node<T> head;
//
private int size;
/**
*
* ，
* */
public LinkedList(){
head = new Node<T>();
}
@Override
public void add(int index, T element) {
checkIndex(index);
if(head == null && index > 0) throw new RuntimeException(" null， " + index + " ");
size++;
Node<T> p = head;
//
if(index == size){
Node<T> newEle = new Node<T>(element, null);
p.setNext(newEle);
return;
}else{
//
for(int i=0; i<index; i++){
p = p.next();
}
// ，
Node<T> newEle = new Node<T>(element, p.next());
p.setNext(newEle);
}
}
private void checkIndex(int index) {
if(index < 0) throw new RuntimeException(" " + index + " ");
if(index > size()) throw new RuntimeException(" " + size());
}
@Override
public T remove(int index) {
checkIndex(index);
size--;
T data = null;
Node<T> p = head;
if(p != null && p.next() != null){
for(int i=0; i<index; i++){
p = p.next();
}
data = p.next().data();
p.setNext(p.next().next());
}
return data;
}
@Override
public int size() {
return size;
}
@Override
public void clear() {
head = null;
size = 0;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
Node<T> p = head;
if(head != null){
if(p != null && p.next() != null){
while(p.next() != null){
p = p.next();
sb.append(p.data() + " ");
}
}
}else{
sb.append("null");
}
return "the linked list size is " + size + " and the elements is " + sb.toString();
}
public static void main(String[] args) {
LinkedList<Integer> linkedList = new LinkedList<Integer>();
//
for(int i=0; i<10; i++){
linkedList.add(i, i);
}
System.out.println("before add
" + linkedList);
linkedList.add(2, 22);
System.out.println("affter add
" + linkedList);
// remove
// ：remove ，
System.out.println("before remove
" + linkedList);
System.out.println("remove index 5 and value is " + linkedList.remove(5));
System.out.println("after remove
" + linkedList);
//
linkedList.clear();
System.out.println("after clear " + linkedList.toString());
}
}
총결산
선형 표 는 사실 생활 에서 매우 보편적 이 고 가장 보편적 인 데이터 구조 이다.위의 코드 를 통 해 알 수 있 듯 이 배열 을 통 해 모 의 한 선형 표 는 컴퓨터 의 실현 내부,즉 물리 적 논리 이자 데이터 논리 와 같은 방식 으로 이 루어 진다.물리 적 실현 과정 은 컴퓨터 메모리 가 서로 인접 한 저장 공간 을 개척 한 다음 에 요소 의 선후 순서에 따라 질서 있 게 저장 하 는 것 과 같다.그래서 이런 방식 으로 이 루어 진 순서 표 는 요소 에서 찾 는 것 이 빠 르 고 효율 적 이다.왜냐하면 컴퓨터 는 첫 번 째 요소 와 마지막 요 소 를 찾 든 똑 같이 효율 적 이기 때문이다.
체인 시 계 는 사실 생활 속 에서 도 매우 보편적이다.체인 테이블 의 실현 방식 은 메모리 사용 을 제어 하 는 과정 에서 더욱 우세 하 다.프로그램 은 동적 으로 저장 공간 을 분배 하기 때문이다.삽입 삭제 도 효율 적 이다.왜 더 효율 적 인가요?만약 에 삽입 위치 가 다 르 면 똑 같이 O(n)의 알고리즘 효율 입 니 다.그러나 같은 곳 에 데 이 터 를 삽입 할 때 프로그램 이 이 위 치 를 처음 찾 은 것 은 O(n)이 고 그 다음 에 노드 를 삽입 하 는 것 은 O(1)입 니 다.순서 선형 표 는 삽입 할 때마다 O(n)...
java.util.Array List 와 LinkedList 를 비교 합 니 다.
before add
the linked list size is 10 and the elements is 0 1 2 3 4 5 6 7 8 9
affter add
the linked list size is 11 and the elements is 0 1 22 2 3 4 5 6 7 8 9
before remove
the linked list size is 11 and the elements is 0 1 22 2 3 4 5 6 7 8 9
remove index 5 and value is 4
after remove
the linked list size is 10 and the elements is 0 1 22 2 3 5 6 7 8 9
after clear the linked list size is 0 and the elements is null빨간색 코드 부분 에서 자바 util.Array List 가 get(int index)에 있 을 때 명령 을 실행 하 는 것 만 볼 수 있 습 니 다.삽입,삭제 시 이동 요 소 를 모 를 필요 가 있 습 니 다.
/*
* %W% %E%
*
* Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.util;
/**
* Resizable-array implementation of the <tt>List</tt> interface. Implements
* all optional list operations, and permits all elements, including
* <tt>null</tt>. In addition to implementing the <tt>List</tt> interface,
* this class provides methods to manipulate the size of the array that is
* used internally to store the list. (This class is roughly equivalent to
* <tt>Vector</tt>, except that it is unsynchronized.)<p>
*
* The <tt>size</tt>, <tt>isEmpty</tt>, <tt>get</tt>, <tt>set</tt>,
* <tt>iterator</tt>, and <tt>listIterator</tt> operations run in constant
* time. The <tt>add</tt> operation runs in <i>amortized constant time</i>,
* that is, adding n elements requires O(n) time. All of the other operations
* run in linear time (roughly speaking). The constant factor is low compared
* to that for the <tt>LinkedList</tt> implementation.<p>
*
* Each <tt>ArrayList</tt> instance has a <i>capacity</i>. The capacity is
* the size of the array used to store the elements in the list. It is always
* at least as large as the list size. As elements are added to an ArrayList,
* its capacity grows automatically. The details of the growth policy are not
* specified beyond the fact that adding an element has constant amortized
* time cost.<p>
*
* An application can increase the capacity of an <tt>ArrayList</tt> instance
* before adding a large number of elements using the <tt>ensureCapacity</tt>
* operation. This may reduce the amount of incremental reallocation.
*
* <p><strong>Note that this implementation is not synchronized.</strong>
* If multiple threads access an <tt>ArrayList</tt> instance concurrently,
* and at least one of the threads modifies the list structurally, it
* <i>must</i> be synchronized externally. (A structural modification is
* any operation that adds or deletes one or more elements, or explicitly
* resizes the backing array; merely setting the value of an element is not
* a structural modification.) This is typically accomplished by
* synchronizing on some object that naturally encapsulates the list.
*
* If no such object exists, the list should be "wrapped" using the
* {@link Collections#synchronizedList Collections.synchronizedList}
* method. This is best done at creation time, to prevent accidental
* unsynchronized access to the list:<pre>
* List list = Collections.synchronizedList(new ArrayList(...));</pre>
*
* <p>The iterators returned by this class's <tt>iterator</tt> and
* <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is
* structurally modified at any time after the iterator is created, in any way
* except through the iterator's own <tt>remove</tt> or <tt>add</tt> methods,
* the iterator will throw a {@link ConcurrentModificationException}. Thus, in
* the face of concurrent modification, the iterator fails quickly and cleanly,
* rather than risking arbitrary, non-deterministic behavior at an undetermined
* time in the future.<p>
*
* Note that the fail-fast behavior of an iterator cannot be guaranteed
* as it is, generally speaking, impossible to make any hard guarantees in the
* presence of unsynchronized concurrent modification. Fail-fast iterators
* throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
* Therefore, it would be wrong to write a program that depended on this
* exception for its correctness: <i>the fail-fast behavior of iterators
* should be used only to detect bugs.</i><p>
*
* This class is a member of the
* <a href="{@docRoot}/../technotes/guides/collections/index.html">
* Java Collections Framework</a>.
*
* @author Josh Bloch
* @author Neal Gafter
* @version %I%, %G%
* @see Collection
* @see List
* @see LinkedList
* @see Vector
* @since 1.2
*/
public class ArrayList<E> extends AbstractList<E>
implements List<E>, RandomAccess, Cloneable, java.io.Serializable
{
private static final long serialVersionUID = 8683452581122892189L;
/**
* The array buffer into which the elements of the ArrayList are stored.
* The capacity of the ArrayList is the length of this array buffer.
*/
private transient Object[] elementData;
/**
* The size of the ArrayList (the number of elements it contains).
*
* @serial
*/
private int size;
/**
* Constructs an empty list with the specified initial capacity.
*
* @param initialCapacity the initial capacity of the list
* @exception IllegalArgumentException if the specified initial capacity
* is negative
*/
public ArrayList(int initialCapacity) {
super();
if (initialCapacity < 0)
throw new IllegalArgumentException("Illegal Capacity: "+
initialCapacity);
this.elementData = new Object[initialCapacity];
}
/**
* Constructs an empty list with an initial capacity of ten.
*/
public ArrayList() {
this(10);
}
/**
* Constructs a list containing the elements of the specified
* collection, in the order they are returned by the collection's
* iterator.
*
* @param c the collection whose elements are to be placed into this list
* @throws NullPointerException if the specified collection is null
*/
public ArrayList(Collection<? extends E> c) {
elementData = c.toArray();
size = elementData.length;
// c.toArray might (incorrectly) not return Object[] (see 6260652)
if (elementData.getClass() != Object[].class)
elementData = Arrays.copyOf(elementData, size, Object[].class);
}
/**
* Trims the capacity of this <tt>ArrayList</tt> instance to be the
* list's current size. An application can use this operation to minimize
* the storage of an <tt>ArrayList</tt> instance.
*/
public void trimToSize() {
modCount++;
int oldCapacity = elementData.length;
if (size < oldCapacity) {
elementData = Arrays.copyOf(elementData, size);
}
}
/**
* Increases the capacity of this <tt>ArrayList</tt> instance, if
* necessary, to ensure that it can hold at least the number of elements
* specified by the minimum capacity argument.
*
* @param minCapacity the desired minimum capacity
*/
public void ensureCapacity(int minCapacity) {
modCount++;
int oldCapacity = elementData.length;
if (minCapacity > oldCapacity) {
Object oldData[] = elementData;
int newCapacity = (oldCapacity * 3)/2 + 1;
if (newCapacity < minCapacity)
newCapacity = minCapacity;
// minCapacity is usually close to size, so this is a win:
elementData = Arrays.copyOf(elementData, newCapacity);
}
}
/**
* Returns the number of elements in this list.
*
* @return the number of elements in this list
*/
public int size() {
return size;
}
/**
* Returns <tt>true</tt> if this list contains no elements.
*
* @return <tt>true</tt> if this list contains no elements
*/
public boolean isEmpty() {
return size == 0;
}
/**
* Returns <tt>true</tt> if this list contains the specified element.
* More formally, returns <tt>true</tt> if and only if this list contains
* at least one element <tt>e</tt> such that
* <tt>(o==null ? e==null : o.equals(e))</tt>.
*
* @param o element whose presence in this list is to be tested
* @return <tt>true</tt> if this list contains the specified element
*/
public boolean contains(Object o) {
return indexOf(o) >= 0;
}
/**
* Returns the index of the first occurrence of the specified element
* in this list, or -1 if this list does not contain the element.
* More formally, returns the lowest index <tt>i</tt> such that
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
* or -1 if there is no such index.
*/
public int indexOf(Object o) {
if (o == null) {
for (int i = 0; i < size; i++)
if (elementData[i]==null)
return i;
} else {
for (int i = 0; i < size; i++)
if (o.equals(elementData[i]))
return i;
}
return -1;
}
/**
* Returns the index of the last occurrence of the specified element
* in this list, or -1 if this list does not contain the element.
* More formally, returns the highest index <tt>i</tt> such that
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
* or -1 if there is no such index.
*/
public int lastIndexOf(Object o) {
if (o == null) {
for (int i = size-1; i >= 0; i--)
if (elementData[i]==null)
return i;
} else {
for (int i = size-1; i >= 0; i--)
if (o.equals(elementData[i]))
return i;
}
return -1;
}
/**
* Returns a shallow copy of this <tt>ArrayList</tt> instance. (The
* elements themselves are not copied.)
*
* @return a clone of this <tt>ArrayList</tt> instance
*/
public Object clone() {
try {
ArrayList<E> v = (ArrayList<E>) super.clone();
v.elementData = Arrays.copyOf(elementData, size);
v.modCount = 0;
return v;
} catch (CloneNotSupportedException e) {
// this shouldn't happen, since we are Cloneable
throw new InternalError();
}
}
/**
* Returns an array containing all of the elements in this list
* in proper sequence (from first to last element).
*
* <p>The returned array will be "safe" in that no references to it are
* maintained by this list. (In other words, this method must allocate
* a new array). The caller is thus free to modify the returned array.
*
* <p>This method acts as bridge between array-based and collection-based
* APIs.
*
* @return an array containing all of the elements in this list in
* proper sequence
*/
public Object[] toArray() {
return Arrays.copyOf(elementData, size);
}
/**
* Returns an array containing all of the elements in this list in proper
* sequence (from first to last element); the runtime type of the returned
* array is that of the specified array. If the list fits in the
* specified array, it is returned therein. Otherwise, a new array is
* allocated with the runtime type of the specified array and the size of
* this list.
*
* <p>If the list fits in the specified array with room to spare
* (i.e., the array has more elements than the list), the element in
* the array immediately following the end of the collection is set to
* <tt>null</tt>. (This is useful in determining the length of the
* list <i>only</i> if the caller knows that the list does not contain
* any null elements.)
*
* @param a the array into which the elements of the list are to
* be stored, if it is big enough; otherwise, a new array of the
* same runtime type is allocated for this purpose.
* @return an array containing the elements of the list
* @throws ArrayStoreException if the runtime type of the specified array
* is not a supertype of the runtime type of every element in
* this list
* @throws NullPointerException if the specified array is null
*/
public <T> T[] toArray(T[] a) {
if (a.length < size)
// Make a new array of a's runtime type, but my contents:
return (T[]) Arrays.copyOf(elementData, size, a.getClass());
System.arraycopy(elementData, 0, a, 0, size);
if (a.length > size)
a[size] = null;
return a;
}
// Positional Access Operations
/**
* Returns the element at the specified position in this list.
*
* @param index index of the element to return
* @return the element at the specified position in this list
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E get(int index) {
RangeCheck(index);
return (E) elementData[index];
}
/**
* Replaces the element at the specified position in this list with
* the specified element.
*
* @param index index of the element to replace
* @param element element to be stored at the specified position
* @return the element previously at the specified position
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E set(int index, E element) {
RangeCheck(index);
E oldValue = (E) elementData[index];
elementData[index] = element;
return oldValue;
}
/**
* Appends the specified element to the end of this list.
*
* @param e element to be appended to this list
* @return <tt>true</tt> (as specified by {@link Collection#add})
*/
public boolean add(E e) {
ensureCapacity(size + 1); // Increments modCount!!
elementData[size++] = e;
return true;
}
/**
* Inserts the specified element at the specified position in this
* list. Shifts the element currently at that position (if any) and
* any subsequent elements to the right (adds one to their indices).
*
* @param index index at which the specified element is to be inserted
* @param element element to be inserted
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public void add(int index, E element) {
if (index > size || index < 0)
throw new IndexOutOfBoundsException(
"Index: "+index+", Size: "+size);
ensureCapacity(size+1); // Increments modCount!!
System.arraycopy(elementData, index, elementData, index + 1,
size - index);
elementData[index] = element;
size++;
}
/**
* Removes the element at the specified position in this list.
* Shifts any subsequent elements to the left (subtracts one from their
* indices).
*
* @param index the index of the element to be removed
* @return the element that was removed from the list
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E remove(int index) {
RangeCheck(index);
modCount++;
E oldValue = (E) elementData[index];
int numMoved = size - index - 1;
if (numMoved > 0)
System.arraycopy(elementData, index+1, elementData, index,
numMoved);
elementData[--size] = null; // Let gc do its work
return oldValue;
}
/**
* Removes the first occurrence of the specified element from this list,
* if it is present. If the list does not contain the element, it is
* unchanged. More formally, removes the element with the lowest index
* <tt>i</tt> such that
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>
* (if such an element exists). Returns <tt>true</tt> if this list
* contained the specified element (or equivalently, if this list
* changed as a result of the call).
*
* @param o element to be removed from this list, if present
* @return <tt>true</tt> if this list contained the specified element
*/
public boolean remove(Object o) {
if (o == null) {
for (int index = 0; index < size; index++)
if (elementData[index] == null) {
fastRemove(index);
return true;
}
} else {
for (int index = 0; index < size; index++)
if (o.equals(elementData[index])) {
fastRemove(index);
return true;
}
}
return false;
}
/*
* Private remove method that skips bounds checking and does not
* return the value removed.
*/
private void fastRemove(int index) {
modCount++;
int numMoved = size - index - 1;
if (numMoved > 0)
System.arraycopy(elementData, index+1, elementData, index,
numMoved);
elementData[--size] = null; // Let gc do its work
}
/**
* Removes all of the elements from this list. The list will
* be empty after this call returns.
*/
public void clear() {
modCount++;
// Let gc do its work
for (int i = 0; i < size; i++)
elementData[i] = null;
size = 0;
}
/**
* Appends all of the elements in the specified collection to the end of
* 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. (This implies that the behavior of this call is
* undefined if the specified collection is this list, and this
* list is nonempty.)
*
* @param c collection containing elements to be added to this list
* @return <tt>true</tt> if this list changed as a result of the call
* @throws NullPointerException if the specified collection is null
*/
public boolean addAll(Collection<? extends E> c) {
Object[] a = c.toArray();
int numNew = a.length;
ensureCapacity(size + numNew); // Increments modCount
System.arraycopy(a, 0, elementData, size, numNew);
size += numNew;
return numNew != 0;
}
/**
* Inserts all of the elements in the specified collection into this
* list, starting at the specified position. 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 the list in the order that they are returned by the
* specified collection's iterator.
*
* @param index index at which to insert the first element from the
* specified collection
* @param c collection containing elements to be added to this list
* @return <tt>true</tt> if this list changed as a result of the call
* @throws IndexOutOfBoundsException {@inheritDoc}
* @throws NullPointerException if the specified collection is null
*/
public boolean addAll(int index, Collection<? extends E> c) {
if (index > size || index < 0)
throw new IndexOutOfBoundsException(
"Index: " + index + ", Size: " + size);
Object[] a = c.toArray();
int numNew = a.length;
ensureCapacity(size + numNew); // Increments modCount
int numMoved = size - index;
if (numMoved > 0)
System.arraycopy(elementData, index, elementData, index + numNew,
numMoved);
System.arraycopy(a, 0, elementData, index, numNew);
size += numNew;
return numNew != 0;
}
/**
* Removes from this list all of the elements whose index is between
* <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive.
* Shifts any succeeding elements to the left (reduces their index).
* This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements.
* (If <tt>toIndex==fromIndex</tt>, this operation has no effect.)
*
* @param fromIndex index of first element to be removed
* @param toIndex index after last element to be removed
* @throws IndexOutOfBoundsException if fromIndex or toIndex out of
* range (fromIndex < 0 || fromIndex >= size() || toIndex
* > size() || toIndex < fromIndex)
*/
protected void removeRange(int fromIndex, int toIndex) {
modCount++;
int numMoved = size - toIndex;
System.arraycopy(elementData, toIndex, elementData, fromIndex,
numMoved);
// Let gc do its work
int newSize = size - (toIndex-fromIndex);
while (size != newSize)
elementData[--size] = null;
}
/**
* Checks if the given index is in range. If not, throws an appropriate
* runtime exception. This method does *not* check if the index is
* negative: It is always used immediately prior to an array access,
* which throws an ArrayIndexOutOfBoundsException if index is negative.
*/
private void RangeCheck(int index) {
if (index >= size)
throw new IndexOutOfBoundsException(
"Index: "+index+", Size: "+size);
}
/**
* Save the state of the <tt>ArrayList</tt> instance to a stream (that
* is, serialize it).
*
* @serialData The length of the array backing the <tt>ArrayList</tt>
* instance is emitted (int), followed by all of its elements
* (each an <tt>Object</tt>) in the proper order.
*/
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException{
// Write out element count, and any hidden stuff
int expectedModCount = modCount;
s.defaultWriteObject();
// Write out array length
s.writeInt(elementData.length);
// Write out all elements in the proper order.
for (int i=0; i<size; i++)
s.writeObject(elementData[i]);
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
}
/**
* Reconstitute the <tt>ArrayList</tt> instance from a stream (that is,
* deserialize it).
*/
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
// Read in size, and any hidden stuff
s.defaultReadObject();
// Read in array length and allocate array
int arrayLength = s.readInt();
Object[] a = elementData = new Object[arrayLength];
// Read in all elements in the proper order.
for (int i=0; i<size; i++)
a[i] = s.readObject();
}
}
빨간색 부분 코드 를 통 해 알 수 있 듯 이 이 클래스 는 내부 클래스 를 정의 하여 노드 를 모 의 한다.java.util.LinkedList 는 요 소 를 찾 을 때 비교적 비효 율 적 이지 만 삽입,삭제 할 때 효율 적 입 니 다.
java.util.Array List 와 java.util.LinkedList 사용 총화
프로그램 이 집합 에 있 는 요 소 를 자주 얻 으 려 면 Array List 를 사용 할 수 있 습 니 다.예 를 들 어 학생 이 로그 인 하려 면 데이터 베이스 에서 모든 데 이 터 를 찾 은 다음 에 하나의 집합 에 넣 은 다음 에 집합 중의 요 소 를 자주 읽 어야 한다.
프로그램 이 자주 집합 에 있 는 요 소 를 삽입 하고 삭제 해 야 한다 면 링크 드 리스트 를 사용 할 수 있다.예 를 들 어 카 트 는 사용자 의 화물 을 집합 에 넣 거나 집합 에서 삭제 해 야 한다.
주의 점
범 형의 기술 을 채 택 했 지만 클래스 안 은 수 조 를 통 해 이 루어 졌 다.하하,범 형 에 대해 서 는 잠시 토론 하지 않 겠 습 니 다.여러분 은 위의 코드 를 먼저 이해 하면 됩 니 다.
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