package com.bootdo.common.config.collection.test.collectionmap.arraylist;
/**
* @ClassName : MyArrayList
* @Description: 模仿实现底层的ArrayList的一些方法的实现
* @Author: 13394
* @CreateDate: 2018/10/19 22:46
* @Version: 1.0
*/
public class MyArrayList {
private static final Object[] EMPTY_ELEMENTDATA = {};
private Object[] elementData;
private int size;
public MyArrayList() {
this(10); //初始化调用一个构造方法
}
public MyArrayList(int initialCapacity) {
if (initialCapacity > 0) {
this.elementData = new Object[initialCapacity];
} else if (initialCapacity == 0) {
this.elementData = EMPTY_ELEMENTDATA;
} else {
throw new IllegalArgumentException("Illegal Capacity: " +
initialCapacity);
}
}
public boolean add(Object obj) {
ensureCapacityInternal();//数组的扩容
elementData[size++] = obj;
return true;
}
private void rangeCheckForAdd(int index) {
if (index > size || index < 0) {
throw new IndexOutOfBoundsException();
}
}
private String outOfBoundsMsg(int index) {
return "index:" + index + "size:" + size;
}
private void ensureCapacityInternal() {
if (size == elementData.length) {
Object[] newArray = new Object[size * 2 + 1];
System.arraycopy(elementData, 0, newArray, 0, elementData.length);
elementData = newArray;
}
}
public void add(int index, Object obj) {
rangeCheckForAdd(index); //判断数组是否越界
ensureCapacityInternal(); //数组的扩容
System.arraycopy(elementData, index, elementData, index + 1, size - index);
elementData[index] = obj;
size++;
}
public boolean isEmpty() {
return size == 0;
}
public Object get(int index) {
rangeCheck(index);
return elementData[index];
}
private void rangeCheck(int index) {
if (index >= size)
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
public static void main(String[] args) {
MyArrayList myArrayList = new MyArrayList();
myArrayList.add("ads");
myArrayList.add(1, "13132");
//System.out.println(myArrayList.get(4));
System.out.println(myArrayList.get(1));
}
}
LinkList
package com.bootdo.common.config.collection.test.collectionmap.linkedlist;
import java.util.LinkedList;
import java.util.Map;
/**
* @ClassName : MyLinkList
* @Description: TODO
* @Author: 13394
* @CreateDate: 2018/10/20 19:08
* @Version: 1.0
*/
public class MyLinkList {
private Node first;
private Node last;
private int size;
public void add(Object obj) {
Node node = new Node();
if (first == null) {
node.setPrevious(null);
node.setObj(obj);
node.setNext(null);
first = node;
last = node;
} else {
node.setPrevious(last);
node.setObj(obj);
node.setNext(null);
last = node;
}
size++;
}
public int size() {
return size;
}
private String outOfBoundsMsg(int index) {
return "index:" + index + " " + "size:" + size;
}
private void rangeCheck(int index) {
if (index > size) {
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
}
public Object get(int index) {
rangeCheck(index);
Node temp = null;
if (first != null) {
temp = first;
for (int i = 0; i < index; i++) {
temp = temp.next;
}
}
return temp.obj;
}
public Node node(int index){
Node temp = null;
if(first!=null){
if (index < (size >> 1)) {
temp = first;
for(int i=0;inext;
}
}else{
temp = last;
for (int i = size - 1; i > index; i--){
temp = temp.previous;
}
}
}
// LinkedList l;
return temp;
}
public void remove(int index){
Node temp = node(index);
if(temp!=null){
Node up = temp.previous;
Node down = temp.next;
up.next = down;
down.previous = up;
size--;
}
}
public void add(int index,Object obj){
Node temp = node(index);
Node newNode = new Node();
newNode.obj = obj;
if(temp!=null){
Node up = temp.previous;
up.next = newNode;
newNode.previous = up;
newNode.next = temp;
temp.previous = newNode;
size++;
}
}
public static void main(String[] args) {
MyLinkList myLinkList = new MyLinkList();
myLinkList.add("ada");
myLinkList.add("dasda");
System.out.println(myLinkList.size());
System.out.println(myLinkList.get(5));
}
}
package com.bootdo.common.config.collection.test.collectionmap.linkedlist;
/**
* @ClassName : Node
* @Description:
* @Author: 13394
* @CreateDate: 2018/10/20 19:14
* @Version: 1.0
*/
public class Node {
Node previous; //上一个节点
Object obj;
Node next; //下一个节点
public Node(){
}
public Node(Node previous, Object obj, Node next) {
this.previous = previous;
this.obj = obj;
this.next = next;
}
public Node getPrevious() {
return previous;
}
public void setPrevious(Node previous) {
this.previous = previous;
}
public Object getObj() {
return obj;
}
public void setObj(Object obj) {
this.obj = obj;
}
public Node getNext() {
return next;
}
public void setNext(Node next) {
this.next = next;
}
}
Map
package com.bootdo.common.config.collection.test.collectionmap.map;
import java.util.LinkedList;
/**
* @ClassName : MyMap002
* @Description: TODO
* @Author: 13394
* @CreateDate: 2018/10/21 18:49
* @Version: 1.0
*/
public class MyMap002 {
LinkedList[] arr = new LinkedList[9]; //Map的底层结构就是：数组+链表!
int size;
public void put(Object key,Object value){
Entry e = new Entry(key,value);
int hash = key.hashCode();
hash = hash<0?-hash:hash;
int a = hash%arr.length;
if(arr[a]==null){
LinkedList list = new LinkedList();
arr[a] = list;
list.add(e);
}else{
LinkedList list = arr[a];
for(int i=0;iif(e2.key.equals(key)){
e2.value = value; //键值重复直接覆盖！
return;
}
}
arr[a].add(e);
}
//a:1000-->1 b:10000-->13
}
public Object get(Object key){
int a = key.hashCode()%arr.length;
if(arr[a]!=null){
LinkedList list = arr[a];
for(int i=0;iif(e.key.equals(key)){
return e.value;
}
}
}
return null;
}
public static void main(String[] args) {
}
}