Java数据结构的实现

1.基于数组的链表

 package array;

 import java.util.Arrays;

 /**
  * 基于数组的链表
  *
  * @author 王彪
  *
  */
 public class MyArrayList {
     private static Object[] elements = null;
     private static int size = 0;
     private static final int DEFUAT_INITIAL_CAPACITY = 10;

     public MyArrayList() {
         this(10);
     }

     public MyArrayList(int initialCapacity) {
         if (initialCapacity < 0) {
             throw new IllegalArgumentException("输入容量有误");
         }
         elements = new Object[initialCapacity];
     }

 //初始化数组
     // 保存新元素
     public void add(Object ele) {
         // 数组的扩容问题
         if (size == elements.length) {
             Object[] temp = Arrays.copyOf(elements, elements.length * 2);
             elements = temp;
         }
         elements[size] = ele;
         size++;
     }

     public Object get(int index) {
         if (index < 0 || index >= size) {
             throw new IllegalArgumentException("输入索引有误");
         }
         return elements[index];
     }

     public void set(int index, Object newPlayerNum) {
         if (index < 0 || index >= size) {
             throw new IllegalArgumentException("输入索引有误");
         }
         elements[index] = newPlayerNum;
     }

     public void remove(int index) {
         if (index < 0 || index >= size) {
             throw new IllegalArgumentException("输入索引有误");
         }
         for (int i = index; i < size - 1; i++) {
             elements[i] = elements[i + 1];
         }
         elements[size - 1] = null;
         size--;
     }

     public String toString() {
         if (elements == null) {
             return null;
         }
         if (size == 0) {
             return "[]";
         }
         StringBuilder sb = new StringBuilder(size * 3 + 1);
         sb.append("[");
         for (int i = 0; i < size; i++) {
             sb.append(elements[i]);
             if (i < size - 1) {
                 sb.append(",");
             }
             if (i == size - 1) {
                 sb.append("]");
             }
         }
         return sb.toString();
     }

     public int size() {
         return size;
     }

     public boolean isEmpty() {
         return size == 0;
     }

     public void clear() {
         this.elements = new Object[DEFUAT_INITIAL_CAPACITY];
         size = 0;
     }

 }

---

2.双向链表

 package linked;

 public class MyLinkedArrayList {
     protected Node first;
     protected Node last;
     protected int size;

     public void addFirst(Object ele) {// 在头部增加
         Node node = new Node(ele);
         if (size == 0) {
             this.first = node;
             this.last = node;
         } else {
             node.next = this.first;
             this.first.prev = node;
             this.first = node;
         }
         size++;
     }

     public void addLast(Object ele) {// 在尾部增加
         Node node = new Node(ele);
         if (size == 0) {
             this.first = node;
             this.last = node;
         } else {
             this.last.next = node;
             node.prev = this.last;
             this.last = node;
         }
         size++;
     }

     public void remove(Object ele) {
         Node current = this.first;
         for (int i = 0; i < size; i++) {
             if (!current.ele.equals(ele)) {
                 if (current.next == null) {
                     return;
                 }
                 current = current.next;
             }
         }
         if (current == this.first) {
             this.first = current.next;
             this.first.prev = null;
         } else if (current == this.last) {
             this.last = current.prev;
             this.last.next = null;
         } else {
             current.prev.next = current.next;
             current.next.prev = current.prev;
         }
         size--;
     }

     @Override
     public String toString() {
         if (size == 0) {
             return "[]";
         } else {
             StringBuilder sb = new StringBuilder(size * 3 + 1);
             Node current = this.first;// 第一个节点
             sb.append("[");
             for (int i = 0; i < size; i++) {
                 sb.append(current.ele);
                 if (i != size - 1) {
                     sb.append(",");
                 } else {
                     sb.append("]");
                 }
                 current = current.next;
             }
             return sb.toString();
         }
     }

     public class Node {
         public Node(Object ele) {
             this.ele = ele;
         }

         Node prev;
         Node next;
         public Object ele;
     }
 }

---

3.双向队列

 package deque;

 import linked.MyLinkedArrayList;

 public class MyDeque extends MyLinkedArrayList {
     public Object getFirst() {
         return this.first.ele;
     }

     public Object getLast() {
         return this.last.ele;
     }

     public void removeFirst(Object ele) {
         super.remove(this.first);
     }

     public void removeLast(Object ele) {
         super.remove(this.last);
     }

     public void addFirst(Object ele) {
         super.addFirst(ele);
     }

     public void addLast(Object ele) {
         super.addLast(ele);
     }

 }

---

4.堆

 package stack;

 import array.MyArrayList;

 //栈
 public class MyStack extends MyArrayList {
     // 入栈
     public void push(Object ele) {
         super.add(ele);
     }

     // 删除栈顶元素
     public void pop() {
         int index = super.size() - 1;
         super.remove(index);
     }

     // 查询栈顶元素
     public Object peek() {
         int index = super.size() - 1;
         return super.get(index);
     }

 }