Java的数组，栈，队列

import java.util.Arrays;

public class Array<E> {

    private E[] data;

    private int size;

    //构造函数，传入数组的容量capacity构造Array
    public Array(int capacity) {
        this.data = (E[]) new Object[capacity];
        size = 0;
    }

    //无参数构造函数
    public Array() {
        this(10);
    }

    //获取数组的个数
    public int getSize() {
        return size;
    }

    //获取数组的容量
    public int getCapacity() {
        return data.length;
    }

    //数组是否为空
    public boolean isEmpty() {
        return size == 0;
    }

    //添加最后一个元素
    public void addLast(E e) {
        add(size,e);
    }

    //添加第一个元素
    public void addFirst(E e){
        add(0,e);
    }

    //获取inde索引位置的元素
    public E get(int index){
        if (index < 0 || index >= size){
            throw new IllegalArgumentException("Get failed,index is illegal");
        }
        return data[index];
    }

    public void set(int index,E e){
        if (index < 0 || index >= size){
            throw new IllegalArgumentException("Get failed,index is illegal");
        }
        data[index] =  e;
    }

    //添加元素
    public void add(int index,E e){
        if (index > size || index < 0){
            throw new IllegalArgumentException("add failed beceause index > size or index < 0,Array is full.");
        }
        if (size == data.length){
            resize(data.length * 2);
        }
        for (int i = size - 1; i >= index; i--) {
            data[i+1] = data[i];
        }
        data[index] = e;
        size ++;

    }

    //扩容数组
    private void resize(int newCapacity) {
        E[] newData = (E[]) new Object[newCapacity];
        for (int i = 0; i < size; i++) {
            newData[i] = data[i];
        }
        data = newData;
    }

    public E[] getData() {
        return data;
    }

    //查找数组中是否有元素e
    public boolean contains(E e){
        for (int i = 0; i < size; i++) {
            if (data[i].equals(e)){
                return true;
            }
        }
        return false;
    }

    //根据元素查看索引
    public int find(E e){
        for (int i = 0; i < size; i++) {
            if (data[i].equals(e)){
                return i;
            }
        }
        return -1;
    }

    //删除某个索引元素
    public E remove(int index){
        if(index < 0 || index >= size){
            throw new IllegalArgumentException("detele is fail,index < 0 or index >= size");
        }
        E ret = data[index];
        for (int i = index + 1; i < size; i++) {
            data[i - 1] = data[i];
        }
        size --;
        data[size] = null;
        if (size < data.length / 2){
            resize(data.length / 2);
        }
        return  ret;
    }

    //删除首个元素
    public E removeFirst(){
        return this.remove(0);
    }

    //删除最后一个元素
    public E removeLast(){
        return this.remove(size - 1);
    }

    //从数组删除元素e
    public void removeElemen(E e){
        int index = find(e);
        if (index != -1){
            remove(index);
        }

    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder("");
        sb.append(String.format("Array:size = %d,capacity = %d 
",size,data.length));
        sb.append("[");
        for (int i = 0; i < size; i++) {
            sb.append(data[i]);
            if (i != size - 1){
                sb.append(",");
            }
        }
        sb.append("]");
        return sb.toString();
    }
}

 队列

public class ArrayStack<E> implements Stack<E> {


    Array<E> array;

    public ArrayStack(int capacity) {
        array = new Array<>(capacity);
    }

    public ArrayStack() {
        this.array = new Array<>();
    }

    @Override
    public int getSize() {
        return array.getSize();
    }

    @Override
    public boolean isEmpty() {
        return array.isEmpty();
    }

    @Override
    public void push(E e) {
        array.addLast(e);
    }

    @Override
    public E pop() {
        return array.removeLast();
    }

    @Override
    public E peek() {
        return array.getLast();
    }

    public int getCapacity(){
        return array.getCapacity();
    }



    @Override
    public String toString() {
        StringBuilder res = new StringBuilder("");
        res.append("Stack:");
        res.append("[");
        for (int i = 0; i < array.getSize(); i++) {
            res.append(array.get(i));
            if ( i != array.getSize() - 1){
                res.append(",");
            }
        }
        res.append("] top");
        return res.toString();
    }
}

队列

public class ArrayQueue<E> implements Queue<E> {

    Array<E> array;

    public ArrayQueue(int capacity) {
        this.array = new Array<>(capacity);
    }

    public ArrayQueue() {
        this.array = new Array<>();
    }

    @Override
    public int getSize() {
        return array.getSize();
    }

    @Override
    public boolean isEmpty() {
        return array.isEmpty();
    }

    @Override
    public void enqueue(E e) {
        array.addLast(e);
    }

    @Override
    public E dequeue() {
        return array.removeFirst();
    }

    @Override
    public E getFront() {
        return array.getFirst();
    }

    public int getCapacity(){
        return array.getCapacity();
    }

    @Override
    public String toString() {
        StringBuilder res = new StringBuilder("");
        res.append("Queue [");
        for (int i = 0; i < array.getSize(); i++) {
            res.append(array.get(i));
            if (i != array.getSize() - 1){
                res.append(",");
            }
        }
        res.append("] tail");
        return res.toString();
    }
    public static void main(String[] args){
        ArrayQueue<Integer> arrayQueue = new ArrayQueue<>();
        for (int i = 0; i < 10; i++) {
            arrayQueue.enqueue(i);
            System.out.println(arrayQueue);
            if (i % 3 == 2){
                arrayQueue.dequeue();
                System.out.println(arrayQueue);
            }
        }
    }
}

第二种队列算法

public class LoopQueue<E> implements Queue<E>
{

    private E[] data;

    private int front, tail;

    private int size;

    public LoopQueue(int capacity)
    {
        data = (E[]) new Object[capacity + 1];
    }

    public LoopQueue()
    {
        this(10);
    }

    @Override
    public int getSize()
    {
        return size;
    }

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

    public int getCapacity()
    {
        return data.length - 1;
    }

    //入队
    @Override
    public void enqueue(E e)
    {
        if (front == (tail + 1) % data.length)
        {
            resize(getCapacity() * 2);
        }
        data[tail] = e;
        tail = (tail + 1) % data.length;
        size++;
    }

    private void resize(int newCapacity)
    {
        E[] newData = (E[]) new Object[newCapacity + 1];
        for (int i = 0; i < size; i++)
        {
            newData[i] = data[(i + 1) % data.length];
        }
        data = newData;
        front = 0;
        tail = size;

    }

    //出队
    @Override
    public E dequeue() throws Exception
    {
        if (isEmpty())
        {
            throw new Exception("LoopQueue is isEmpty,dequeue is fail.");
        }
        E ret = data[front];
        front = (front + 1) % data.length;
        size--;
        if (getCapacity() / 4 == size && getCapacity() / 2 != 0)
        {
            resize(getCapacity() / 2);
        }
        return ret;
    }

    @Override
    public E getFront() throws Exception
    {
        return data[front];
    }

    @Override
    public String toString()
    {
        StringBuilder res = new StringBuilder("");
        res.append(String.format("LoopQueue:size = %d,getCapacity = %d 
",size,getCapacity()));
        res.append("LoopQueue frot[");
        for (int i = front;i != tail;i = (i + 1) % data.length)
        {
            res.append(data[i]);
            if (tail != (i + 1) % data.length )
            {
                res.append(",");
            }
        }
        res.append("] tail");
        return res.toString();
    }
    public static void main(String[] args) throws Exception
    {
        LoopQueue<Integer> loopQueue = new LoopQueue<Integer>();
        for (int i = 0; i < 10; i++)
        {
            loopQueue.enqueue(i);
            if (i % 3 == 2)
            {
                loopQueue.dequeue();
            }
            System.out.println(loopQueue);
        }
    }
}