数据结构队列的java实现，包括线性和链式两种方式

实现的思路为：

采用泛型的方式，首先定义了一个Queue的接口，然后通过实现该接口实现了线性和链式的两种形式的队列：

接口代码如下：

package com.peter.java.dsa.interfaces;

public interface Queue<T> {
    
    /* put item at rear of queue; */
    void insert(T data);

    /* take item from front of queue */
    T remove();

    /* peek at front of queue */
    T peek();

    boolean isEmpty();

    boolean isFull();

    int size();

    void clear();
}

线性栈的代码如下：

package com.peter.java.dsa.common;

import com.peter.java.dsa.interfaces.Queue;

public class LinearQueue<T> implements Queue<T> {
    private int capacity;
    private T[] t;
    private int front;
    private int rear;
    private int size;

    public LinearQueue() {
        // TODO Auto-generated constructor stub
        capacity = 16;
        t = (T[]) new Object[capacity];
        front = -1;
        rear = -1;
        size = 0;
    }

    public LinearQueue(int capacity) {
        this.capacity = capacity;
        t = (T[]) new Object[capacity];
        front = -1;
        rear = -1;
        size = 0;
    }

    @Override
    public void insert(T data) {
        // TODO Auto-generated method stub
        if (isEmpty()) {
            front = (front + 1) % t.length;
            t[front] = data;
            rear = (rear + 1) % t.length;
        } else {
            if (isFull()) {
                resize();
            }
            rear = (rear + 1) % t.length;
            t[rear] = data;
        }
        size++;
    }

    @Override
    public T remove() {
        // TODO Auto-generated method stub
        T tmp = null;
        if (!isEmpty()) {
            tmp = t[front];
            t[front] = null;
            front = (front + 1) % t.length;
            size--;
        }
        return tmp;
    }

    @Override
    public T peek() {
        // TODO Auto-generated method stub
        T tmp = null;
        if (!isEmpty()) {
            tmp = t[front];
        }
        return tmp;
    }

    @Override
    public boolean isEmpty() {
        // TODO Auto-generated method stub
        return front + rear == -2 && front == rear % t.length;
    }

    @Override
    public boolean isFull() {
        // TODO Auto-generated method stub
        return front == rear % t.length;
    }

    @Override
    public int size() {
        // TODO Auto-generated method stub
        return size;
    }

    @Override
    public String toString() {
        // TODO Auto-generated method stub
        StringBuffer buffer = new StringBuffer();
        buffer.append("Linear Queue Content:[");
        if (front < rear) {
            for (int i = front; i < rear + 1; i++) {
                buffer.append(t[i] + ",");
            }
        } else {
            for (int i = front; i < t.length; i++) {
                buffer.append(t[i] + ",");
            }
            for (int i = 0; i < rear + 1; i++) {
                buffer.append(t[i] + ",");
            }
        }
        buffer.append("]");
        buffer.replace(buffer.lastIndexOf(","), buffer.lastIndexOf(",") + 1, "");
        return buffer.toString();
    }

    private void resize() {
        int oldSize = t.length;
        T[] tmp = (T[]) new Object[oldSize * 2];
        for (int i = 0; i < oldSize; i++) {
            tmp[i] = t[front];
            front = (front + 1) % oldSize;
        }
        front = 0;
        rear = oldSize - 1;
    }

    @Override
    public void clear() {
        // TODO Auto-generated method stub
        front = -1;
        rear = -1;
    }

}

随着复习进度，后续代码会陆续更新。