Queue

queue_IMyQueue.java

package week5.main.queue;

/**
 * Created by Agryzkov on 11.08.2016.
 */
public interface IMyQueue<E> {

    void insert(E element);

    E remove();

    E getFront();

    E getRear();

    int getSize();

    String toString();
}

queue_MyArrayQueue.java

package week5.main.queue;

/**
 * Created by Agryzkov on 11.08.2016.
 */
public class MyArrayQueue<E> implements IMyQueue<E> {

    private E[] arrayQueue;
    private final int DEFAULT_CAPACITY = 5;
    private int front, rear;


    public MyArrayQueue() { //Yanchevskaya A можно вызвать внутри конструктор public MyArrayQueue(int capacity)
        arrayQueue = (E[])(new Object[DEFAULT_CAPACITY]);
        front = rear = 0;
    }

    public MyArrayQueue(int capacity) {
        arrayQueue = (E[])(new Object[capacity]);
        front = rear = 0;
    }

    @Override
    public void insert(E element) {
        if (isFull()) {
            expansCapacity();
        }
        if (front != 0 && rear == arrayQueue.length - 1) {
            shiftElement();
        }
        arrayQueue[rear] = element;
        rear++;
    }

    @Override
    public E remove() {
        E result = null;
        if (isEmpty()) {
            System.out.println("queue is empty");
        } else {
            result = arrayQueue[front]; //Yanchevskaya A. Но сам элемент ты не обнуляешь?
            front ++;
        }
        return result;
    }

    @Override
    public E getFront() {
        return arrayQueue[front];
    }

    @Override
    public E getRear() {
        return arrayQueue[rear - 1]; //Yanchevskaya A. проверка на rear !=0
    }

    @Override
    public int getSize() {
        return rear - front;
    }

    @Override
    public String toString() {
        String str = ""; //Yanchevskaya A. используй StringBuilder
        for (int i = front; i < rear; i++){
            str+=String.valueOf(arrayQueue[i]) + "\t";
        }
        return str;
    }

    private boolean isEmpty() {
        return rear == front;
    }

    private boolean isFull() {
        return arrayQueue.length == getSize();
    }

    private void expansCapacity(){
        E[] largQueue = (E[])(new Object[getSize() * 2]);
        System.arraycopy(arrayQueue, 0, largQueue, 0, arrayQueue.length);
        arrayQueue = largQueue;
    }

    private void shiftElement() {
        E[] arrTemp = (E[])(new Object[arrayQueue.length]);
        System.arraycopy(arrayQueue, front, arrTemp, 0, arrayQueue.length);  //Yanchevskaya A. посл. параметр - это кол-во копируемых элементов, копируем size
        arrayQueue = arrTemp;
        rear = rear - front;
        front = 0;
    }
}

queue_MyLinkedQueue.java

package week5.main.queue;

import week5.main.stack.Node;

/**
 * Created by Agryzkov on 11.08.2016.
 */
public class MyLinkedQueue<E> implements IMyQueue<E> {

    private int capacity;
    private Node<E> front, rear;

    public MyLinkedQueue() {
        front = rear = null;
        capacity = 0;
    }

    public Boolean isEmpty() {
        return capacity == 0;
    }

    @Override
    public void insert(E element) {
        Node<E> node = new Node<E>(element);
        if (isEmpty()) {
            front = node; //Yanchevskaya A front = rear = node;
        } else {
            rear.setNext(node);
        }
        rear = node;
        capacity++;
    }

    @Override
    public E remove() {
        E result = null;
        if (isEmpty()) {
            System.out.println("stack is empty");
        } else {
            result = front.getValue(); //Yanchevskaya A если всего один элемент, то и хвост надо очищать
            front = front.getNext();
            capacity--;
        }
        return result;
    }

    @Override
    public E getFront() {
        E result = null;
        if (isEmpty()) {
            System.out.println("stack is empty");
        } else {
            result = front.getValue();
        }
        return result;
    }

    @Override
    public E getRear() {
        E result = null;
        if (isEmpty()) {
            System.out.println("stack is empty");
        } else {
            result = rear.getValue();
        }
        return result;
    }

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

    @Override
    public String toString(){
        String result = ""; //Yanchevskaya A use StringBuilder
        Node<E> current = front;

        while (current != null){
            result += String.valueOf(current.getValue()) + "\t";
            current = current.getNext();
        }
        return result;
    }
}