CircularArrayQueue

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package cz.cvut.fel.pr1;

/**
 *
 * @author
 */
public class CircularArrayQueue implements Queue {

    String[] array;
    int headIndex = 0;
    int lowIndex = 0;

    public CircularArrayQueue() {
        array = new String[5];

    }

    public CircularArrayQueue(int capacity) {
        array = new String[capacity];

    }

    /**
     * It will count number of elements in CircularArrayQueue, not a size of the
     * structure
     *
     * @return the number of elements in CircularArrayQueue (int)
     */
    public int size() {
        int size;
        size = headIndex-lowIndex;
        return size;
    }

    /**
     * It will check if CircularArrayQueue is empty
     *
     * @return <code>true</code> if the CircularArrayQueue is empty and contains
     * no elements <code>false</code> otherwise (CircularArrayQueue contains
     * atleast one element).
     */
    public boolean isEmpty() {
        if (size() == 0) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * It will check if CircularArrayQueue is full
     *
     * @return <code>true</code> if the CircularArrayQueue is full
     * <code>false</code> otherwise.
     */
    public boolean isFull() {
        if (size() == array.length) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * This method will enqueue the String to CircularArrayQueue
     *
     * @param obj the String object that we want add to CircularArrayQueue
     * @return <code>true</code> if the obj param is added to CircularArrayQueue
     * <code>false</code> otherwise (if CircularArrayQueue is full or if we obj
     * param is null).
     */
    public boolean enqueue(String obj) {
        if (isFull() == true || obj == null) {
            return false;
        } else {
            array[headIndex] = obj;
            headIndex++;
            return true;
        }
    }

    /**
     * This method will dequeue the first String from CircularArrayQueue
     *
     * @return <code>String value</code> if the CircularArrayQueue is not empty
     * <code>null</code> otherwise (if CircularArrayQueue is empty).
     */
    public String dequeue() {
        if (isEmpty() == true){
            return null;
        } else {
            String halp = array[lowIndex];
            array[lowIndex] = null;
            return halp;
        }
    }

    /**
     * It will print all elements from CircularArrayQueue
     */
    public void printAllElements() {
        for (int i = lowIndex; i <= headIndex; i++){
            System.out.println(array[i]);
        }
    }
}