CSCI152 L7 P1

//////////////////////////////////////////////////////////////////////// IntQueue ADT (interface)
public interface IntQueue {

    /**
     * Adds an element to the end of the queue.
     *
     * @param value element to be added to the end of the queue
     */
    public void enqueue(int value);

    /**
     * Removes and returns the front most element of the queue
     *
     * @return the front most element of the queue
     * @throws Exception if the queue is empty
     */
    public int dequeue() throws Exception;

    /**
     * @return the size of the queue
     */
    public int getSize();

    /**
     * Removes all elements from the queue
     */
    public void clear();

    /**
     * @return a String representation of the queue
     */
    @Override
    public String toString();
}

/////////////////////////////////////////////////////////////////////////// ArrayIntQueue Implementation
public class ArrayIntQueue implements IntQueue{

    private int[] values;
    private int size;
    private int front;
    private int back;

    public ArrayIntQueue(){
        values=new int[10];
        size=0;
        front=0;
        back=9;
    }

    @Override
    public void enqueue(int value) {
        if (size==values.length){
            int i=front, j=0;
            int[] tmp=new int[2*values.length];
            do {
                tmp[j++]=values[i++];
                i%=values.length;
            } while (i!=front);
            values=tmp;
            front=0;
            back=j-1;
        }
        back=(++back)%values.length;
        values[back]=value;
        size++;
    }

    @Override
    public int dequeue() throws Exception {
        if (size==0){
            throw new Exception("The queue is empty.");
        }
        int result=values[front++];
        front%=values.length;
        size--;
        return result;
    }

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

    @Override
    public void clear() {
        values=new int[10];
        size=0;
        front=0;
        back=9;
    }

    @Override
    public String toString(){
        String res="front[";
        int i=front, j=0, c=0;
        while (c<size) {
            res+=values[i++];
            i%=values.length;
            if (c<size-1){
                res+=", ";
            }
            c++;
        }
        res+="]back";
        return res;
    }
}

///////////////////////////////////////////////////////////////////////////// TestClass
public class testClass {
    public static void main(String[] args){

        IntQueue myQueue=new ArrayIntQueue();

        try {
            System.out.println(myQueue.dequeue());
        } catch (Exception ex){
            System.out.println(ex.getMessage());
        }

        for (int i=0; i<8; i++){
            myQueue.enqueue(i+1);
        }
        System.out.println(myQueue);
        System.out.println("Size: "+myQueue.getSize()+"\n");

        try {
            myQueue.dequeue();
            myQueue.dequeue();
            myQueue.dequeue();
        } catch (Exception ex){
            System.out.println(ex.getMessage());
        }
        System.out.println(myQueue);
        System.out.println("Size: "+myQueue.getSize()+"\n");

        for (int i=0; i<9; i++){
            myQueue.enqueue(i+1);
            myQueue.enqueue(i+1);
            try {
                myQueue.dequeue();
                myQueue.dequeue();
            } catch (Exception ex){
                System.out.println(ex.getMessage());
            }
            System.out.println(" iteration #"+(i+1));
            System.out.println(myQueue);
            System.out.println("Size: "+myQueue.getSize());
        }
        System.out.println();

        myQueue.clear();
        System.out.println(myQueue);
        System.out.println("Size: "+myQueue.getSize()+"\n");

        for (int i=0; i<22; i++){
            myQueue.enqueue(i+1);
        }
        System.out.println(myQueue);
        System.out.println("Size: "+myQueue.getSize()+"\n");
    }
}