public class Queue {
private Double[] elements;
private int back;
private static final int FRONT = 0;
public static final int DEFAULT_CAPACITY = 10;
/** Construct a queue with an ad hoc capacity */
/** Construct a queue with the default capacity */
/** put a new object at the end of the queue;
* follow the model of StackOfIntegers to expand the capacity
* if the queue is full
*/
int initCapacity;

public Queue()
{
    initCapacity = DEFAULT_CAPACITY;
    elements = new Double [initCapacity];
}

public Queue(int newValue){
    initCapacity = newValue;
    elements = new Double [initCapacity];
}


public void enqueue(Double value) {
    if (back == initCapacity){
        initCapacity = initCapacity * 2;
        Double [] elements2 = new Double [initCapacity];
        for (int i =0; i < elements.length; i++){
            elements2[i] = elements[i];
        }
        elements = elements2;
    }
    elements[back]= value;
    back+=1;

}
/** Return and remove the front element from the queue ;
* this method must call the private method shift()
*/
public Double dequeue() {
    Double temp = elements[FRONT] ;
    shift();
    back = back - 1;
// we have to temporarily store the current front of the line
    return temp;

}
/** Return the element at the front of the queue for inspection */
public Double peek() {
    return elements[FRONT];
}
/** Test whether the queue is empty */
public boolean isEmpty() {
    return back == FRONT;
}
/** Return the number of elements in the queue */
public int getSize() {
    return back;
}
/** shift everything one position to the front and null out the
old back of the line */
private void shift() {
for ( int i = 1; i < back; i++ )
elements[i-1] = elements[i] ;
elements[--back] = null ;
}
/** A rough-and-ready way to see what is going on in our queue */
public void dump() {
System.out.print( "Elements: " ) ;
for ( int i = 0; i < elements.length; i++ )
System.out.print( elements[i] + " " ) ;
System.out.println() ;
System.out.println( "Back: " + back ) ;
}
}

public class TestQueueOfDoubles {
public static void main(String[] args){
    Queue Object = new Queue( 12);
    Queue DefaultObject = new Queue();
    Queue Object2 = new Queue( 14);
    Queue Object3 = new Queue( 9);
    System.out.println(Object.initCapacity);
    System.out.println(DefaultObject.initCapacity);
    System.out.println(Object2.initCapacity);
    System.out.println(Object3.initCapacity);
}