1009 tut 2

package circArray;

import java.util.NoSuchElementException;

public class CircularArrayQueue implements MyQueue {

    private int[] circularArray;
    private int noElements;
    private int head;
    private int tail;

    public CircularArrayQueue(){
        circularArray = new int[10];
        noElements = 0;
        head = 0;
        tail = 0;
    }

    @Override
    public void enqueue(int in) {
        int n = circularArray.length;
        if(noElements == n){
            increaseArrayCap();
        }
        circularArray[tail] = in;
        noElements++;
        tail++;
        if(tail == n && noElements <= n){
            tail = 0;
        }
    }

    @Override
    public int dequeue() throws NoSuchElementException {
        int n = circularArray.length;
        int removed = circularArray[head];
        noElements --;
        head++;
        if(head == n && noElements <= n){
            head = 0;
        }
        return removed;
    }

    @Override
    public int noItems() {
        return noElements;
    }

    @Override
    public boolean isEmpty() {
        if(noElements == 0){
            return true;
        }
        else{
        return false;
        }
    }

    public int getCapacity(){
        int capacity = circularArray.length - noElements;
        return capacity;
    }

    private void increaseArrayCap(){
        int n = circularArray.length;
        int[] biggerArray = new int[2*n];
        for(int i = 0; i < n; i++){
            biggerArray[i] = circularArray[i];
        }
        circularArray = biggerArray;
    }
}