Implement a queue using an array - Java

I'm trying to implement a queue ADT using an array for a homework assignment (were it up to me I would be using a linked list, but I guess the professor wants us to learn new things or something XD). Anyway, I'm working on a method to add an element to the end of the queue, this same method should create a new re-sized array if it gets out of bounds, and this is the method I'm struggling with (the enqueue() method). Here is my code:

import java.util.Arrays;


public class Queue<T> implements QueueInterface<T> {

    private T[] a;
    private int sz;

    public Queue(int capacity) {
        sz = 0;
        @SuppressWarnings("unchecked")
        T[] tempQueue = (T[])new Object[capacity];
        a= tempQueue;
    }

    public void enqueue(T newEntry) {
        try {
        for (int i=0; i<a.length; i++) {
                if (a[i] == null) {
                    a[i] = newEntry;
                    break;
                }
            }
        sz++;
        }
        catch (ArrayIndexOutOfBoundsException e) {
            @SuppressWarnings("unchecked")
            T[] tempQueue = (T[])new Object[a.length*+5];
            a= tempQueue;
            for (int i=0; i<a.length; i++) {
                if (a[i] == null) {
                    a[i] = newEntry;
                    break;
                }

            }
        }
    }

    public T dequeue() {
        T result = a[0];
        a[0] = null;
        for (int i=1; i<a.length;i++) {
            a[i-1] = a[i];
        }
        sz--;
        return result;
    }

    public T getFront() {
        return a[0];
    }

    public boolean isEmpty() {
        for (int i=0; i<a.length; i++) {
            if (a[i] != null) {
                return false;
            }
        }
        return true;
    }

    public void clear() {
        for (int i=0; i<a.length; i++) {
            a[i] = null;
            sz--;
        }
    }

    @Override
    public String toString() {
        return "Queue [a=" + Arrays.toString(a) + ", sz=" + sz + "]";
    }

}

Thanks so much for your time everyone!!!