can anyone please help me spot my errors?

[Anissa Pary]

Hello. I have 2 classes

import java.util.*;
import java.lang.reflect.Array;

public class CircularArrayQueue implements MyQueue {
	Integer[] circularArray;
	int front;
	int tail;
	int count;
	int capacity;

	public CircularArrayQueue() {
		circularArray = new Integer[7];
	}

	public void enqueue(int in) {
		if (getCapacity() == 0)
			resize();
		circularArray[tail] = in;
		count = count + 1;
		if (getCapacity() != 0) {
			if (tail == (circularArray.length - 1))
				tail = 0;
			else
				tail = tail + 1;
		}
	}

	@Override
	public int dequeue() throws NoSuchElementException {
		if (count != 0) {
			Integer removed;
			removed = circularArray[front];
			circularArray[front] = null;
			count = count - 1;
			while (true) {
				front = front + 1;
				if (isEmpty()) {
					front = 0;
					tail = 0;
					break;
				} else if (circularArray[front] != null) {
					break;
				}
			}
			return removed;
		} else {
			throw new NoSuchElementException();
		}
	}

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

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

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

	public void resize() {
		Integer[] newArray = new Integer[circularArray.length * 2];
		for (int i = 0; i < circularArray.length; i++) {
			newArray[i] = circularArray[i];
		}
		circularArray = newArray;
	}
}

import java.util.NoSuchElementException;

public interface MyQueue {
	void enqueue(int in);

	int dequeue() throws NoSuchElementException; // throw exception if isEmpty()
													// is true

	int noItems(); // returns the number of items in the array

	boolean isEmpty(); // true if queue is empty
}

and Test class

import java.util.*;
import junit.framework.TestCase;

public class CircularArrayQueueTest extends TestCase {

	private void checkSize(int length, MyQueue queue) {
		assertEquals("Queue has wrong number of elements", length,
				queue.noItems());
		if (length == 0)
			assertTrue("Queue should be empty", queue.isEmpty());
		else
			assertTrue("Queue should not be empty", !queue.isEmpty());
	}

	public void testSimple() {
		MyQueue queue = new CircularArrayQueue();
		checkSize(0, queue);
		queue.enqueue(3);
		checkSize(1, queue);
		try {
			assertEquals("Dequeue returns wrong element", 3, queue.dequeue());
		} catch (NoSuchElementException e) {
			throw e;
		}
		checkSize(0, queue);
	}

	public void testMultiInput() {
		MyQueue queue = new CircularArrayQueue();
		for (int i = 0; i < 7; ++i) {
			int r = (int) Math.round(Math.random());
			checkSize(0, queue);
			queue.enqueue(r);
			checkSize(1, queue);
			assertEquals("Dequeue returns wrong element", r, queue.dequeue());
		}

	}

	public void testManyEnqueueDequeue() {
		CircularArrayQueue queue = new CircularArrayQueue();
		int cnt = 0;
		for (int i = 0; i < 7; ++i) {
			if (Math.random() > 0.5) {
				queue.enqueue(i);
				cnt++;
			} else {
				if (!queue.isEmpty()) {
					queue.dequeue();
					cnt--;
				}
			}
			assertEquals("Correct number of items", cnt, queue.noItems());
		}
	}

	public void testLargeQueue() {
		MyQueue queue = new CircularArrayQueue();
		int[] r = new int[7];
		for (int i = 0; i < r.length; ++i) {
			r[i] = (int) Math.round(Math.random());
			checkSize(i, queue);
			queue.enqueue(r[i]);
		}
		for (int i = 0; i < r.length; ++i) {
			assertEquals("Dequeue returns wrong element", r[i], queue.dequeue());
			checkSize(r.length - i - 1, queue);
		}
		for (int i = 0; i < r.length; ++i) {
			r[i] = (int) Math.round(Math.random());
			checkSize(i, queue);
			queue.enqueue(r[i]);
		}
		for (int i = 0; i < r.length; ++i) {
			assertEquals("Dequeue returns wrong element", r[i], queue.dequeue());
			checkSize(r.length - i - 1, queue);
		}
	}

	public void testThrows() {
		MyQueue queue = new CircularArrayQueue();
		int[] r = new int[7];
		for (int i = 0; i < r.length; ++i) {
			r[i] = (int) Math.round(Math.random());
			checkSize(i, queue);
			queue.enqueue(r[i]);
		}
		for (int i = 0; i < r.length; ++i) {
			assertEquals("Dequeue returns wrong element", r[i], queue.dequeue());
			checkSize(r.length - i - 1, queue);
		}
		boolean throwsCorrectly = false;
		try {
			queue.dequeue();
		} catch (NoSuchElementException e) {
			throwsCorrectly = true;
		}
		assertTrue("Throws when dequeuing empty queue", throwsCorrectly);
	}

	public void testResize() {
		CircularArrayQueue queue = new CircularArrayQueue();
		assertTrue("Initial capacity too large", queue.getCapacity() <= 1024);
		for (int i = 0; i < 7; ++i) {
			queue.enqueue(i);
		}
		int currentCapacity = queue.getCapacity();
		while (currentCapacity > 0) {
			queue.enqueue(9);
			currentCapacity--;
			assertEquals("Array size should not change", currentCapacity,
					queue.getCapacity());
		}
		assertTrue("Should have reached capacity", queue.getCapacity() == 0);
		queue.enqueue(42);
		assertTrue("Should have resized array",
				currentCapacity < queue.getCapacity());
		currentCapacity = queue.getCapacity();
		for (int i = 0; i < 100; ++i) {
			queue.enqueue(i);
			currentCapacity--;
			assertEquals("Resizing too often (inefficient)", currentCapacity,
					queue.getCapacity());
		}
	}
}

1 failure at resizing It says resizing too often is inefficient and resizing was done 13 times. But I don't see why. Can anyone please help!

[Jeff Verdegan]

Anissa Pary wrote:
I am getting 6 errors and when I am debugging it is NullPointer in lines 136 and 140 and 137. But I don't see why. Can anyone please help!

That looks like 3 errors, not 6. And the code you posted doesn't have those line numbers.

[Scott Kimberly]

Jeff Verdegan wrote:

Anissa Pary wrote:
I am getting 6 errors and when I am debugging it is NullPointer in lines 136 and 140 and 137. But I don't see why. Can anyone please help!

That looks like 3 errors, not 6. And the code you posted doesn't have those line numbers.

Assuming thats all the code for the program, there are 214 lines. The errors are at like 48 or (line 48 i think is really line 136) of that last large block.

I find that null pointer exceptions come from variables that can be set to null be shouldnt be for the purposes of your code.

[Anissa Pary]

Sorry I have made a mistake and printed wrong stuff this six mistakes was from another program and here it is just a failure...

[Jeff Verdegan]

Anissa Pary wrote:Sorry I have made a mistake and printed wrong stuff this six mistakes was from another program and here it is just a failure...

Okay, so, what exact errors are you getting here and on which exact lines are they occurring?

[Anissa Pary]

Jeff Verdegan wrote:

Anissa Pary wrote:Sorry I have made a mistake and printed wrong stuff this six mistakes was from another program and here it is just a failure...

Okay, so, what exact errors are you getting here and on which exact lines are they occurring?

it is saying runs:6/6 errors:0 failures: 1
junit.framework.AssertionFailedError: Resizing too often (inefficient) expected: <-1> but was <13> at CircularArrayQueueTest.testResize(CircularArrayQueueTest.java:122). So, it means

assertEquals("Resizing too often (inefficient)", currentCapacity,queue.getCapacity());

in the method:

public void testResize() {
		CircularArrayQueue queue = new CircularArrayQueue();
		assertTrue("Initial capacity too large", queue.getCapacity() <= 1024);
		for (int i = 0; i < 7; ++i) {
			queue.enqueue(i);
		}
		int currentCapacity = queue.getCapacity();
		while (currentCapacity > 0) {
			queue.enqueue(9);
			currentCapacity--;
			assertEquals("Array size should not change", currentCapacity,
					queue.getCapacity());
		}
		assertTrue("Should have reached capacity", queue.getCapacity() == 0);
		queue.enqueue(42);
		assertTrue("Should have resized array",
				currentCapacity < queue.getCapacity());
		currentCapacity = queue.getCapacity();
		for (int i = 0; i < 100; ++i) {
			queue.enqueue(i);
			currentCapacity--;
			assertEquals("Resizing too often (inefficient)", currentCapacity,
					queue.getCapacity());
		}
	}

but when I am changing the value of

for (int i = 0; i < 7; ++i)

it is still complaining and it fails only when I run the code

[Anissa Pary]

Anissa Pary wrote:

Jeff Verdegan wrote:

Anissa Pary wrote:Sorry I have made a mistake and printed wrong stuff this six mistakes was from another program and here it is just a failure...

Okay, so, what exact errors are you getting here and on which exact lines are they occurring?

it is saying runs:6/6 errors:0 failures: 1
junit.framework.AssertionFailedError: Resizing too often (inefficient) expected: <-1> but was <13> at CircularArrayQueueTest.testResize(CircularArrayQueueTest.java:122). So, it means

assertEquals("Resizing too often (inefficient)", currentCapacity,queue.getCapacity());

in the method:

public void testResize() {
		CircularArrayQueue queue = new CircularArrayQueue();
		assertTrue("Initial capacity too large", queue.getCapacity() <= 1024);
		for (int i = 0; i < 7; ++i) {
			queue.enqueue(i);
		}
		int currentCapacity = queue.getCapacity();
		while (currentCapacity > 0) {
			queue.enqueue(9);
			currentCapacity--;
			assertEquals("Array size should not change", currentCapacity,
					queue.getCapacity());
		}
		assertTrue("Should have reached capacity", queue.getCapacity() == 0);
		queue.enqueue(42);
		assertTrue("Should have resized array",
				currentCapacity < queue.getCapacity());
		currentCapacity = queue.getCapacity();
		for (int i = 0; i < 100; ++i) {
			queue.enqueue(i);
			currentCapacity--;
			assertEquals("Resizing too often (inefficient)", currentCapacity,
					queue.getCapacity());
		}
	}

but when I am changing the value of

for (int i = 0; i < 7; ++i)

it is still complaining and it fails only when I run the code

OK get it working now anyway thanks for looking in my code!