arrayutils.java

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	public static void checkIsArray(final Object array,
			final boolean allowEnumeration) {
		if (!allowEnumeration && (array instanceof Enumeration)) {
			// throw the exception
		} else {
			if (isArray(array))
				return;
		}
		throw new IllegalArgumentException(
				"not an array: " + array == null ? "null" : array //$NON-NLS-1$ //$NON-NLS-2$
						.getClass().toString());
	}

	private static final byte[] BYTE = new byte[0];

	private static final boolean[] BOOL = new boolean[0];

	private static final long[] LONG = new long[0];

	private static final int[] INT = new int[0];

	private static final Object[] OBJ = new Object[0];

	private static final short[] SHORT = new short[0];

	/**
	 * <p>
	 * Returns length of given array.
	 * </p>
	 * <p>
	 * Note: there is no way to get number of items for Enumeration but to walk
	 * through it. This effectively 'destroys' given enumeration instance as it
	 * is no longer usable.
	 * </p>
	 * 
	 * @param array
	 *            the array to check. See {@link #arrayToEnumeration(Object)}
	 *            for details.
	 * @return length of an array.
	 */
	public static int getLength(final Object array) {
		checkIsArray(array, true);
		final Class c = array.getClass();
		if (c.isInstance(BYTE))
			return ((byte[]) array).length;
		else if (c.isInstance(BOOL))
			return ((boolean[]) array).length;
		else if (c.isInstance(LONG))
			return ((long[]) array).length;
		else if (c.isInstance(INT))
			return ((int[]) array).length;
		else if (c.isInstance(OBJ))
			return ((Object[]) array).length;
		else if (c.isInstance(SHORT))
			return ((short[]) array).length;
		else if (array instanceof Vector)
			return ((Vector) array).size();
		else if (array instanceof Queue)
			return ((Queue) array).occupiedSlots();
		else {
			int i = 0;
			for (; ((Enumeration) array).hasMoreElements();) {
				i++;
			}
			return i;
		}
	}

	/**
	 * Retrieves item from given array.
	 * 
	 * @param array
	 *            the array instance. For details please see
	 *            {@link #arrayToEnumeration(Object)}.
	 * @param index
	 *            the index of array.
	 * @return object at given index.
	 */
	public static Object getElementAt(Object array, int index) {
		checkIsArray(array, false);
		final Class c = array.getClass();
		if (c.isInstance(BYTE))
			return new Byte(((byte[]) array)[index]);
		else if (c.isInstance(BOOL))
			return new Boolean(((boolean[]) array)[index]);
		else if (c.isInstance(LONG))
			return new Long(((long[]) array)[index]);
		else if (c.isInstance(INT))
			return new Integer(((int[]) array)[index]);
		else if (c.isInstance(OBJ))
			return ((Object[]) array)[index];
		else if (c.isInstance(SHORT))
			return new Short(((short[]) array)[index]);
		else if (array instanceof Vector)
			return ((Vector) array).elementAt(index);
		else
			return ((Queue) array).peek(index);
	}

	/**
	 * Sets item into given array.
	 * 
	 * @param array
	 *            the array instance. For details please see
	 *            {@link #arrayToEnumeration(Object)}. Note that {@link Queue}
	 *            does not support setting of arbitrary item.
	 * @param index
	 *            the index of array.
	 * @param object
	 *            object to set.
	 */
	public static void setElementAt(Object array, int index, final Object object) {
		checkIsArray(array, false);
		final Class c = array.getClass();
		if (c.isInstance(BYTE))
			((byte[]) array)[index] = ((Byte) object).byteValue();
		else if (c.isInstance(BOOL))
			((boolean[]) array)[index] = ((Boolean) object).booleanValue();
		else if (c.isInstance(LONG))
			((long[]) array)[index] = ((Long) object).longValue();
		else if (c.isInstance(INT))
			((int[]) array)[index] = ((Integer) object).intValue();
		else if (c.isInstance(OBJ))
			((Object[]) array)[index] = object;
		else if (c.isInstance(SHORT))
			((short[]) array)[index] = ((Short) object).shortValue();
		else if (array instanceof Vector)
			((Vector) array).setElementAt(object, index);
		else
			throw new IllegalArgumentException("Queue is not supported"); //$NON-NLS-1$
	}

	/**
	 * Converts given object into an enumeration. For details see
	 * {@link #arrayToEnumeration(Object)}.
	 * 
	 * @author Martin Vysny
	 */
	public static final class ArrayEnumeration implements Enumeration {
		/**
		 * Constructor.
		 * 
		 * @param array
		 *            array instance.
		 */
		ArrayEnumeration(final Object array) {
			super();
			this.array = array;
			length = getLength(array);
		}

		/**
		 * The array.
		 */
		private final Object array;

		/**
		 * The length of given array.
		 */
		private final int length;

		/**
		 * Item to be offered by the enumeration.
		 */
		private int currentItem = 0;

		/*
		 * (non-Javadoc)
		 * 
		 * @see java.util.Enumeration#hasMoreElements()
		 */
		public boolean hasMoreElements() {
			return currentItem < length;
		}

		/*
		 * (non-Javadoc)
		 * 
		 * @see java.util.Enumeration#nextElement()
		 */
		public Object nextElement() {
			if (!hasMoreElements())
				throw new NoSuchElementException();
			return getElementAt(array, currentItem++);
		}
	}

	/**
	 * Clones given array. For details please see
	 * {@link #arrayToEnumeration(Object)}.
	 * 
	 * @param array
	 *            the array to clone. {@link Enumeration}s are not supported.
	 * @param deep
	 *            if <code>true</code> then sub-arrays are cloned aswell. Note
	 *            that if you introduce a nesting cycle the function will
	 *            recurse until stack overflow is reached.
	 * @return array of same class but cloned. Returns <code>null</code> if
	 *         <code>null</code> array was given.
	 */
	public static Object clone(final Object array, final boolean deep) {
		if (array == null)
			return null;
		if (array instanceof Queue) {
			if (!deep)
				return new Queue((Queue) array);
			final Queue q = (Queue) array;
			final Queue result = new Queue(q.bufferSize);
			for (final Enumeration e = q.getEnumeration(); e.hasMoreElements();) {
				Object obj = e.nextElement();
				if (isArray(obj))
					obj = clone(obj, true);
				result.offer(obj);
			}
			return result;
		}
		final Class c = array.getClass();
		if (c.isInstance(BYTE)) {
			final byte[] a = (byte[]) array;
			final byte[] result = new byte[a.length];
			for (int i = 0; i < a.length; i++)
				result[i] = a[i];
			return result;
		} else if (c.isInstance(BOOL)) {
			final boolean[] a = (boolean[]) array;
			final boolean[] result = new boolean[a.length];
			for (int i = 0; i < a.length; i++)
				result[i] = a[i];
			return result;
		} else if (c.isInstance(LONG)) {
			final long[] a = (long[]) array;
			final long[] result = new long[a.length];
			for (int i = 0; i < a.length; i++)
				result[i] = a[i];
			return result;
		} else if (c.isInstance(INT)) {
			final int[] a = (int[]) array;
			final int[] result = new int[a.length];
			for (int i = 0; i < a.length; i++)
				result[i] = a[i];
			return result;
		} else if (c.isInstance(OBJ)) {
			final Object[] a = (Object[]) array;
			final Object[] result = new Object[a.length];
			for (int i = 0; i < a.length; i++) {
				Object obj = a[i];
				if (deep && isArray(obj))
					obj = clone(obj, true);
				result[i] = obj;
			}
			return result;
		} else if (c.isInstance(SHORT)) {
			final short[] a = (short[]) array;
			final short[] result = new short[a.length];
			for (int i = 0; i < a.length; i++)
				result[i] = a[i];
			return result;
		} else if (array instanceof Vector) {
			final Vector a = (Vector) array;
			final Vector result = new Vector(a.size());
			for (int i = 0; i < a.size(); i++) {
				Object obj = a.elementAt(i);
				if (deep && isArray(obj))
					obj = clone(obj, true);
				result.addElement(obj);
			}
			return result;
		} else
			throw new IllegalArgumentException("Unsupported array class: " //$NON-NLS-1$
					+ c.getName());
	}

	/**
	 * Converts given array to a string representation.
	 * 
	 * @param array
	 *            the array to convert.
	 * @return string representation of the array.
	 */
	public static String arrayToString(final Object array) {
		if (array == null)
			return "null"; //$NON-NLS-1$
		checkIsArray(array, true);
		final StringBuffer result = new StringBuffer("["); //$NON-NLS-1$
		for (final Enumeration e = arrayToEnumeration(array); e
				.hasMoreElements();) {
			final Object obj = e.nextElement();
			if (isArray(obj)) {
				result.append(arrayToString(obj));
			} else {
				if (obj == null)
					result.append("null"); //$NON-NLS-1$
				else
					result.append(obj);
			}
			if (e.hasMoreElements())
				result.append(", "); //$NON-NLS-1$
		}
		result.append(']');
		return result.toString();
	}
}