ArrayUtils.java

package com.firefly.utils.lang;

import java.io.Serializable;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * Utility methods for Array manipulation
 */
public class ArrayUtils implements Cloneable, Serializable {

	private static final long serialVersionUID = 2252854725258539040L;

	public static <T> T[] removeFromArray(T[] array, Object item) {
		if (item == null || array == null)
			return array;
		for (int i = array.length; i-- > 0;) {
			if (item.equals(array[i])) {
				Class<?> c = array == null ? item.getClass() : array.getClass().getComponentType();
				@SuppressWarnings("unchecked")
				T[] na = (T[]) Array.newInstance(c, Array.getLength(array) - 1);
				if (i > 0)
					System.arraycopy(array, 0, na, 0, i);
				if (i + 1 < array.length)
					System.arraycopy(array, i + 1, na, i, array.length - (i + 1));
				return na;
			}
		}
		return array;
	}

	/**
	 * Add element to an array
	 * 
	 * @param array
	 *            The array to add to (or null)
	 * @param item
	 *            The item to add
	 * @param type
	 *            The type of the array (in case of null array)
	 * @return new array with contents of array plus item
	 * @param <T>
	 *            the array entry type
	 */
	public static <T> T[] addToArray(T[] array, T item, Class<?> type) {
		if (array == null) {
			if (type == null && item != null)
				type = item.getClass();
			@SuppressWarnings("unchecked")
			T[] na = (T[]) Array.newInstance(type, 1);
			na[0] = item;
			return na;
		} else {
			T[] na = Arrays.copyOf(array, array.length + 1);
			na[array.length] = item;
			return na;
		}
	}

	/**
	 * Add element to the start of an array
	 * 
	 * @param array
	 *            The array to add to (or null)
	 * @param item
	 *            The item to add
	 * @param type
	 *            The type of the array (in case of null array)
	 * @return new array with contents of array plus item
	 * @param <T>
	 *            the array entry type
	 */
	public static <T> T[] prependToArray(T item, T[] array, Class<?> type) {
		if (array == null) {
			if (type == null && item != null)
				type = item.getClass();
			@SuppressWarnings("unchecked")
			T[] na = (T[]) Array.newInstance(type, 1);
			na[0] = item;
			return na;
		} else {
			Class<?> c = array.getClass().getComponentType();
			@SuppressWarnings("unchecked")
			T[] na = (T[]) Array.newInstance(c, Array.getLength(array) + 1);
			System.arraycopy(array, 0, na, 1, array.length);
			na[0] = item;
			return na;
		}
	}

	/**
	 * @param array
	 *            Any array of object
	 * @return A new <i>modifiable</i> list initialised with the elements from
	 *         <code>array</code>.
	 * @param <E>
	 *            the array entry type
	 */
	public static <E> List<E> asMutableList(E[] array) {
		if (array == null || array.length == 0)
			return new ArrayList<E>();
		return new ArrayList<E>(Arrays.asList(array));
	}

	public static <T> T[] removeNulls(T[] array) {
		for (T t : array) {
			if (t == null) {
				List<T> list = new ArrayList<>();
				for (T t2 : array)
					if (t2 != null)
						list.add(t2);
				return list.toArray(Arrays.copyOf(array, list.size()));
			}
		}
		return array;
	}

}