Arrays.java

/*******************************************************************************
 * Copyright (c) 2012-2017 Codenvy, S.A.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Codenvy, S.A. - initial API and implementation
 *******************************************************************************/
package org.eclipse.che.ide.util;

import com.google.common.annotations.Beta;
import com.google.common.base.Objects;
import com.google.common.collect.ObjectArrays;

import static com.google.common.base.Preconditions.checkArgument;
import static java.util.Arrays.copyOf;

/**
 * Utility methods to operate with arrays.
 *
 * @author Vlad Zhukovskyi
 * @since 4.3.0
 */
@Beta
public class Arrays {

    /**
     * Checks where given {@code array} is {@code null} or empty.
     *
     * @param array
     *         the array to check
     * @param <T>
     *         any type of the given array
     * @return {@code true} if given array is null or empty, otherwise {@code false}
     * @since 4.3.0
     */
    public static <T> boolean isNullOrEmpty(T[] array) {
        return array == null || array.length == 0;
    }

    /**
     * Adds the given {@code element} to the tail of given {@code array}.
     *
     * @param array
     *         the array to which {@code element} should be inserted
     * @param element
     *         {@code element} to insert
     * @param <T>
     *         type of given {@code array}
     * @return the copy of given {@code array} with added {@code element}
     * @throws IllegalArgumentException
     *         in case if given {@code arrays} is null
     * @since 4.3.0
     */
    public static <T> T[] add(T[] array, T element) {
        checkArgument(array != null, "Input array is null");

        final int index = array.length;

        array = java.util.Arrays.copyOf(array, index + 1);
        array[index] = element;

        return array;
    }

    /**
     * Checks if given {@code element} exists in {@code array}.
     *
     * @param array
     *         arrays to check
     * @param element
     *         element to check for existence
     * @param <T>
     *         type of given {@code array}
     * @return {@code true} if input {@code element} exists in array, otherwise {@code false}
     * @throws IllegalArgumentException
     *         in case if given {@code array} is null
     * @since 4.3.0
     */
    public static <T> boolean contains(T[] array, T element) {
        return indexOf(array, element) != -1;
    }

    /**
     * Returns the index of the first occurrence of the element {@code o} in given {@code array},
     * or -1 if there is no such element exists.
     *
     * @param array
     *         input array
     * @param o
     *         element to search for
     * @param <T>
     *         type of given {@code array}
     * @return the index of the first occurrence of the specified element in this {@code array}, otherwise -1
     * @throws IllegalArgumentException
     *         in case if given {@code array} is null
     * @since 4.3.0
     */
    public static <T> int indexOf(T[] array, T o) {
        checkArgument(array != null, "Input array is null");

        for (int index = 0; index < array.length; index++) {
            if (Objects.equal(o, array[index])) {
                return index;
            }
        }

        return -1;
    }

    /**
     * Remove from array {@code o1} all elements which exists in {@code o2} if {@code retain} flag is set to {@code false}.
     * If argument {@code retain} is set to {@code true}, then in result collection will be common elements from both arrays.
     *
     * @param o1
     *         input array
     * @param o2
     *         array, elements of which should be removed from the {@code o2} array
     * @param retain
     *         true if operation should be performed with retain algorithm, false means that from {@code o1} should be removed all elements
     *         that contains in {@code o2}
     * @param <T>
     *         type of given {@code o1} and {@code o2}
     * @return new array, which contains elements based on operation type
     * @throws IllegalArgumentException
     *         in case if given arrays null
     * @since 4.3.0
     */
    public static <T> T[] removeAll(T[] o1, T[] o2, boolean retain) {
        checkArgument(o1 != null && o2 != null, "Input arrays are null");

        T[] retained = retain ? ObjectArrays.newArray(o1, 0) : o1;

        for (int index = 0; index < o1.length; index++) {
            if (indexOf(o2, o1[index]) != -1) {
                retained = retain ? add(retained, o1[index]) : remove(retained, o1[index]);
            }
        }

        return retained;
    }

    /**
     * Removes the first occurrence of the specified {@code element} from the given {@code array},
     * if it is present and returns the copy of modified array.
     *
     * @param array
     *         the array from which {@code element} should be removed
     * @param element
     *         {@code element} to remove
     * @param <T>
     *         type of given {@code array}
     * @return the copy of given {@code array} without removed {@code element}
     * @throws IllegalArgumentException
     *         in case if given {@code arrays} is null
     * @since 4.3.0
     */
    public static <T> T[] remove(T[] array, T element) {
        checkArgument(array != null, "Input array is null");

        T[] modified = copyOf(array, array.length);

        int size = modified.length;
        int index = indexOf(modified, element);
        int numMoved = modified.length - index - 1;
        if (numMoved > 0) {
            System.arraycopy(modified, index + 1, modified, index, numMoved);
        }

        return copyOf(modified, --size);
    }
}