UtilsArray.java

/*
 * Copyright 2011-2017 Kay Stenschke
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.kstenschke.shifter.utils;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;

/**
 * Static helper methods for arrays
 */
public class UtilsArray {

    /**
     * Find strings position in array
     *
     * @param haystack String array to search in
     * @param needle   String to be looked for
     * @return int        Found position or -1
     */
    public static int getOffset(String[] haystack, String needle) {
        for (int i = 0; i < haystack.length; i++) {
            if (haystack[i].equals(needle)) {
                return i;
            }
        }

        return -1;
    }

    /**
     * Concatenate strings of given array glued by given delimiter
     *
     * @param stringsArr Array of strings
     * @param glue       Glue in between concatenated strings
     * @return String      All items of stringsArr concatenated w/ glue
     */
    public static String implode(String[] stringsArr, String glue) {
        String out = "";

        for (int i = 0; i < stringsArr.length; i++) {
            out += (i != 0 ? glue : "") + stringsArr[i];
        }

        return out;
    }

    /**
     * This String utility or util method can be used to merge 2 arrays of
     * string values. If the input arrays are like this array1 = {"a", "b" ,
     * "c"} array2 = {"c", "d", "e"} Then the output array will have {"a", "b" ,
     * "c", "d", "e"}
     * <p/>
     * This takes care of eliminating duplicates and checks null values.
     *
     * @param array1 Array of strings
     * @param array2 Array of strings
     * @return array    Merged array containing each of the elements of array1 and array2
     */
    public static String[] mergeArrays(String[] array1, String[] array2) {
        if (array1 == null || array1.length == 0) {
            return array2;
        }
        if (array2 == null || array2.length == 0) {
            return array1;
        }

        List<String> array1List = Arrays.asList(array1);
        List<String> array2List = Arrays.asList(array2);

        List<String> result = new ArrayList<String>(array1List);

        List<String> tmp = new ArrayList<String>(array1List);
        tmp.retainAll(array2List);

        result.removeAll(tmp);
        result.addAll(array2List);

        return result.toArray(new String[result.size()]);
    }

    /**
     * Merge three string arrays
     *
     * @param array1 Array of strings
     * @param array2 Array of strings
     * @param array3 Array of strings
     * @return array    Merged array containing each of the elements of array1, array2 and array3
     */
    public static String[] mergeArrays(String[] array1, String[] array2, String[] array3) {
        return mergeArrays(mergeArrays(array1, array2), array3);
    }

    /**
     * @param  array
     * @return boolean
     */
    public static boolean hasDuplicateItems(String[] array) {
        for (int j = 0; j < array.length; j++) {
            for (int k = j + 1; k < array.length; k++) {
                if (array[k].equals(array[j])) {
                    return true;
                }
            }
        }

        return false;
    }

    /**
     * @param  items
     * @return String[]
     */
    public static String[] reduceDuplicateItems(String[] items) {
        return new HashSet<String>(Arrays.asList(items)).toArray(new String[0]);
    }
}