JCCollection.java

package ee.esutoniagodesu.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

/**
 * class for various static operations with lists
 */
public final class JCCollection {

    public static void print(List out) {
        System.out.println("----------");
        if (out != null && out.size() > 0) {
            for (Object anOut : out) {
                System.out.println(anOut);
            }
        }
        System.out.println("----------");
    }

    /**
     * joins list with string delimiter
     */
    public static String join(List list, String delimiter) {
        String result = "";

        for (int i = 0; i < list.size(); i++) {
            if (i != 0) {
                result += delimiter;
            }
            result += list.get(i).toString();
        }

        return result;
    }

    /**
     * merges two lists and loses recurring elements
     */
    public static List<String> merge(List<String> a, List<String> b) {
        List<String> result = new ArrayList<>(a);
        result.removeAll(b);
        result.addAll(b);
        return result;
    }

    public static String toString(Collection col) {
        if (col == null) return null;
        StringBuilder result = new StringBuilder("[");
        for (Object p : col) {
            if (result.length() > 1)
                result.append(", ");
            result.append(p);
        }
        result.append("]");
        return result.toString();
    }

    @SafeVarargs
    public static <T> Collection<T> collectionSum(Collection<T>... carr) {
        if (carr == null || carr.length < 1) return null;
        Collection<T> result = null;
        for (Collection<T> p : carr) {
            if (result == null && p != null) {
                result = p;
            } else if (p != null) {
                result.addAll(p);
            }
        }
        return result;
    }

    public static List<Integer> toIntList(String commaSeparated) {
        String[] arr = commaSeparated.split(",");
        List<Integer> result = new ArrayList<>();
        for (String p : arr) {
            result.add(Integer.parseInt(p));
        }
        return result;
    }
}