Create a textual representation of the given collection, separating the individual elements by the provided separator. - Java java.util

Java examples for java.util:Collection Creation

Description

Create a textual representation of the given collection, separating the individual elements by the provided separator.

Demo Code

/*//  ww w  .  j  a  v  a  2  s  . c  o m
   Copyright (C) 2016 HermeneutiX.org

   This file is part of SciToS.

   SciToS is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   SciToS is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with SciToS. If not, see <http://www.gnu.org/licenses/>.
 */
//package com.java2s;

import java.util.Collection;

public class Main {
    public static void main(String[] argv) {
        Collection collection = java.util.Arrays.asList("asdf",
                "java2s.com");
        String separator = "java2s.com";
        System.out.println(toString(collection, separator));
    }

    /**
     * Create a textual representation of the given collection, separating the individual elements by the provided separator.
     * 
     * @param collection
     *            the collection to represent as text
     * @param separator
     *            the separator to include between elements of the collection
     * @return the colleciton's textual representation (or an empty String if the collection is {@code null} or empty)
     */
    public static String toString(final Collection<?> collection,
            final String separator) {
        if (collection == null || collection.isEmpty()) {
            // just return an empty String if the collection is null or empty
            return "";
        }
        if (separator == null) {
            // fall back to the collection's toString() method if no custom separator has been specified
            return collection.toString();
        }
        // guess at a meaningful initial size
        final StringBuilder builder = new StringBuilder(collection.size()
                * (16 + separator.length()));
        boolean addSeparator = false;
        // iterate over the individual elements
        for (final Object collectionElement : collection) {
            if (addSeparator) {
                builder.append(separator);
            } else {
                addSeparator = true;
            }
            // null elements are treated as empty Strings
            if (collectionElement != null) {
                builder.append(collectionElement.toString());
            }
        }
        return builder.toString();
    }
}

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