Java Collection Combine combineValues(Collection<String> values)

Description

One of a pair of methods (the other is splitValues) that is used to combine several un-encoded values into a single delimited, encoded value for placement into a hidden field.

License

Apache License

Parameter

Parameter	Description
values	One or more values which are to be combined

Return

a single HTML-encoded String that contains all the values in such a way that they can be converted back into a Collection of Strings with splitValues().

Declaration

public static String combineValues(Collection<String> values)

Method Source Code

//package com.java2s;
/* Copyright 2005-2006 Tim Fennell
 *
 * 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./*from   w  w  w.  j a v a2  s .c o  m*/
 */

import java.util.Collection;

public class Main {
    private static final String FIELD_DELIMITER_STRING = "||";

    /**
     * One of a pair of methods (the other is splitValues) that is used to combine several
     * un-encoded values into a single delimited, encoded value for placement into a
     * hidden field.
     *
     * @param values One or more values which are to be combined
     * @return a single HTML-encoded String that contains all the values in such a way that
     *         they can be converted back into a Collection of Strings with splitValues().
     */
    public static String combineValues(Collection<String> values) {
        if (values == null || values.size() == 0) {
            return "";
        } else {
            StringBuilder builder = new StringBuilder(values.size() * 30);
            for (String value : values) {
                builder.append(value).append(FIELD_DELIMITER_STRING);
            }

            return encode(builder.toString());
        }
    }

    /**
     * Replaces special HTML characters from the set {@literal [<, >, ", ', &]} with their HTML
     * escape codes.  Note that because the escape codes are multi-character that the returned
     * String could be longer than the one passed in.
     *
     * @param fragment a String fragment that might have HTML special characters in it
     * @return the fragment with special characters escaped
     */
    public static String encode(String fragment) {
        // If the input is null, then the output is null
        if (fragment == null)
            return null;

        StringBuilder builder = new StringBuilder(fragment.length() + 10); // a little wiggle room
        char[] characters = fragment.toCharArray();

        // This loop used to also look for and replace single ticks with &apos; but it
        // turns out that it's not strictly necessary since Stripes uses double-quotes
        // around all form fields, and stupid IE6 will render &apos; verbatim instead
        // of as a single quote.
        for (int i = 0; i < characters.length; ++i) {
            switch (characters[i]) {
            case '<':
                builder.append("&lt;");
                break;
            case '>':
                builder.append("&gt;");
                break;
            case '"':
                builder.append("&quot;");
                break;
            case '&':
                builder.append("&amp;");
                break;
            default:
                builder.append(characters[i]);
            }
        }

        return builder.toString();
    }
}

Java Collection Combine combineValues(Collection values)