com.github.htfv.utils.el.internal.StringFunctions.java Source code

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Here is the source code for com.github.htfv.utils.el.internal.StringFunctions.java

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/*
 * Copyright 2013 htfv (Aliaksei Lahachou)
 *
 * 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.github.htfv.utils.el.internal;

import java.lang.reflect.Method;

import org.apache.commons.lang3.StringUtils;

public class StringFunctions {
    /**
     * Caches reference to the {@link StringFunctions#concat} method.
     *
     * @author htfv (Aliaksei Lahachou)
     */
    public static class Concat {
        /**
         * Reference to the {@link StringFunctions#concat} method.
         */
        public static final Method INSTANCE = getMethod("concat", String[].class);
    }

    /**
     * Caches reference to the {@link StringFunctions#join} method.
     *
     * @author htfv (Aliaksei Lahachou)
     */
    public static class Join {
        /**
         * Reference to the {@link StringFunctions#join} method.
         */
        public static final Method INSTANCE = getMethod("join", String.class, String[].class);
    }

    /**
     * Concatenates array of strings without a separator, ignoring any empty and
     * {@code null} strings.
     *
     * @param strings
     *            the array of strings to join.
     *
     * @return the joined string.
     */
    public static String concat(final String... strings) {
        final StringBuilder joinedString = new StringBuilder();

        for (int i = 0; i < strings.length; i += 1) {
            final String string = strings[i];

            if (StringUtils.isNotEmpty(string)) {
                joinedString.append(string);
            }
        }

        return joinedString.toString();
    }

    /**
     * Returns a {@link Method} object which reflects a public method of the
     * {@link DefaultFunctionMapper} class.
     *
     * @param name
     *            the name of the method.
     * @param parameterTypes
     *            the list of parameters.
     *
     * @return the {@code Method} object that matches the specified {@code name}
     *         and {@code parameterTypes} or {@code null} if method was not
     *         found.
     */
    private static Method getMethod(final String name, final Class<?>... parameterTypes) {
        try {
            return StringFunctions.class.getMethod(name, parameterTypes);
        } catch (final NoSuchMethodException e) {
            return null;
        }
    }

    /**
     * Joins array of strings with a separator, ignoring any empty and
     * {@code null} strings.
     *
     * @param separator
     *            the separator string to use.
     * @param strings
     *            the array of strings to join.
     *
     * @return the joined string.
     */
    public static String join(final String separator, final String... strings) {
        final StringBuilder joinedString = new StringBuilder();
        final int stringCount = strings.length;

        int i = 0;

        for (; i < stringCount; i += 1) {
            final String string = strings[i];

            if (StringUtils.isNotEmpty(string)) {
                joinedString.append(string);
                break;
            }
        }

        for (i += 1; i < stringCount; i += 1) {
            final String string = strings[i];

            if (StringUtils.isNotEmpty(string)) {
                joinedString.append(separator).append(string);
            }
        }

        return joinedString.toString();
    }
}