001// Copyright 2006, 2007 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.ioc;
016
017/**
018 * Provides access to a messages catalog, a set of properties files that provide localized messages for a particular
019 * locale. The message catalog consists of keys and values and follows the semantics of a Java {@link
020 * java.util.ResourceBundle} with some changes.
021 */
022public interface Messages
023{
024    /**
025     * Returns true if the bundle contains the named key.
026     */
027    boolean contains(String key);
028
029    /**
030     * Returns the localized message for the given key. If catalog does not contain such a key, then a modified version
031     * of the key is returned (converted to upper case and enclosed in brackets).
032     *
033     * @param key
034     * @return localized message for key, or placeholder
035     */
036    String get(String key);
037
038    /**
039     * Returns a formatter for the message, which can be used to substitute arguments (as per {@link
040     * java.util.Formatter}).
041     *
042     * @param key
043     * @return formattable object
044     */
045    MessageFormatter getFormatter(String key);
046
047    /**
048     * Convienience for accessing a formatter and formatting a localized message with arguments.
049     */
050
051    String format(String key, Object... args);
052}