modules/luni/src/main/java/org/apache/harmony/luni/util/Msg.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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 org.apache.harmony.luni.util;


import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

import org.apache.harmony.luni.util.MsgHelp;

/**
 * This class retrieves strings from a resource bundle and returns them,
 * formatting them with MessageFormat when required.
 * <p>
 * It is used by the system classes to provide national language support, by
 * looking up messages in the <code>
 *    org.apache.harmony.luni.util.ExternalMessages
 * </code>
 * resource bundle. Note that if this file is not available, or an invalid key
 * is looked up, or resource bundle support is not available, the key itself
 * will be returned as the associated message. This means that the <em>KEY</em>
 * should a reasonable human-readable (english) string.
 * 
 */
public class Msg {

	// ResourceBundle holding the system messages.
	static private ResourceBundle bundle = null;

	static {
		// Attempt to load the messages.
		try {
			bundle = MsgHelp.setLocale(Locale.getDefault(),
					"org.apache.harmony.luni.util.ExternalMessages");
		} catch (Throwable e) {
			e.printStackTrace();
		}
	}

	/**
	 * Retrieves a message which has no arguments.
	 * 
	 * @param msg
	 *            String the key to look up.
	 * @return String the message for that key in the system message bundle.
	 */
	static public String getString(String msg) {
		if (bundle == null)
			return msg;
		try {
			return bundle.getString(msg);
		} catch (MissingResourceException e) {
			return msg;
		}
	}

	/**
	 * Retrieves a message which takes 1 argument.
	 * 
	 * @param msg
	 *            String the key to look up.
	 * @param arg
	 *            Object the object to insert in the formatted output.
	 * @return String the message for that key in the system message bundle.
	 */
	static public String getString(String msg, Object arg) {
		return getString(msg, new Object[] { arg });
	}

	/**
	 * Retrieves a message which takes 1 integer argument.
	 * 
	 * @param msg
	 *            String the key to look up.
	 * @param arg
	 *            int the integer to insert in the formatted output.
	 * @return String the message for that key in the system message bundle.
	 */
	static public String getString(String msg, int arg) {
		return getString(msg, new Object[] { Integer.toString(arg) });
	}

	/**
	 * Retrieves a message which takes 1 character argument.
	 * 
	 * @param msg
	 *            String the key to look up.
	 * @param arg
	 *            char the character to insert in the formatted output.
	 * @return String the message for that key in the system message bundle.
	 */
	static public String getString(String msg, char arg) {
		return getString(msg, new Object[] { String.valueOf(arg) });
	}

	/**
	 * Retrieves a message which takes 2 arguments.
	 * 
	 * @param msg
	 *            String the key to look up.
	 * @param arg1
	 *            Object an object to insert in the formatted output.
	 * @param arg2
	 *            Object another object to insert in the formatted output.
	 * @return String the message for that key in the system message bundle.
	 */
	static public String getString(String msg, Object arg1, Object arg2) {
		return getString(msg, new Object[] { arg1, arg2 });
	}

	/**
	 * Retrieves a message which takes several arguments.
	 * 
	 * @param msg
	 *            String the key to look up.
	 * @param args
	 *            Object[] the objects to insert in the formatted output.
	 * @return String the message for that key in the system message bundle.
	 */
	static public String getString(String msg, Object[] args) {
		String format = msg;

		if (bundle != null) {
			try {
				format = bundle.getString(msg);
			} catch (MissingResourceException e) {
			}
		}

		return MsgHelp.format(format, args);
	}
}