Java tutorial
/* * Copyright (c) 1998, 2014, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* * (C) Copyright IBM Corp. 1998 - All Rights Reserved * * The original version of this source code and documentation is copyrighted * and owned by IBM, Inc. These materials are provided under terms of a * License Agreement between IBM and Sun. This technology is protected by * multiple US and International patents. This notice and attribution to IBM * may not be removed. * */ package java.awt; import java.util.Locale; import java.util.ResourceBundle; /** * The ComponentOrientation class encapsulates the language-sensitive * orientation that is to be used to order the elements of a component * or of text. It is used to reflect the differences in this ordering * between Western alphabets, Middle Eastern (such as Hebrew), and Far * Eastern (such as Japanese). * <p> * Fundamentally, this governs items (such as characters) which are laid out * in lines, with the lines then laid out in a block. This also applies * to items in a widget: for example, in a check box where the box is * positioned relative to the text. * <p> * There are four different orientations used in modern languages * as in the following table.<br> * <pre> * LT RT TL TR * A B C C B A A D G G D A * D E F F E D B E H H E B * G H I I H G C F I I F C * </pre><br> * (In the header, the two-letter abbreviation represents the item direction * in the first letter, and the line direction in the second. For example, * LT means "items left-to-right, lines top-to-bottom", * TL means "items top-to-bottom, lines left-to-right", and so on.) * <p> * The orientations are: * <ul> * <li>LT - Western Europe (optional for Japanese, Chinese, Korean) * <li>RT - Middle East (Arabic, Hebrew) * <li>TR - Japanese, Chinese, Korean * <li>TL - Mongolian * </ul> * Components whose view and controller code depends on orientation * should use the {@code isLeftToRight()} and * {@code isHorizontal()} methods to * determine their behavior. They should not include switch-like * code that keys off of the constants, such as: * <pre> * if (orientation == LEFT_TO_RIGHT) { * ... * } else if (orientation == RIGHT_TO_LEFT) { * ... * } else { * // Oops * } * </pre> * This is unsafe, since more constants may be added in the future and * since it is not guaranteed that orientation objects will be unique. */ public final class ComponentOrientation implements java.io.Serializable { /* * serialVersionUID */ private static final long serialVersionUID = -4113291392143563828L; // Internal constants used in the implementation private static final int UNK_BIT = 1; private static final int HORIZ_BIT = 2; private static final int LTR_BIT = 4; /** * Items run left to right and lines flow top to bottom * Examples: English, French. */ public static final ComponentOrientation LEFT_TO_RIGHT = new ComponentOrientation(HORIZ_BIT | LTR_BIT); /** * Items run right to left and lines flow top to bottom * Examples: Arabic, Hebrew. */ public static final ComponentOrientation RIGHT_TO_LEFT = new ComponentOrientation(HORIZ_BIT); /** * Indicates that a component's orientation has not been set. * To preserve the behavior of existing applications, * isLeftToRight will return true for this value. */ public static final ComponentOrientation UNKNOWN = new ComponentOrientation(HORIZ_BIT | LTR_BIT | UNK_BIT); /** * Are lines horizontal? * This will return true for horizontal, left-to-right writing * systems such as Roman. * * @return {@code true} if this orientation has horizontal lines */ public boolean isHorizontal() { return (orientation & HORIZ_BIT) != 0; } /** * HorizontalLines: Do items run left-to-right?<br> * Vertical Lines: Do lines run left-to-right?<br> * This will return true for horizontal, left-to-right writing * systems such as Roman. * * @return {@code true} if this orientation is left-to-right */ public boolean isLeftToRight() { return (orientation & LTR_BIT) != 0; } /** * Returns the orientation that is appropriate for the given locale. * * @param locale the specified locale * @return the orientation for the locale */ public static ComponentOrientation getOrientation(Locale locale) { // A more flexible implementation would consult a ResourceBundle // to find the appropriate orientation. Until pluggable locales // are introduced however, the flexibility isn't really needed. // So we choose efficiency instead. String lang = locale.getLanguage(); if ("iw".equals(lang) || "ar".equals(lang) || "fa".equals(lang) || "ur".equals(lang)) { return RIGHT_TO_LEFT; } else { return LEFT_TO_RIGHT; } } /** * Returns the orientation appropriate for the given ResourceBundle's * localization. Three approaches are tried, in the following order: * <ol> * <li>Retrieve a ComponentOrientation object from the ResourceBundle * using the string "Orientation" as the key. * <li>Use the ResourceBundle.getLocale to determine the bundle's * locale, then return the orientation for that locale. * <li>Return the default locale's orientation. * </ol> * * @param bdl the bundle to use * @return the orientation * @deprecated As of J2SE 1.4, use {@link #getOrientation(java.util.Locale)}. */ @Deprecated public static ComponentOrientation getOrientation(ResourceBundle bdl) { ComponentOrientation result = null; try { result = (ComponentOrientation) bdl.getObject("Orientation"); } catch (Exception e) { } if (result == null) { result = getOrientation(bdl.getLocale()); } if (result == null) { result = getOrientation(Locale.getDefault()); } return result; } private int orientation; private ComponentOrientation(int value) { orientation = value; } }