Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/*
 * Copyright (C) 2015-2016 Emanuel Moecklin
 *
 * 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.
 */

import java.text.Bidi;

import java.util.Locale;

public class Main {
    /**
     * This method determines if the direction of a substring is right-to-left.
     * If the string is empty that determination is based on the default system language
     * Locale.getDefault().
     * The method can handle invalid substring definitions (start > end etc.), in which case the
     * method returns False.
     *
     * @return True if the text direction is right-to-left, false otherwise.
     */
    public static boolean isRTL(CharSequence s, int start, int end) {
        if (s == null || s.length() == 0) {
            // empty string --> determine the direction from the default language
            return isRTL(Locale.getDefault());
        }

        if (start == end) {
            // if no character is selected we need to expand the selection
            start = Math.max(0, --start);
            if (start == end) {
                end = Math.min(s.length(), ++end);
            }
        }

        try {
            Bidi bidi = new Bidi(s.subSequence(start, end).toString(), Bidi.DIRECTION_DEFAULT_LEFT_TO_RIGHT);
            return !bidi.baseIsLeftToRight();
        } catch (IndexOutOfBoundsException e) {
            return false;
        }
    }

    private static boolean isRTL(Locale locale) {
        int directionality = Character.getDirectionality(locale.getDisplayName().charAt(0));
        return directionality == Character.DIRECTIONALITY_RIGHT_TO_LEFT
                || directionality == Character.DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC;
    }
}