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All Roads Lead to ROME. ROME is a set of Atom/RSS Java utilities that make it easy to work in Java with most syndication formats. Today it accepts all flavors of RSS (0.90, 0.91, 0.92, 0.93, 0.94, 1.0 and 2.0), Atom 0.3 and Atom 1.0 feeds. Rome includes a set of parsers and generators for the various flavors of feeds, as well as converters to convert from one format to another. The parsers can give you back Java objects that are either specific for the format you want to work with, or a generic normalized SyndFeed object that lets you work on with the data without bothering about the underlying format.

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/*
 *
 * 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.rometools.rome.io.impl;

/**
 * A helper class that parses Numbers out of Strings in a lenient manner.
 *
 * 
 * No method will throw any sort of Exception when parsing a string. All methods accept any Java
 * String or null as legal input, if the input is non null, whitespace will be trimmed first, and
 * then parsing will be attempted.
 * 
 */
public final class NumberParser {

    /**
     * Private constructor to avoid NumberParser instances creation.
     */
    private NumberParser() {
    }

    /**
     * Parses a Long out of a string.
     *
     * @param str string to parse for a Long.
     * @return the Long represented by the given string, It returns null if it was not
     *         possible to parse the the string.
     */
    public static Long parseLong(final String str) {
        if (null != str) {
            try {
                return new Long(Long.parseLong(str.trim()));
            } catch (final Exception e) {
                // :IGNORE:
            }
        }
        return null;
    }

    /**
     * Parse an Integer from a String. If the String is not an integer null is returned and
     * no exception is thrown.
     *
     * @param str the String to parse
     * @return The Integer represented by the String, or null if it could not be parsed.
     */
    public static Integer parseInt(final String str) {
        if (null != str) {
            try {
                return new Integer(Integer.parseInt(str.trim()));
            } catch (final Exception e) {
                // :IGNORE:
            }
        }
        return null;
    }

    /**
     * Parse a Float from a String without exceptions. If the String is not a Float then null is
     * returned
     *
     * @param str the String to parse
     * @return The Float represented by the String, or null if it could not be parsed.
     */
    public static Float parseFloat(final String str) {
        if (null != str) {
            try {
                return new Float(Float.parseFloat(str.trim()));
            } catch (final Exception e) {
                // :IGNORE:
            }
        }
        return null;
    }

    /**
     * Parse a float from a String, with a default value
     *
     * @param str
     * @param def the value to return if the String cannot be parsed
     */
    public static float parseFloat(final String str, final float def) {
        final Float result = parseFloat(str);
        if (result == null) {
            return def;
        } else {
            return result.floatValue();
        }
    }

    /**
     * Parses a long out of a string.
     *
     * @param str string to parse for a long.
     * @param def default value to return if it is not possible to parse the the string.
     * @return the long represented by the given string, or the default.
     */
    public static long parseLong(final String str, final long def) {
        final Long ret = parseLong(str);
        if (ret == null) {
            return def;
        } else {
            return ret.longValue();
        }
    }

}