de.vandermeer.skb.interfaces.transformers.Integer_To

Introduction

Here is the source code for de.vandermeer.skb.interfaces.transformers.Integer_To_RomanLiteral.java
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/* Copyright 2016 Sven van der Meer <vdmeer.sven@mykolab.com>
 *
 * 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 de.vandermeer.skb.interfaces.transformers;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.Validate;

/**
 * Takes an integer and returns a Roman number literal using upper case ASCII characters.
 *
 * @author     Sven van der Meer &lt;vdmeer.sven@mykolab.com&gt;
 * @version    v0.0.2 build 170502 (02-May-17) for Java 1.8
 * @since      v0.0.1
 */
public interface Integer_To_RomanLiteral extends IsTransformer<Integer, String> {

    /** Array to convert numbers. */
    public final static int[] NUMBERS = { 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 };

    /** Array of Roman number literals. */
    public final static String[] LETTERS = { "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV",
            "I" };

    @Override
    default String transform(Integer number) {
        Validate.notNull(number);
        Validate.validState(-1 < number && number < 4001,
                "Roman literals are only supported between 0 and 4000, number was: " + number);

        String ret = "";
        for (int i = 0; i < NUMBERS.length; i++) {
            while (number >= NUMBERS[i]) {
                ret += LETTERS[i];
                number -= NUMBERS[i];
            }
        }
        return ret;
    }

    /**
     * Creates a transformer that takes an integer and returns a Roman number literal using upper case ASCII characters.
     * @return new transformer
     */
    static Integer_To_RomanLiteral create() {
        return new Integer_To_RomanLiteral() {
        };
    }

    /**
     * Takes an integer and returns a Roman number literal using upper case ASCII characters.
     * @param number input number
     * @return Roman number literal using upper case ASCII characters
     */
    static String convert(Integer number) {
        return StringUtils.join(Integer_To_RomanLiteral.create().transform(number), "");
    }
}
de.vandermeer.skb.interfaces.transformers.Integer_To_RomanLiteral.java Source code

Introduction

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