com.carlomicieli.jtrains.value.objects.Length.java Source code

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Here is the source code for com.carlomicieli.jtrains.value.objects.Length.java

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/*
 * Copyright 2014 the original author or authors.
 *
 * 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.carlomicieli.jtrains.value.objects;

import com.carlomicieli.jtrains.util.Helpers;
import org.springframework.util.Assert;

import java.text.DecimalFormat;
import java.util.Objects;

/**
 * @author Carlo Micieli
 */
public final class Length {
    public final static MeasureUnit MILLIMETERS = millimetersUnit();
    public final static MeasureUnit INCHES = inchesUnit();

    private final static double MM_TO_INCHES = 0.0393700787;
    private final static double INCHES_TO_MM = 25.4;
    private final DecimalNumber mm;
    private final DecimalNumber inches;

    private Length(double m, double i) {
        this(DecimalNumber.valueOf(m), DecimalNumber.valueOf(i));
    }

    private Length(DecimalNumber mm, DecimalNumber inches) {
        Assert.isTrue(mm.isPositive());
        Assert.isTrue(inches.isPositive());

        this.mm = mm;
        this.inches = inches;
    }

    public static Length valueOf(double val, MeasureUnit unit) {
        return new Length(unit.toMillimeters(val), unit.toInches(val));
    }

    public double mm() {
        return mm.doubleValue();
    }

    public double inches() {
        return inches.doubleValue();
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == this)
            return true;
        if (!(obj instanceof Length))
            return false;

        Length that = (Length) obj;
        return Objects.equals(this.mm, that.mm) && Objects.equals(this.inches, that.inches);
    }

    @Override
    public int hashCode() {
        return Objects.hash(this.mm, this.inches);
    }

    @Override
    public String toString() {
        return Helpers.toStringBuilder(Length.class, sb -> sb.add("mm", mm).add("in", inches));
    }

    private static interface MeasureUnit {
        double toInches(double v);

        double toMillimeters(double v);
    }

    private static MeasureUnit millimetersUnit() {
        return new MeasureUnit() {
            @Override
            public double toInches(double v) {
                return round(v * MM_TO_INCHES);
            }

            @Override
            public double toMillimeters(double v) {
                return v;
            }
        };
    }

    private static MeasureUnit inchesUnit() {
        return new MeasureUnit() {
            @Override
            public double toInches(double v) {
                return v;
            }

            @Override
            public double toMillimeters(double v) {
                return round(v * INCHES_TO_MM);
            }
        };
    }

    private static double round(double v) {
        DecimalFormat df = new DecimalFormat("#.##");
        return Double.valueOf(df.format(v));
    }
}