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Java 1.8+ Library with tons of utility classes required in all projects
/*
* Copyright (C) 2014-2022 Philip Helger (www.helger.com)
* philip[at]helger[dot]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 com.helger.commons.math;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.text.NumberFormat;
import java.util.Locale;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.Immutable;
import com.helger.commons.ValueEnforcer;
import com.helger.commons.annotation.PresentForCodeCoverage;
import com.helger.commons.string.StringHelper;
/**
* Helper class for rounding numeric values in a flexible way.
*
* @author Philip Helger
*/
@Immutable
public final class RoundHelper
{
public enum EDecimalType
{
/** Fixed number representation */
FIX,
/** Exponential number representation */
EXP;
public boolean isFixed ()
{
return this == FIX;
}
public boolean isExponential ()
{
return this == EXP;
}
}
@PresentForCodeCoverage
private static final RoundHelper INSTANCE = new RoundHelper ();
private RoundHelper ()
{}
/**
* Source: http://www.luschny.de/java/doubleformat.html
*
* @param dValue
* The value to be rounded
* @param nScale
* The precision of the decimal scale. If type is
* {@link EDecimalType#FIX} the decimal scale, else the (carrying scale
* - 1). Should be ≥ 0.
* @param eType
* The formatting type. May not be null.
* @param eMode
* The rounding mode to be used. May not be null.
* @return the rounded value according to the specified rules. For NaN and
* infinite values, the input value is returned as is.
*/
public static double getRounded (final double dValue,
@Nonnegative final int nScale,
@Nonnull final RoundingMode eMode,
@Nonnull final EDecimalType eType)
{
ValueEnforcer.isGE0 (nScale, "Scale");
ValueEnforcer.notNull (eMode, "RoundingMode");
ValueEnforcer.notNull (eType, "Type");
if (Double.isNaN (dValue) || Double.isInfinite (dValue))
return dValue;
final BigDecimal bd = BigDecimal.valueOf (dValue);
double ret;
if (eType.isExponential ())
{
final BigDecimal bc = new BigDecimal (bd.unscaledValue (), bd.precision () - 1);
ret = bc.setScale (nScale, eMode).scaleByPowerOfTen (bc.scale () - bd.scale ()).doubleValue ();
}
else
ret = bd.setScale (nScale, eMode).doubleValue ();
return ret;
}
/**
* Round using the {@link RoundingMode#HALF_UP} mode and fix representation
*
* @param dValue
* The value to be rounded
* @param nScale
* The precision scale
* @return the rounded value
*/
public static double getRoundedUpFix (final double dValue, @Nonnegative final int nScale)
{
return getRounded (dValue, nScale, RoundingMode.HALF_UP, EDecimalType.FIX);
}
/**
* Round using the {@link RoundingMode#HALF_UP} mode, fix representation and a
* precision scale of 2.
*
* @param dValue
* The value to be rounded
* @return the rounded value
*/
public static double getRoundedUpFix2 (final double dValue)
{
return getRoundedUpFix (dValue, 2);
}
/**
* Round using the {@link RoundingMode#HALF_EVEN} mode and exponential
* representation
*
* @param dValue
* The value to be rounded
* @param nScale
* The precision scale
* @return the rounded value
*/
public static double getRoundedEvenExp (final double dValue, @Nonnegative final int nScale)
{
return getRounded (dValue, nScale, RoundingMode.HALF_EVEN, EDecimalType.EXP);
}
/**
* Round using the {@link RoundingMode#HALF_EVEN} mode, exponential
* representation and a precision scale of 2.
*
* @param dValue
* The value to be rounded
* @return the rounded value
*/
public static double getRoundedEvenExp2 (final double dValue)
{
return getRoundedEvenExp (dValue, 2);
}
/**
* Source: http://www.luschny.de/java/doubleformat.html
*
* @param dValue
* the value to be formatted
* @param nScale
* The precision of the decimal scale. If type is
* {@link EDecimalType#FIX} the decimal scale, else the (carrying scale
* - 1). Should be ≥ 0.
* @param eType
* The formatting type. May not be null.
* @param aLocale
* The locale to be used for the decimal symbols. May not be
* null.
* @return the string representation of the double value. For NaN and infinite
* values, the return of {@link Double#toString()} is returned.
*/
@Nonnull
public static String getFormatted (final double dValue,
@Nonnegative final int nScale,
@Nonnull final EDecimalType eType,
@Nonnull final Locale aLocale)
{
ValueEnforcer.isGE0 (nScale, "Scale");
ValueEnforcer.notNull (eType, "Type");
ValueEnforcer.notNull (aLocale, "Locale");
if (Double.isNaN (dValue) || Double.isInfinite (dValue))
return Double.toString (dValue);
// Avoid negative scales
final DecimalFormat aDF = (DecimalFormat) NumberFormat.getInstance (aLocale);
aDF.setDecimalFormatSymbols (DecimalFormatSymbols.getInstance (aLocale));
aDF.setMaximumFractionDigits (nScale);
aDF.setMinimumFractionDigits (nScale);
if (eType.isExponential ())
{
String sPattern = "0E0";
if (nScale > 0)
sPattern += '.' + StringHelper.getRepeated ('0', nScale);
aDF.applyPattern (sPattern);
}
else
{
aDF.setGroupingUsed (false);
aDF.setMinimumIntegerDigits (1);
}
return aDF.format (dValue);
}
@Nonnull
public static String getFormattedFix (final double dValue, @Nonnegative final int nScale, final Locale aLocale)
{
return getFormatted (dValue, nScale, EDecimalType.FIX, aLocale);
}
@Nonnull
public static String getFormattedFix2 (final double dValue, final Locale aLocale)
{
return getFormattedFix (dValue, 2, aLocale);
}
@Nonnull
public static String getFormattedExp (final double dValue, @Nonnegative final int nScale, final Locale aLocale)
{
return getFormatted (dValue, nScale, EDecimalType.EXP, aLocale);
}
@Nonnull
public static String getFormattedExp2 (final double dValue, final Locale aLocale)
{
return getFormattedExp (dValue, 2, aLocale);
}
}