Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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 Declaration --------------------------- */ package com.github.jessemull.microflex.util; /* ------------------------------ Dependencies ------------------------------ */ import java.math.BigDecimal; import java.math.BigInteger; import java.util.ArrayList; import java.util.Collection; import java.util.List; import org.apache.commons.lang3.ArrayUtils; /** * This class safely converts (1) double values to lists or arrays of another * numeric type (2) a value from another numeric type to a double. The * utility supports conversion to and from all Java primitives as well as two * immutable data types: * * <table cellspacing="5px" style="text-align:left; margin: 20px;"> * <th><div style="border-bottom: 1px solid black; padding-bottom: 5px;">Primitives<div></th> * <tr> * <td>Byte</td> * </tr> * <tr> * <td>Short</td> * </tr> * <tr> * <td>Int</td> * </tr> * <tr> * <td>Long</td> * </tr> * <tr> * <td>Float</td> * </tr> * <tr> * <td>Double</td> * </tr> * </table> * <table cellspacing="5px" style="text-align:left; margin: 20px;"> * <th><div style="border-bottom: 1px solid black; padding-bottom: 5px;">Immutables<div></th> * <tr> * <td>BigInteger</td> * </tr> * <tr> * <td>BigDecimal</td> * </tr> * </table> * * This class throws an arithmetic exception on overflow. * * @author Jesse L. Mull * @update Updated Oct 18, 2016 * @address http://www.jessemull.com * @email hello@jessemull.com */ public class DoubleUtil { /** * Safely converts a number to a double. Loss of precision may occur. Throws * an arithmetic exception upon overflow. * @param Number number to parse * @return parsed number * @throws ArithmeticException on overflow */ public static double toDouble(Number number) { /* Switch on class and convert to double */ String type = number.getClass().getSimpleName(); double parsed; switch (type) { case "Byte": Byte by = (Byte) number; parsed = by.doubleValue(); break; case "Short": Short sh = (Short) number; parsed = sh.doubleValue(); break; case "Integer": Integer in = (Integer) number; parsed = in.doubleValue(); break; case "Long": Long lo = (Long) number; parsed = lo.doubleValue(); break; case "Float": Float fl = (Float) number; parsed = fl.doubleValue(); break; case "BigInteger": BigInteger bi = (BigInteger) number; if (!OverFlowUtil.doubleOverflow(bi)) { throw new ArithmeticException("Overflow casting " + number + " to a double."); } parsed = bi.doubleValue(); break; case "BigDecimal": BigDecimal bd = (BigDecimal) number; if (!OverFlowUtil.doubleOverflow(bd)) { throw new ArithmeticException("Overflow casting " + number + " to a double."); } parsed = bd.doubleValue(); break; case "Double": Double db = (Double) number; parsed = db.doubleValue(); break; default: throw new IllegalArgumentException( "Invalid type: " + type + "\nData values " + "must extend the abstract Number class."); } return parsed; } /** * Safely converts an object to a double. Loss of precision may occur. Throws * an arithmetic exception upon overflow. * @param Object object to parse * @return parsed object * @throws ArithmeticException on overflow */ public static double toDouble(Object obj) { /* Switch on class and convert to double */ String type = obj.getClass().getSimpleName(); double parsed; switch (type) { case "Byte": Byte by = (Byte) obj; parsed = by.doubleValue(); break; case "Short": Short sh = (Short) obj; parsed = sh.doubleValue(); break; case "Integer": Integer in = (Integer) obj; parsed = in.doubleValue(); break; case "Long": Long lo = (Long) obj; parsed = lo.doubleValue(); break; case "Float": Float fl = (Float) obj; parsed = fl.doubleValue(); break; case "BigInteger": BigInteger bi = (BigInteger) obj; if (!OverFlowUtil.doubleOverflow(bi)) { throw new ArithmeticException("Overflow casting " + obj + " to a double."); } parsed = bi.doubleValue(); break; case "BigDecimal": BigDecimal bd = (BigDecimal) obj; if (!OverFlowUtil.doubleOverflow(bd)) { throw new ArithmeticException("Overflow casting " + obj + " to a double."); } parsed = bd.doubleValue(); break; case "Double": Double db = (Double) obj; parsed = db.doubleValue(); break; default: throw new IllegalArgumentException( "Invalid type: " + type + "\nData values " + "must extend the abstract Number class."); } return parsed; } /** * Converts a list of doubles to a list of bytes. * @param List<Double> list of doubles * @return list of bytes */ public static List<Byte> toByteList(List<Double> list) { List<Byte> byteList = new ArrayList<Byte>(); for (Double val : list) { if (!OverFlowUtil.byteOverflow(val)) { OverFlowUtil.overflowError(val); } byteList.add(val.byteValue()); } return byteList; } /** * Converts a list of doubles to an array of bytes. * @param List<Double> list of doubles * @return array of bytes */ public static byte[] toByteArray(List<Double> list) { for (Double val : list) { if (!OverFlowUtil.byteOverflow(val)) { OverFlowUtil.overflowError(val); } } return ArrayUtils.toPrimitive(list.toArray(new Byte[list.size()])); } /** * Converts a list of doubles to a list of shorts. * @param List<Double> list of doubles * @return list of shorts */ public static List<Short> toShortList(List<Double> list) { List<Short> shortList = new ArrayList<Short>(); for (Double val : list) { if (!OverFlowUtil.shortOverflow(val)) { OverFlowUtil.overflowError(val); } shortList.add(val.shortValue()); } return shortList; } /** * Converts a list of doubles to an array of shorts. * @param List<Double> list of doubles * @return array of shorts */ public static short[] toShortArray(List<Double> list) { for (Double val : list) { if (!OverFlowUtil.shortOverflow(val)) { OverFlowUtil.overflowError(val); } } return ArrayUtils.toPrimitive(list.toArray(new Short[list.size()])); } /** * Converts a list of doubles to a list of integers. * @param List<Double> list of doubles * @return list of shorts */ public static List<Integer> toIntList(List<Double> list) { List<Integer> intList = new ArrayList<Integer>(); for (Double val : list) { if (!OverFlowUtil.intOverflow(val)) { OverFlowUtil.overflowError(val); } intList.add(val.intValue()); } return intList; } /** * Converts a list of doubles to an array of integers. * @param List<Double> list of doubles * @return array of integers */ public static int[] toIntArray(List<Double> list) { for (Double val : list) { if (!OverFlowUtil.intOverflow(val)) { OverFlowUtil.overflowError(val); } } return ArrayUtils.toPrimitive(list.toArray(new Integer[list.size()])); } /** * Converts a list of doubles to a list of longs. * @param List<Double> list of doubles * @return list of longs */ public static List<Long> toLongList(List<Double> list) { List<Long> longList = new ArrayList<Long>(); for (Double val : list) { if (!OverFlowUtil.longOverflow(val)) { OverFlowUtil.overflowError(val); } longList.add(val.longValue()); } return longList; } /** * Converts a list of doubles to an array of longs. * @param List<Double> list of longs * @return array of longs */ public static long[] toLongArray(List<Double> list) { for (Double val : list) { if (!OverFlowUtil.longOverflow(val)) { OverFlowUtil.overflowError(val); } } return ArrayUtils.toPrimitive(list.toArray(new Long[list.size()])); } /** * Converts a list of doubles to a list of floats. * @param List<Double> list of doubles * @return list of floats */ public static List<Float> toFloatList(List<Double> list) { List<Float> floatList = new ArrayList<Float>(); for (Double val : list) { if (!OverFlowUtil.floatOverflow(val)) { OverFlowUtil.overflowError(val); } floatList.add(val.floatValue()); } return floatList; } /** * Converts a list of doubles to an array of floats. * @param List<Double> list of doubles * @return array of floats */ public static float[] toFloatArray(List<Double> list) { for (Double val : list) { if (!OverFlowUtil.floatOverflow(val)) { OverFlowUtil.overflowError(val); } } return ArrayUtils.toPrimitive(list.toArray(new Float[list.size()])); } /** * Converts a collection of numbers to a list of doubles. * @param Collection<Number> the collection * @return the list of doubles */ public static List<Double> toDoubleList(Collection<Number> collection) { List<Double> list = new ArrayList<Double>(); for (Number num : collection) { list.add(toDouble(num)); } return list; } /** * Converts an array of numbers to a list of doubles. * @param Number[] the array * @return the list of doubles */ public static List<Double> toDoubleList(Number[] array) { List<Double> list = new ArrayList<Double>(); for (Number num : array) { list.add(toDouble(num)); } return list; } /** * Converts a list of doubles to an array of doubles. * @param List<Double> list of doubles * @return array of doubles */ public static double[] toDoubleArray(List<Double> list) { return ArrayUtils.toPrimitive(list.toArray(new Double[list.size()])); } /** * Converts a list of doubles to a list of BigIntegers. * @param List<Double> list of doubles * @return list of BigIntegers */ public static List<BigInteger> toBigIntList(List<Double> list) { List<BigInteger> bigIntList = new ArrayList<BigInteger>(); for (Double val : list) { bigIntList.add(new BigDecimal(val).toBigInteger()); } return bigIntList; } /** * Converts a list of doubles to an array of BigIntegers. * @param List<Double> list of doubles * @return array of BigIntegers */ public static BigInteger[] toBigIntArray(List<Double> list) { BigInteger[] toBigInt = new BigInteger[list.size()]; for (int i = 0; i < toBigInt.length; i++) { toBigInt[i] = new BigDecimal(list.get(i)).toBigInteger(); } return toBigInt; } /** * Converts a list of doubles to a list of BigDecimals. * @param List<Double> list of doubles * @return list of BigDecimals */ public static List<BigDecimal> toBigDecimalList(List<Double> list) { List<BigDecimal> bigDecimalList = new ArrayList<BigDecimal>(); for (Double val : list) { bigDecimalList.add(new BigDecimal(val)); } return bigDecimalList; } /** * Converts a list of doubles to an array of BigDecimals. * @param List<Double> list of doubles * @return array of BigDecimal */ public static BigDecimal[] toBigDecimalArray(List<Double> list) { BigDecimal[] toBigDecimal = new BigDecimal[list.size()]; for (int i = 0; i < toBigDecimal.length; i++) { toBigDecimal[i] = new BigDecimal(list.get(i)); } return toBigDecimal; } }