| /* |
| * Copyright (C) 2008 The Guava 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.google.common.primitives; |
| |
| import static com.google.common.base.Preconditions.checkArgument; |
| import static com.google.common.base.Preconditions.checkElementIndex; |
| import static com.google.common.base.Preconditions.checkNotNull; |
| import static com.google.common.base.Preconditions.checkPositionIndexes; |
| import static com.google.common.base.Strings.lenientFormat; |
| import static java.lang.Double.NEGATIVE_INFINITY; |
| import static java.lang.Double.POSITIVE_INFINITY; |
| |
| import com.google.common.annotations.Beta; |
| import com.google.common.annotations.GwtCompatible; |
| import com.google.common.annotations.GwtIncompatible; |
| import com.google.common.base.Converter; |
| import java.io.Serializable; |
| import java.util.AbstractList; |
| import java.util.Arrays; |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.Comparator; |
| import java.util.List; |
| import java.util.RandomAccess; |
| import java.util.Spliterator; |
| import java.util.Spliterators; |
| import org.checkerframework.checker.nullness.qual.Nullable; |
| |
| /** |
| * Static utility methods pertaining to {@code double} primitives, that are not already found in |
| * either {@link Double} or {@link Arrays}. |
| * |
| * <p>See the Guava User Guide article on <a |
| * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>. |
| * |
| * @author Kevin Bourrillion |
| * @since 1.0 |
| */ |
| @GwtCompatible(emulated = true) |
| public final class Doubles extends DoublesMethodsForWeb { |
| private Doubles() {} |
| |
| /** |
| * The number of bytes required to represent a primitive {@code double} value. |
| * |
| * <p><b>Java 8 users:</b> use {@link Double#BYTES} instead. |
| * |
| * @since 10.0 |
| */ |
| public static final int BYTES = Double.SIZE / Byte.SIZE; |
| |
| /** |
| * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Double) |
| * value).hashCode()}. |
| * |
| * <p><b>Java 8 users:</b> use {@link Double#hashCode(double)} instead. |
| * |
| * @param value a primitive {@code double} value |
| * @return a hash code for the value |
| */ |
| public static int hashCode(double value) { |
| return ((Double) value).hashCode(); |
| // TODO(kevinb): do it this way when we can (GWT problem): |
| // long bits = Double.doubleToLongBits(value); |
| // return (int) (bits ^ (bits >>> 32)); |
| } |
| |
| /** |
| * Compares the two specified {@code double} values. The sign of the value returned is the same as |
| * that of <code>((Double) a).{@linkplain Double#compareTo compareTo}(b)</code>. As with that |
| * method, {@code NaN} is treated as greater than all other values, and {@code 0.0 > -0.0}. |
| * |
| * <p><b>Note:</b> this method simply delegates to the JDK method {@link Double#compare}. It is |
| * provided for consistency with the other primitive types, whose compare methods were not added |
| * to the JDK until JDK 7. |
| * |
| * @param a the first {@code double} to compare |
| * @param b the second {@code double} to compare |
| * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is |
| * greater than {@code b}; or zero if they are equal |
| */ |
| public static int compare(double a, double b) { |
| return Double.compare(a, b); |
| } |
| |
| /** |
| * Returns {@code true} if {@code value} represents a real number. This is equivalent to, but not |
| * necessarily implemented as, {@code !(Double.isInfinite(value) || Double.isNaN(value))}. |
| * |
| * <p><b>Java 8 users:</b> use {@link Double#isFinite(double)} instead. |
| * |
| * @since 10.0 |
| */ |
| public static boolean isFinite(double value) { |
| return NEGATIVE_INFINITY < value && value < POSITIVE_INFINITY; |
| } |
| |
| /** |
| * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}. Note |
| * that this always returns {@code false} when {@code target} is {@code NaN}. |
| * |
| * @param array an array of {@code double} values, possibly empty |
| * @param target a primitive {@code double} value |
| * @return {@code true} if {@code array[i] == target} for some value of {@code i} |
| */ |
| public static boolean contains(double[] array, double target) { |
| for (double value : array) { |
| if (value == target) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| /** |
| * Returns the index of the first appearance of the value {@code target} in {@code array}. Note |
| * that this always returns {@code -1} when {@code target} is {@code NaN}. |
| * |
| * @param array an array of {@code double} values, possibly empty |
| * @param target a primitive {@code double} value |
| * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no |
| * such index exists. |
| */ |
| public static int indexOf(double[] array, double target) { |
| return indexOf(array, target, 0, array.length); |
| } |
| |
| // TODO(kevinb): consider making this public |
| private static int indexOf(double[] array, double target, int start, int end) { |
| for (int i = start; i < end; i++) { |
| if (array[i] == target) { |
| return i; |
| } |
| } |
| return -1; |
| } |
| |
| /** |
| * Returns the start position of the first occurrence of the specified {@code target} within |
| * {@code array}, or {@code -1} if there is no such occurrence. |
| * |
| * <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array, |
| * i, i + target.length)} contains exactly the same elements as {@code target}. |
| * |
| * <p>Note that this always returns {@code -1} when {@code target} contains {@code NaN}. |
| * |
| * @param array the array to search for the sequence {@code target} |
| * @param target the array to search for as a sub-sequence of {@code array} |
| */ |
| public static int indexOf(double[] array, double[] target) { |
| checkNotNull(array, "array"); |
| checkNotNull(target, "target"); |
| if (target.length == 0) { |
| return 0; |
| } |
| |
| outer: |
| for (int i = 0; i < array.length - target.length + 1; i++) { |
| for (int j = 0; j < target.length; j++) { |
| if (array[i + j] != target[j]) { |
| continue outer; |
| } |
| } |
| return i; |
| } |
| return -1; |
| } |
| |
| /** |
| * Returns the index of the last appearance of the value {@code target} in {@code array}. Note |
| * that this always returns {@code -1} when {@code target} is {@code NaN}. |
| * |
| * @param array an array of {@code double} values, possibly empty |
| * @param target a primitive {@code double} value |
| * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no |
| * such index exists. |
| */ |
| public static int lastIndexOf(double[] array, double target) { |
| return lastIndexOf(array, target, 0, array.length); |
| } |
| |
| // TODO(kevinb): consider making this public |
| private static int lastIndexOf(double[] array, double target, int start, int end) { |
| for (int i = end - 1; i >= start; i--) { |
| if (array[i] == target) { |
| return i; |
| } |
| } |
| return -1; |
| } |
| |
| /** |
| * Returns the least value present in {@code array}, using the same rules of comparison as {@link |
| * Math#min(double, double)}. |
| * |
| * @param array a <i>nonempty</i> array of {@code double} values |
| * @return the value present in {@code array} that is less than or equal to every other value in |
| * the array |
| * @throws IllegalArgumentException if {@code array} is empty |
| */ |
| @GwtIncompatible( |
| "Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.") |
| public static double min(double... array) { |
| checkArgument(array.length > 0); |
| double min = array[0]; |
| for (int i = 1; i < array.length; i++) { |
| min = Math.min(min, array[i]); |
| } |
| return min; |
| } |
| |
| /** |
| * Returns the greatest value present in {@code array}, using the same rules of comparison as |
| * {@link Math#max(double, double)}. |
| * |
| * @param array a <i>nonempty</i> array of {@code double} values |
| * @return the value present in {@code array} that is greater than or equal to every other value |
| * in the array |
| * @throws IllegalArgumentException if {@code array} is empty |
| */ |
| @GwtIncompatible( |
| "Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.") |
| public static double max(double... array) { |
| checkArgument(array.length > 0); |
| double max = array[0]; |
| for (int i = 1; i < array.length; i++) { |
| max = Math.max(max, array[i]); |
| } |
| return max; |
| } |
| |
| /** |
| * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}. |
| * |
| * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned |
| * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code |
| * value} is greater than {@code max}, {@code max} is returned. |
| * |
| * @param value the {@code double} value to constrain |
| * @param min the lower bound (inclusive) of the range to constrain {@code value} to |
| * @param max the upper bound (inclusive) of the range to constrain {@code value} to |
| * @throws IllegalArgumentException if {@code min > max} |
| * @since 21.0 |
| */ |
| @Beta |
| public static double constrainToRange(double value, double min, double max) { |
| // avoid auto-boxing by not using Preconditions.checkArgument(); see Guava issue 3984 |
| // Reject NaN by testing for the good case (min <= max) instead of the bad (min > max). |
| if (min <= max) { |
| return Math.min(Math.max(value, min), max); |
| } |
| throw new IllegalArgumentException( |
| lenientFormat("min (%s) must be less than or equal to max (%s)", min, max)); |
| } |
| |
| /** |
| * Returns the values from each provided array combined into a single array. For example, {@code |
| * concat(new double[] {a, b}, new double[] {}, new double[] {c}} returns the array {@code {a, b, |
| * c}}. |
| * |
| * @param arrays zero or more {@code double} arrays |
| * @return a single array containing all the values from the source arrays, in order |
| */ |
| public static double[] concat(double[]... arrays) { |
| int length = 0; |
| for (double[] array : arrays) { |
| length += array.length; |
| } |
| double[] result = new double[length]; |
| int pos = 0; |
| for (double[] array : arrays) { |
| System.arraycopy(array, 0, result, pos, array.length); |
| pos += array.length; |
| } |
| return result; |
| } |
| |
| private static final class DoubleConverter extends Converter<String, Double> |
| implements Serializable { |
| static final DoubleConverter INSTANCE = new DoubleConverter(); |
| |
| @Override |
| protected Double doForward(String value) { |
| return Double.valueOf(value); |
| } |
| |
| @Override |
| protected String doBackward(Double value) { |
| return value.toString(); |
| } |
| |
| @Override |
| public String toString() { |
| return "Doubles.stringConverter()"; |
| } |
| |
| private Object readResolve() { |
| return INSTANCE; |
| } |
| |
| private static final long serialVersionUID = 1; |
| } |
| |
| /** |
| * Returns a serializable converter object that converts between strings and doubles using {@link |
| * Double#valueOf} and {@link Double#toString()}. |
| * |
| * @since 16.0 |
| */ |
| @Beta |
| public static Converter<String, Double> stringConverter() { |
| return DoubleConverter.INSTANCE; |
| } |
| |
| /** |
| * Returns an array containing the same values as {@code array}, but guaranteed to be of a |
| * specified minimum length. If {@code array} already has a length of at least {@code minLength}, |
| * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is |
| * returned, containing the values of {@code array}, and zeroes in the remaining places. |
| * |
| * @param array the source array |
| * @param minLength the minimum length the returned array must guarantee |
| * @param padding an extra amount to "grow" the array by if growth is necessary |
| * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative |
| * @return an array containing the values of {@code array}, with guaranteed minimum length {@code |
| * minLength} |
| */ |
| public static double[] ensureCapacity(double[] array, int minLength, int padding) { |
| checkArgument(minLength >= 0, "Invalid minLength: %s", minLength); |
| checkArgument(padding >= 0, "Invalid padding: %s", padding); |
| return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array; |
| } |
| |
| /** |
| * Returns a string containing the supplied {@code double} values, converted to strings as |
| * specified by {@link Double#toString(double)}, and separated by {@code separator}. For example, |
| * {@code join("-", 1.0, 2.0, 3.0)} returns the string {@code "1.0-2.0-3.0"}. |
| * |
| * <p>Note that {@link Double#toString(double)} formats {@code double} differently in GWT |
| * sometimes. In the previous example, it returns the string {@code "1-2-3"}. |
| * |
| * @param separator the text that should appear between consecutive values in the resulting string |
| * (but not at the start or end) |
| * @param array an array of {@code double} values, possibly empty |
| */ |
| public static String join(String separator, double... array) { |
| checkNotNull(separator); |
| if (array.length == 0) { |
| return ""; |
| } |
| |
| // For pre-sizing a builder, just get the right order of magnitude |
| StringBuilder builder = new StringBuilder(array.length * 12); |
| builder.append(array[0]); |
| for (int i = 1; i < array.length; i++) { |
| builder.append(separator).append(array[i]); |
| } |
| return builder.toString(); |
| } |
| |
| /** |
| * Returns a comparator that compares two {@code double} arrays <a |
| * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it |
| * compares, using {@link #compare(double, double)}), the first pair of values that follow any |
| * common prefix, or when one array is a prefix of the other, treats the shorter array as the |
| * lesser. For example, {@code [] < [1.0] < [1.0, 2.0] < [2.0]}. |
| * |
| * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays |
| * support only identity equality), but it is consistent with {@link Arrays#equals(double[], |
| * double[])}. |
| * |
| * @since 2.0 |
| */ |
| public static Comparator<double[]> lexicographicalComparator() { |
| return LexicographicalComparator.INSTANCE; |
| } |
| |
| private enum LexicographicalComparator implements Comparator<double[]> { |
| INSTANCE; |
| |
| @Override |
| public int compare(double[] left, double[] right) { |
| int minLength = Math.min(left.length, right.length); |
| for (int i = 0; i < minLength; i++) { |
| int result = Double.compare(left[i], right[i]); |
| if (result != 0) { |
| return result; |
| } |
| } |
| return left.length - right.length; |
| } |
| |
| @Override |
| public String toString() { |
| return "Doubles.lexicographicalComparator()"; |
| } |
| } |
| |
| /** |
| * Sorts the elements of {@code array} in descending order. |
| * |
| * <p>Note that this method uses the total order imposed by {@link Double#compare}, which treats |
| * all NaN values as equal and 0.0 as greater than -0.0. |
| * |
| * @since 23.1 |
| */ |
| public static void sortDescending(double[] array) { |
| checkNotNull(array); |
| sortDescending(array, 0, array.length); |
| } |
| |
| /** |
| * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} |
| * exclusive in descending order. |
| * |
| * <p>Note that this method uses the total order imposed by {@link Double#compare}, which treats |
| * all NaN values as equal and 0.0 as greater than -0.0. |
| * |
| * @since 23.1 |
| */ |
| public static void sortDescending(double[] array, int fromIndex, int toIndex) { |
| checkNotNull(array); |
| checkPositionIndexes(fromIndex, toIndex, array.length); |
| Arrays.sort(array, fromIndex, toIndex); |
| reverse(array, fromIndex, toIndex); |
| } |
| |
| /** |
| * Reverses the elements of {@code array}. This is equivalent to {@code |
| * Collections.reverse(Doubles.asList(array))}, but is likely to be more efficient. |
| * |
| * @since 23.1 |
| */ |
| public static void reverse(double[] array) { |
| checkNotNull(array); |
| reverse(array, 0, array.length); |
| } |
| |
| /** |
| * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} |
| * exclusive. This is equivalent to {@code |
| * Collections.reverse(Doubles.asList(array).subList(fromIndex, toIndex))}, but is likely to be |
| * more efficient. |
| * |
| * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or |
| * {@code toIndex > fromIndex} |
| * @since 23.1 |
| */ |
| public static void reverse(double[] array, int fromIndex, int toIndex) { |
| checkNotNull(array); |
| checkPositionIndexes(fromIndex, toIndex, array.length); |
| for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) { |
| double tmp = array[i]; |
| array[i] = array[j]; |
| array[j] = tmp; |
| } |
| } |
| |
| /** |
| * Returns an array containing each value of {@code collection}, converted to a {@code double} |
| * value in the manner of {@link Number#doubleValue}. |
| * |
| * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}. |
| * Calling this method is as thread-safe as calling that method. |
| * |
| * @param collection a collection of {@code Number} instances |
| * @return an array containing the same values as {@code collection}, in the same order, converted |
| * to primitives |
| * @throws NullPointerException if {@code collection} or any of its elements is null |
| * @since 1.0 (parameter was {@code Collection<Double>} before 12.0) |
| */ |
| public static double[] toArray(Collection<? extends Number> collection) { |
| if (collection instanceof DoubleArrayAsList) { |
| return ((DoubleArrayAsList) collection).toDoubleArray(); |
| } |
| |
| Object[] boxedArray = collection.toArray(); |
| int len = boxedArray.length; |
| double[] array = new double[len]; |
| for (int i = 0; i < len; i++) { |
| // checkNotNull for GWT (do not optimize) |
| array[i] = ((Number) checkNotNull(boxedArray[i])).doubleValue(); |
| } |
| return array; |
| } |
| |
| /** |
| * Returns a fixed-size list backed by the specified array, similar to {@link |
| * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to |
| * set a value to {@code null} will result in a {@link NullPointerException}. |
| * |
| * <p>The returned list maintains the values, but not the identities, of {@code Double} objects |
| * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for |
| * the returned list is unspecified. |
| * |
| * <p>The returned list may have unexpected behavior if it contains {@code NaN}, or if {@code NaN} |
| * is used as a parameter to any of its methods. |
| * |
| * <p><b>Note:</b> when possible, you should represent your data as an {@link |
| * ImmutableDoubleArray} instead, which has an {@link ImmutableDoubleArray#asList asList} view. |
| * |
| * @param backingArray the array to back the list |
| * @return a list view of the array |
| */ |
| public static List<Double> asList(double... backingArray) { |
| if (backingArray.length == 0) { |
| return Collections.emptyList(); |
| } |
| return new DoubleArrayAsList(backingArray); |
| } |
| |
| @GwtCompatible |
| private static class DoubleArrayAsList extends AbstractList<Double> |
| implements RandomAccess, Serializable { |
| final double[] array; |
| final int start; |
| final int end; |
| |
| DoubleArrayAsList(double[] array) { |
| this(array, 0, array.length); |
| } |
| |
| DoubleArrayAsList(double[] array, int start, int end) { |
| this.array = array; |
| this.start = start; |
| this.end = end; |
| } |
| |
| @Override |
| public int size() { |
| return end - start; |
| } |
| |
| @Override |
| public boolean isEmpty() { |
| return false; |
| } |
| |
| @Override |
| public Double get(int index) { |
| checkElementIndex(index, size()); |
| return array[start + index]; |
| } |
| |
| @Override |
| public Spliterator.OfDouble spliterator() { |
| return Spliterators.spliterator(array, start, end, 0); |
| } |
| |
| @Override |
| public boolean contains(Object target) { |
| // Overridden to prevent a ton of boxing |
| return (target instanceof Double) |
| && Doubles.indexOf(array, (Double) target, start, end) != -1; |
| } |
| |
| @Override |
| public int indexOf(Object target) { |
| // Overridden to prevent a ton of boxing |
| if (target instanceof Double) { |
| int i = Doubles.indexOf(array, (Double) target, start, end); |
| if (i >= 0) { |
| return i - start; |
| } |
| } |
| return -1; |
| } |
| |
| @Override |
| public int lastIndexOf(Object target) { |
| // Overridden to prevent a ton of boxing |
| if (target instanceof Double) { |
| int i = Doubles.lastIndexOf(array, (Double) target, start, end); |
| if (i >= 0) { |
| return i - start; |
| } |
| } |
| return -1; |
| } |
| |
| @Override |
| public Double set(int index, Double element) { |
| checkElementIndex(index, size()); |
| double oldValue = array[start + index]; |
| // checkNotNull for GWT (do not optimize) |
| array[start + index] = checkNotNull(element); |
| return oldValue; |
| } |
| |
| @Override |
| public List<Double> subList(int fromIndex, int toIndex) { |
| int size = size(); |
| checkPositionIndexes(fromIndex, toIndex, size); |
| if (fromIndex == toIndex) { |
| return Collections.emptyList(); |
| } |
| return new DoubleArrayAsList(array, start + fromIndex, start + toIndex); |
| } |
| |
| @Override |
| public boolean equals(@Nullable Object object) { |
| if (object == this) { |
| return true; |
| } |
| if (object instanceof DoubleArrayAsList) { |
| DoubleArrayAsList that = (DoubleArrayAsList) object; |
| int size = size(); |
| if (that.size() != size) { |
| return false; |
| } |
| for (int i = 0; i < size; i++) { |
| if (array[start + i] != that.array[that.start + i]) { |
| return false; |
| } |
| } |
| return true; |
| } |
| return super.equals(object); |
| } |
| |
| @Override |
| public int hashCode() { |
| int result = 1; |
| for (int i = start; i < end; i++) { |
| result = 31 * result + Doubles.hashCode(array[i]); |
| } |
| return result; |
| } |
| |
| @Override |
| public String toString() { |
| StringBuilder builder = new StringBuilder(size() * 12); |
| builder.append('[').append(array[start]); |
| for (int i = start + 1; i < end; i++) { |
| builder.append(", ").append(array[i]); |
| } |
| return builder.append(']').toString(); |
| } |
| |
| double[] toDoubleArray() { |
| return Arrays.copyOfRange(array, start, end); |
| } |
| |
| private static final long serialVersionUID = 0; |
| } |
| |
| /** |
| * This is adapted from the regex suggested by {@link Double#valueOf(String)} for prevalidating |
| * inputs. All valid inputs must pass this regex, but it's semantically fine if not all inputs |
| * that pass this regex are valid -- only a performance hit is incurred, not a semantics bug. |
| */ |
| @GwtIncompatible // regular expressions |
| static final |
| java.util.regex.Pattern |
| FLOATING_POINT_PATTERN = fpPattern(); |
| |
| @GwtIncompatible // regular expressions |
| private static |
| java.util.regex.Pattern |
| fpPattern() { |
| /* |
| * We use # instead of * for possessive quantifiers. This lets us strip them out when building |
| * the regex for RE2 (which doesn't support them) but leave them in when building it for |
| * java.util.regex (where we want them in order to avoid catastrophic backtracking). |
| */ |
| String decimal = "(?:\\d+#(?:\\.\\d*#)?|\\.\\d+#)"; |
| String completeDec = decimal + "(?:[eE][+-]?\\d+#)?[fFdD]?"; |
| String hex = "(?:[0-9a-fA-F]+#(?:\\.[0-9a-fA-F]*#)?|\\.[0-9a-fA-F]+#)"; |
| String completeHex = "0[xX]" + hex + "[pP][+-]?\\d+#[fFdD]?"; |
| String fpPattern = "[+-]?(?:NaN|Infinity|" + completeDec + "|" + completeHex + ")"; |
| fpPattern = |
| fpPattern.replace( |
| "#", |
| "+" |
| ); |
| return |
| java.util.regex.Pattern |
| .compile(fpPattern); |
| } |
| |
| /** |
| * Parses the specified string as a double-precision floating point value. The ASCII character |
| * {@code '-'} (<code>'\u002D'</code>) is recognized as the minus sign. |
| * |
| * <p>Unlike {@link Double#parseDouble(String)}, this method returns {@code null} instead of |
| * throwing an exception if parsing fails. Valid inputs are exactly those accepted by {@link |
| * Double#valueOf(String)}, except that leading and trailing whitespace is not permitted. |
| * |
| * <p>This implementation is likely to be faster than {@code Double.parseDouble} if many failures |
| * are expected. |
| * |
| * @param string the string representation of a {@code double} value |
| * @return the floating point value represented by {@code string}, or {@code null} if {@code |
| * string} has a length of zero or cannot be parsed as a {@code double} value |
| * @throws NullPointerException if {@code string} is {@code null} |
| * @since 14.0 |
| */ |
| @Beta |
| @GwtIncompatible // regular expressions |
| public static @Nullable Double tryParse(String string) { |
| if (FLOATING_POINT_PATTERN.matcher(string).matches()) { |
| // TODO(lowasser): could be potentially optimized, but only with |
| // extensive testing |
| try { |
| return Double.parseDouble(string); |
| } catch (NumberFormatException e) { |
| // Double.parseDouble has changed specs several times, so fall through |
| // gracefully |
| } |
| } |
| return null; |
| } |
| } |