001/*
002 * Copyright (C) 2008 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the License
010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011 * or implied. See the License for the specific language governing permissions and limitations under
012 * the License.
013 */
014
015package com.google.common.primitives;
016
017import static com.google.common.base.Preconditions.checkArgument;
018import static com.google.common.base.Preconditions.checkElementIndex;
019import static com.google.common.base.Preconditions.checkNotNull;
020import static com.google.common.base.Preconditions.checkPositionIndexes;
021import static com.google.common.base.Strings.lenientFormat;
022import static java.lang.Float.NEGATIVE_INFINITY;
023import static java.lang.Float.POSITIVE_INFINITY;
024
025import com.google.common.annotations.GwtCompatible;
026import com.google.common.annotations.GwtIncompatible;
027import com.google.common.base.Converter;
028import java.io.Serializable;
029import java.util.AbstractList;
030import java.util.Arrays;
031import java.util.Collection;
032import java.util.Collections;
033import java.util.Comparator;
034import java.util.List;
035import java.util.RandomAccess;
036import javax.annotation.CheckForNull;
037
038/**
039 * Static utility methods pertaining to {@code float} primitives, that are not already found in
040 * either {@link Float} or {@link Arrays}.
041 *
042 * <p>See the Guava User Guide article on <a
043 * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>.
044 *
045 * @author Kevin Bourrillion
046 * @since 1.0
047 */
048@GwtCompatible(emulated = true)
049@ElementTypesAreNonnullByDefault
050public final class Floats extends FloatsMethodsForWeb {
051  private Floats() {}
052
053  /**
054   * The number of bytes required to represent a primitive {@code float} value.
055   *
056   * <p><b>Java 8+ users:</b> use {@link Float#BYTES} instead.
057   *
058   * @since 10.0
059   */
060  public static final int BYTES = Float.SIZE / Byte.SIZE;
061
062  /**
063   * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Float)
064   * value).hashCode()}.
065   *
066   * <p><b>Java 8+ users:</b> use {@link Float#hashCode(float)} instead.
067   *
068   * @param value a primitive {@code float} value
069   * @return a hash code for the value
070   */
071  public static int hashCode(float value) {
072    // TODO(kevinb): is there a better way, that's still gwt-safe?
073    return ((Float) value).hashCode();
074  }
075
076  /**
077   * Compares the two specified {@code float} values using {@link Float#compare(float, float)}. You
078   * may prefer to invoke that method directly; this method exists only for consistency with the
079   * other utilities in this package.
080   *
081   * <p><b>Note:</b> this method simply delegates to the JDK method {@link Float#compare}. It is
082   * provided for consistency with the other primitive types, whose compare methods were not added
083   * to the JDK until JDK 7.
084   *
085   * @param a the first {@code float} to compare
086   * @param b the second {@code float} to compare
087   * @return the result of invoking {@link Float#compare(float, float)}
088   */
089  public static int compare(float a, float b) {
090    return Float.compare(a, b);
091  }
092
093  /**
094   * Returns {@code true} if {@code value} represents a real number. This is equivalent to, but not
095   * necessarily implemented as, {@code !(Float.isInfinite(value) || Float.isNaN(value))}.
096   *
097   * <p><b>Java 8+ users:</b> use {@link Float#isFinite(float)} instead.
098   *
099   * @since 10.0
100   */
101  public static boolean isFinite(float value) {
102    return NEGATIVE_INFINITY < value && value < POSITIVE_INFINITY;
103  }
104
105  /**
106   * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}. Note
107   * that this always returns {@code false} when {@code target} is {@code NaN}.
108   *
109   * @param array an array of {@code float} values, possibly empty
110   * @param target a primitive {@code float} value
111   * @return {@code true} if {@code array[i] == target} for some value of {@code i}
112   */
113  public static boolean contains(float[] array, float target) {
114    for (float value : array) {
115      if (value == target) {
116        return true;
117      }
118    }
119    return false;
120  }
121
122  /**
123   * Returns the index of the first appearance of the value {@code target} in {@code array}. Note
124   * that this always returns {@code -1} when {@code target} is {@code NaN}.
125   *
126   * @param array an array of {@code float} values, possibly empty
127   * @param target a primitive {@code float} value
128   * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no
129   *     such index exists.
130   */
131  public static int indexOf(float[] array, float target) {
132    return indexOf(array, target, 0, array.length);
133  }
134
135  // TODO(kevinb): consider making this public
136  private static int indexOf(float[] array, float target, int start, int end) {
137    for (int i = start; i < end; i++) {
138      if (array[i] == target) {
139        return i;
140      }
141    }
142    return -1;
143  }
144
145  /**
146   * Returns the start position of the first occurrence of the specified {@code target} within
147   * {@code array}, or {@code -1} if there is no such occurrence.
148   *
149   * <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array,
150   * i, i + target.length)} contains exactly the same elements as {@code target}.
151   *
152   * <p>Note that this always returns {@code -1} when {@code target} contains {@code NaN}.
153   *
154   * @param array the array to search for the sequence {@code target}
155   * @param target the array to search for as a sub-sequence of {@code array}
156   */
157  public static int indexOf(float[] array, float[] target) {
158    checkNotNull(array, "array");
159    checkNotNull(target, "target");
160    if (target.length == 0) {
161      return 0;
162    }
163
164    outer:
165    for (int i = 0; i < array.length - target.length + 1; i++) {
166      for (int j = 0; j < target.length; j++) {
167        if (array[i + j] != target[j]) {
168          continue outer;
169        }
170      }
171      return i;
172    }
173    return -1;
174  }
175
176  /**
177   * Returns the index of the last appearance of the value {@code target} in {@code array}. Note
178   * that this always returns {@code -1} when {@code target} is {@code NaN}.
179   *
180   * @param array an array of {@code float} values, possibly empty
181   * @param target a primitive {@code float} value
182   * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no
183   *     such index exists.
184   */
185  public static int lastIndexOf(float[] array, float target) {
186    return lastIndexOf(array, target, 0, array.length);
187  }
188
189  // TODO(kevinb): consider making this public
190  private static int lastIndexOf(float[] array, float target, int start, int end) {
191    for (int i = end - 1; i >= start; i--) {
192      if (array[i] == target) {
193        return i;
194      }
195    }
196    return -1;
197  }
198
199  /**
200   * Returns the least value present in {@code array}, using the same rules of comparison as {@link
201   * Math#min(float, float)}.
202   *
203   * @param array a <i>nonempty</i> array of {@code float} values
204   * @return the value present in {@code array} that is less than or equal to every other value in
205   *     the array
206   * @throws IllegalArgumentException if {@code array} is empty
207   */
208  @GwtIncompatible(
209      "Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.")
210  public static float min(float... array) {
211    checkArgument(array.length > 0);
212    float min = array[0];
213    for (int i = 1; i < array.length; i++) {
214      min = Math.min(min, array[i]);
215    }
216    return min;
217  }
218
219  /**
220   * Returns the greatest value present in {@code array}, using the same rules of comparison as
221   * {@link Math#max(float, float)}.
222   *
223   * @param array a <i>nonempty</i> array of {@code float} values
224   * @return the value present in {@code array} that is greater than or equal to every other value
225   *     in the array
226   * @throws IllegalArgumentException if {@code array} is empty
227   */
228  @GwtIncompatible(
229      "Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.")
230  public static float max(float... array) {
231    checkArgument(array.length > 0);
232    float max = array[0];
233    for (int i = 1; i < array.length; i++) {
234      max = Math.max(max, array[i]);
235    }
236    return max;
237  }
238
239  /**
240   * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}.
241   *
242   * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned
243   * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code
244   * value} is greater than {@code max}, {@code max} is returned.
245   *
246   * @param value the {@code float} value to constrain
247   * @param min the lower bound (inclusive) of the range to constrain {@code value} to
248   * @param max the upper bound (inclusive) of the range to constrain {@code value} to
249   * @throws IllegalArgumentException if {@code min > max}
250   * @since 21.0
251   */
252  public static float constrainToRange(float value, float min, float max) {
253    // avoid auto-boxing by not using Preconditions.checkArgument(); see Guava issue 3984
254    // Reject NaN by testing for the good case (min <= max) instead of the bad (min > max).
255    if (min <= max) {
256      return Math.min(Math.max(value, min), max);
257    }
258    throw new IllegalArgumentException(
259        lenientFormat("min (%s) must be less than or equal to max (%s)", min, max));
260  }
261
262  /**
263   * Returns the values from each provided array combined into a single array. For example, {@code
264   * concat(new float[] {a, b}, new float[] {}, new float[] {c}} returns the array {@code {a, b,
265   * c}}.
266   *
267   * @param arrays zero or more {@code float} arrays
268   * @return a single array containing all the values from the source arrays, in order
269   */
270  public static float[] concat(float[]... arrays) {
271    int length = 0;
272    for (float[] array : arrays) {
273      length += array.length;
274    }
275    float[] result = new float[length];
276    int pos = 0;
277    for (float[] array : arrays) {
278      System.arraycopy(array, 0, result, pos, array.length);
279      pos += array.length;
280    }
281    return result;
282  }
283
284  private static final class FloatConverter extends Converter<String, Float>
285      implements Serializable {
286    static final Converter<String, Float> INSTANCE = new FloatConverter();
287
288    @Override
289    protected Float doForward(String value) {
290      return Float.valueOf(value);
291    }
292
293    @Override
294    protected String doBackward(Float value) {
295      return value.toString();
296    }
297
298    @Override
299    public String toString() {
300      return "Floats.stringConverter()";
301    }
302
303    private Object readResolve() {
304      return INSTANCE;
305    }
306
307    private static final long serialVersionUID = 1;
308  }
309
310  /**
311   * Returns a serializable converter object that converts between strings and floats using {@link
312   * Float#valueOf} and {@link Float#toString()}.
313   *
314   * @since 16.0
315   */
316  public static Converter<String, Float> stringConverter() {
317    return FloatConverter.INSTANCE;
318  }
319
320  /**
321   * Returns an array containing the same values as {@code array}, but guaranteed to be of a
322   * specified minimum length. If {@code array} already has a length of at least {@code minLength},
323   * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is
324   * returned, containing the values of {@code array}, and zeroes in the remaining places.
325   *
326   * @param array the source array
327   * @param minLength the minimum length the returned array must guarantee
328   * @param padding an extra amount to "grow" the array by if growth is necessary
329   * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative
330   * @return an array containing the values of {@code array}, with guaranteed minimum length {@code
331   *     minLength}
332   */
333  public static float[] ensureCapacity(float[] array, int minLength, int padding) {
334    checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
335    checkArgument(padding >= 0, "Invalid padding: %s", padding);
336    return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array;
337  }
338
339  /**
340   * Returns a string containing the supplied {@code float} values, converted to strings as
341   * specified by {@link Float#toString(float)}, and separated by {@code separator}. For example,
342   * {@code join("-", 1.0f, 2.0f, 3.0f)} returns the string {@code "1.0-2.0-3.0"}.
343   *
344   * <p>Note that {@link Float#toString(float)} formats {@code float} differently in GWT. In the
345   * previous example, it returns the string {@code "1-2-3"}.
346   *
347   * @param separator the text that should appear between consecutive values in the resulting string
348   *     (but not at the start or end)
349   * @param array an array of {@code float} values, possibly empty
350   */
351  public static String join(String separator, float... array) {
352    checkNotNull(separator);
353    if (array.length == 0) {
354      return "";
355    }
356
357    // For pre-sizing a builder, just get the right order of magnitude
358    StringBuilder builder = new StringBuilder(array.length * 12);
359    builder.append(array[0]);
360    for (int i = 1; i < array.length; i++) {
361      builder.append(separator).append(array[i]);
362    }
363    return builder.toString();
364  }
365
366  /**
367   * Returns a comparator that compares two {@code float} arrays <a
368   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
369   * compares, using {@link #compare(float, float)}), the first pair of values that follow any
370   * common prefix, or when one array is a prefix of the other, treats the shorter array as the
371   * lesser. For example, {@code [] < [1.0f] < [1.0f, 2.0f] < [2.0f]}.
372   *
373   * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
374   * support only identity equality), but it is consistent with {@link Arrays#equals(float[],
375   * float[])}.
376   *
377   * @since 2.0
378   */
379  public static Comparator<float[]> lexicographicalComparator() {
380    return LexicographicalComparator.INSTANCE;
381  }
382
383  private enum LexicographicalComparator implements Comparator<float[]> {
384    INSTANCE;
385
386    @Override
387    public int compare(float[] left, float[] right) {
388      int minLength = Math.min(left.length, right.length);
389      for (int i = 0; i < minLength; i++) {
390        int result = Float.compare(left[i], right[i]);
391        if (result != 0) {
392          return result;
393        }
394      }
395      return left.length - right.length;
396    }
397
398    @Override
399    public String toString() {
400      return "Floats.lexicographicalComparator()";
401    }
402  }
403
404  /**
405   * Sorts the elements of {@code array} in descending order.
406   *
407   * <p>Note that this method uses the total order imposed by {@link Float#compare}, which treats
408   * all NaN values as equal and 0.0 as greater than -0.0.
409   *
410   * @since 23.1
411   */
412  public static void sortDescending(float[] array) {
413    checkNotNull(array);
414    sortDescending(array, 0, array.length);
415  }
416
417  /**
418   * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
419   * exclusive in descending order.
420   *
421   * <p>Note that this method uses the total order imposed by {@link Float#compare}, which treats
422   * all NaN values as equal and 0.0 as greater than -0.0.
423   *
424   * @since 23.1
425   */
426  public static void sortDescending(float[] array, int fromIndex, int toIndex) {
427    checkNotNull(array);
428    checkPositionIndexes(fromIndex, toIndex, array.length);
429    Arrays.sort(array, fromIndex, toIndex);
430    reverse(array, fromIndex, toIndex);
431  }
432
433  /**
434   * Reverses the elements of {@code array}. This is equivalent to {@code
435   * Collections.reverse(Floats.asList(array))}, but is likely to be more efficient.
436   *
437   * @since 23.1
438   */
439  public static void reverse(float[] array) {
440    checkNotNull(array);
441    reverse(array, 0, array.length);
442  }
443
444  /**
445   * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
446   * exclusive. This is equivalent to {@code
447   * Collections.reverse(Floats.asList(array).subList(fromIndex, toIndex))}, but is likely to be
448   * more efficient.
449   *
450   * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or
451   *     {@code toIndex > fromIndex}
452   * @since 23.1
453   */
454  public static void reverse(float[] array, int fromIndex, int toIndex) {
455    checkNotNull(array);
456    checkPositionIndexes(fromIndex, toIndex, array.length);
457    for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) {
458      float tmp = array[i];
459      array[i] = array[j];
460      array[j] = tmp;
461    }
462  }
463
464  /**
465   * Performs a right rotation of {@code array} of "distance" places, so that the first element is
466   * moved to index "distance", and the element at index {@code i} ends up at index {@code (distance
467   * + i) mod array.length}. This is equivalent to {@code Collections.rotate(Floats.asList(array),
468   * distance)}, but is considerably faster and avoids allocation and garbage collection.
469   *
470   * <p>The provided "distance" may be negative, which will rotate left.
471   *
472   * @since 32.0.0
473   */
474  public static void rotate(float[] array, int distance) {
475    rotate(array, distance, 0, array.length);
476  }
477
478  /**
479   * Performs a right rotation of {@code array} between {@code fromIndex} inclusive and {@code
480   * toIndex} exclusive. This is equivalent to {@code
481   * Collections.rotate(Floats.asList(array).subList(fromIndex, toIndex), distance)}, but is
482   * considerably faster and avoids allocations and garbage collection.
483   *
484   * <p>The provided "distance" may be negative, which will rotate left.
485   *
486   * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or
487   *     {@code toIndex > fromIndex}
488   * @since 32.0.0
489   */
490  public static void rotate(float[] array, int distance, int fromIndex, int toIndex) {
491    // See Ints.rotate for more details about possible algorithms here.
492    checkNotNull(array);
493    checkPositionIndexes(fromIndex, toIndex, array.length);
494    if (array.length <= 1) {
495      return;
496    }
497
498    int length = toIndex - fromIndex;
499    // Obtain m = (-distance mod length), a non-negative value less than "length". This is how many
500    // places left to rotate.
501    int m = -distance % length;
502    m = (m < 0) ? m + length : m;
503    // The current index of what will become the first element of the rotated section.
504    int newFirstIndex = m + fromIndex;
505    if (newFirstIndex == fromIndex) {
506      return;
507    }
508
509    reverse(array, fromIndex, newFirstIndex);
510    reverse(array, newFirstIndex, toIndex);
511    reverse(array, fromIndex, toIndex);
512  }
513
514  /**
515   * Returns an array containing each value of {@code collection}, converted to a {@code float}
516   * value in the manner of {@link Number#floatValue}.
517   *
518   * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}.
519   * Calling this method is as thread-safe as calling that method.
520   *
521   * @param collection a collection of {@code Number} instances
522   * @return an array containing the same values as {@code collection}, in the same order, converted
523   *     to primitives
524   * @throws NullPointerException if {@code collection} or any of its elements is null
525   * @since 1.0 (parameter was {@code Collection<Float>} before 12.0)
526   */
527  public static float[] toArray(Collection<? extends Number> collection) {
528    if (collection instanceof FloatArrayAsList) {
529      return ((FloatArrayAsList) collection).toFloatArray();
530    }
531
532    Object[] boxedArray = collection.toArray();
533    int len = boxedArray.length;
534    float[] array = new float[len];
535    for (int i = 0; i < len; i++) {
536      // checkNotNull for GWT (do not optimize)
537      array[i] = ((Number) checkNotNull(boxedArray[i])).floatValue();
538    }
539    return array;
540  }
541
542  /**
543   * Returns a fixed-size list backed by the specified array, similar to {@link
544   * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to
545   * set a value to {@code null} will result in a {@link NullPointerException}.
546   *
547   * <p>The returned list maintains the values, but not the identities, of {@code Float} objects
548   * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for
549   * the returned list is unspecified.
550   *
551   * <p>The returned list may have unexpected behavior if it contains {@code NaN}, or if {@code NaN}
552   * is used as a parameter to any of its methods.
553   *
554   * <p>The returned list is serializable.
555   *
556   * @param backingArray the array to back the list
557   * @return a list view of the array
558   */
559  public static List<Float> asList(float... backingArray) {
560    if (backingArray.length == 0) {
561      return Collections.emptyList();
562    }
563    return new FloatArrayAsList(backingArray);
564  }
565
566  @GwtCompatible
567  private static class FloatArrayAsList extends AbstractList<Float>
568      implements RandomAccess, Serializable {
569    final float[] array;
570    final int start;
571    final int end;
572
573    FloatArrayAsList(float[] array) {
574      this(array, 0, array.length);
575    }
576
577    FloatArrayAsList(float[] array, int start, int end) {
578      this.array = array;
579      this.start = start;
580      this.end = end;
581    }
582
583    @Override
584    public int size() {
585      return end - start;
586    }
587
588    @Override
589    public boolean isEmpty() {
590      return false;
591    }
592
593    @Override
594    public Float get(int index) {
595      checkElementIndex(index, size());
596      return array[start + index];
597    }
598
599    @Override
600    public boolean contains(@CheckForNull Object target) {
601      // Overridden to prevent a ton of boxing
602      return (target instanceof Float) && Floats.indexOf(array, (Float) target, start, end) != -1;
603    }
604
605    @Override
606    public int indexOf(@CheckForNull Object target) {
607      // Overridden to prevent a ton of boxing
608      if (target instanceof Float) {
609        int i = Floats.indexOf(array, (Float) target, start, end);
610        if (i >= 0) {
611          return i - start;
612        }
613      }
614      return -1;
615    }
616
617    @Override
618    public int lastIndexOf(@CheckForNull Object target) {
619      // Overridden to prevent a ton of boxing
620      if (target instanceof Float) {
621        int i = Floats.lastIndexOf(array, (Float) target, start, end);
622        if (i >= 0) {
623          return i - start;
624        }
625      }
626      return -1;
627    }
628
629    @Override
630    public Float set(int index, Float element) {
631      checkElementIndex(index, size());
632      float oldValue = array[start + index];
633      // checkNotNull for GWT (do not optimize)
634      array[start + index] = checkNotNull(element);
635      return oldValue;
636    }
637
638    @Override
639    public List<Float> subList(int fromIndex, int toIndex) {
640      int size = size();
641      checkPositionIndexes(fromIndex, toIndex, size);
642      if (fromIndex == toIndex) {
643        return Collections.emptyList();
644      }
645      return new FloatArrayAsList(array, start + fromIndex, start + toIndex);
646    }
647
648    @Override
649    public boolean equals(@CheckForNull Object object) {
650      if (object == this) {
651        return true;
652      }
653      if (object instanceof FloatArrayAsList) {
654        FloatArrayAsList that = (FloatArrayAsList) object;
655        int size = size();
656        if (that.size() != size) {
657          return false;
658        }
659        for (int i = 0; i < size; i++) {
660          if (array[start + i] != that.array[that.start + i]) {
661            return false;
662          }
663        }
664        return true;
665      }
666      return super.equals(object);
667    }
668
669    @Override
670    public int hashCode() {
671      int result = 1;
672      for (int i = start; i < end; i++) {
673        result = 31 * result + Floats.hashCode(array[i]);
674      }
675      return result;
676    }
677
678    @Override
679    public String toString() {
680      StringBuilder builder = new StringBuilder(size() * 12);
681      builder.append('[').append(array[start]);
682      for (int i = start + 1; i < end; i++) {
683        builder.append(", ").append(array[i]);
684      }
685      return builder.append(']').toString();
686    }
687
688    float[] toFloatArray() {
689      return Arrays.copyOfRange(array, start, end);
690    }
691
692    private static final long serialVersionUID = 0;
693  }
694
695  /**
696   * Parses the specified string as a single-precision floating point value. The ASCII character
697   * {@code '-'} (<code>'&#92;u002D'</code>) is recognized as the minus sign.
698   *
699   * <p>Unlike {@link Float#parseFloat(String)}, this method returns {@code null} instead of
700   * throwing an exception if parsing fails. Valid inputs are exactly those accepted by {@link
701   * Float#valueOf(String)}, except that leading and trailing whitespace is not permitted.
702   *
703   * <p>This implementation is likely to be faster than {@code Float.parseFloat} if many failures
704   * are expected.
705   *
706   * @param string the string representation of a {@code float} value
707   * @return the floating point value represented by {@code string}, or {@code null} if {@code
708   *     string} has a length of zero or cannot be parsed as a {@code float} value
709   * @throws NullPointerException if {@code string} is {@code null}
710   * @since 14.0
711   */
712  @GwtIncompatible // regular expressions
713  @CheckForNull
714  public static Float tryParse(String string) {
715    if (Doubles.FLOATING_POINT_PATTERN.matcher(string).matches()) {
716      // TODO(lowasser): could be potentially optimized, but only with
717      // extensive testing
718      try {
719        return Float.parseFloat(string);
720      } catch (NumberFormatException e) {
721        // Float.parseFloat has changed specs several times, so fall through
722        // gracefully
723      }
724    }
725    return null;
726  }
727}