001/*
002 * Copyright (C) 2007 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.base;
016
017import com.google.common.annotations.GwtCompatible;
018import com.google.errorprone.annotations.CanIgnoreReturnValue;
019import javax.annotation.Nullable;
020
021/**
022 * Static convenience methods that help a method or constructor check whether it was invoked
023 * correctly (that is, whether its <i>preconditions</i> were met).
024 *
025 * <p>If the precondition is not met, the {@code Preconditions} method throws an unchecked exception
026 * of a specified type, which helps the method in which the exception was thrown communicate that
027 * its caller has made a mistake. This allows constructs such as
028 *
029 * <pre>{@code
030 * public static double sqrt(double value) {
031 *   if (value < 0) {
032 *     throw new IllegalArgumentException("input is negative: " + value);
033 *   }
034 *   // calculate square root
035 * }
036 * }</pre>
037 *
038 * <p>to be replaced with the more compact
039 *
040 * <pre>{@code
041 * public static double sqrt(double value) {
042 *   checkArgument(value >= 0, "input is negative: %s", value);
043 *   // calculate square root
044 * }
045 * }</pre>
046 *
047 * <p>so that a hypothetical bad caller of this method, such as:
048 *
049 * <pre>{@code
050 *   void exampleBadCaller() {
051 *     double d = sqrt(-1.0);
052 * }
053 * }</pre>
054 *
055 * <p>would be flagged as having called {@code sqrt()} with an illegal argument.
056 *
057 * <h3>Performance</h3>
058 *
059 * <p>Avoid passing message arguments that are expensive to compute; your code will always compute
060 * them, even though they usually won't be needed. If you have such arguments, use the conventional
061 * if/throw idiom instead.
062 *
063 * <p>Depending on your message arguments, memory may be allocated for boxing and varargs array
064 * creation. However, the methods of this class have a large number of overloads that prevent such
065 * allocations in many common cases.
066 *
067 * <p>The message string is not formatted unless the exception will be thrown, so the cost of the
068 * string formatting itself should not be a concern.
069 *
070 * <p>As with any performance concerns, you should consider profiling your code (in a production
071 * environment if possible) before spending a lot of effort on tweaking a particular element.
072 *
073 * <h3>Other types of preconditions</h3>
074 *
075 * <p>Not every type of precondition failure is supported by these methods. Continue to throw
076 * standard JDK exceptions such as {@link java.util.NoSuchElementException} or {@link
077 * UnsupportedOperationException} in the situations they are intended for.
078 *
079 * <h3>Non-preconditions</h3>
080 *
081 * <p>It is of course possible to use the methods of this class to check for invalid conditions
082 * which are <i>not the caller's fault</i>. Doing so is <b>not recommended</b> because it is
083 * misleading to future readers of the code and of stack traces. See <a
084 * href="https://github.com/google/guava/wiki/ConditionalFailuresExplained">Conditional failures
085 * explained</a> in the Guava User Guide for more advice.
086 *
087 * <h3>{@code java.util.Objects.requireNonNull()}</h3>
088 *
089 * <p>Projects which use {@code com.google.common} should generally avoid the use of {@link
090 * java.util.Objects#requireNonNull(Object)}. Instead, use whichever of {@link
091 * #checkNotNull(Object)} or {@link Verify#verifyNotNull(Object)} is appropriate to the situation.
092 * (The same goes for the message-accepting overloads.)
093 *
094 * <h3>Only {@code %s} is supported</h3>
095 *
096 * <p>In {@code Preconditions} error message template strings, only the {@code "%s"} specifier is
097 * supported, not the full range of {@link java.util.Formatter} specifiers.
098 *
099 * <h3>More information</h3>
100 *
101 * <p>See the Guava User Guide on <a
102 * href="https://github.com/google/guava/wiki/PreconditionsExplained">using {@code
103 * Preconditions}</a>.
104 *
105 * @author Kevin Bourrillion
106 * @since 2.0
107 */
108@GwtCompatible
109public final class Preconditions {
110  private Preconditions() {}
111
112  /**
113   * Ensures the truth of an expression involving one or more parameters to the calling method.
114   *
115   * @param expression a boolean expression
116   * @throws IllegalArgumentException if {@code expression} is false
117   */
118  public static void checkArgument(boolean expression) {
119    if (!expression) {
120      throw new IllegalArgumentException();
121    }
122  }
123
124  /**
125   * Ensures the truth of an expression involving one or more parameters to the calling method.
126   *
127   * @param expression a boolean expression
128   * @param errorMessage the exception message to use if the check fails; will be converted to a
129   *     string using {@link String#valueOf(Object)}
130   * @throws IllegalArgumentException if {@code expression} is false
131   */
132  public static void checkArgument(boolean expression, @Nullable Object errorMessage) {
133    if (!expression) {
134      throw new IllegalArgumentException(String.valueOf(errorMessage));
135    }
136  }
137
138  /**
139   * Ensures the truth of an expression involving one or more parameters to the calling method.
140   *
141   * @param expression a boolean expression
142   * @param errorMessageTemplate a template for the exception message should the check fail. The
143   *     message is formed by replacing each {@code %s} placeholder in the template with an
144   *     argument. These are matched by position - the first {@code %s} gets {@code
145   *     errorMessageArgs[0]}, etc. Unmatched arguments will be appended to the formatted message in
146   *     square braces. Unmatched placeholders will be left as-is.
147   * @param errorMessageArgs the arguments to be substituted into the message template. Arguments
148   *     are converted to strings using {@link String#valueOf(Object)}.
149   * @throws IllegalArgumentException if {@code expression} is false
150   * @throws NullPointerException if the check fails and either {@code errorMessageTemplate} or
151   *     {@code errorMessageArgs} is null (don't let this happen)
152   */
153  public static void checkArgument(
154      boolean expression,
155      @Nullable String errorMessageTemplate,
156      @Nullable Object... errorMessageArgs) {
157    if (!expression) {
158      throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
159    }
160  }
161
162  /**
163   * Ensures the truth of an expression involving one or more parameters to the calling method.
164   *
165   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
166   */
167  public static void checkArgument(boolean b, @Nullable String errorMessageTemplate, char p1) {
168    if (!b) {
169      throw new IllegalArgumentException(format(errorMessageTemplate, p1));
170    }
171  }
172
173  /**
174   * Ensures the truth of an expression involving one or more parameters to the calling method.
175   *
176   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
177   */
178  public static void checkArgument(boolean b, @Nullable String errorMessageTemplate, int p1) {
179    if (!b) {
180      throw new IllegalArgumentException(format(errorMessageTemplate, p1));
181    }
182  }
183
184  /**
185   * Ensures the truth of an expression involving one or more parameters to the calling method.
186   *
187   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
188   */
189  public static void checkArgument(boolean b, @Nullable String errorMessageTemplate, long p1) {
190    if (!b) {
191      throw new IllegalArgumentException(format(errorMessageTemplate, p1));
192    }
193  }
194
195  /**
196   * Ensures the truth of an expression involving one or more parameters to the calling method.
197   *
198   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
199   */
200  public static void checkArgument(
201      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1) {
202    if (!b) {
203      throw new IllegalArgumentException(format(errorMessageTemplate, p1));
204    }
205  }
206
207  /**
208   * Ensures the truth of an expression involving one or more parameters to the calling method.
209   *
210   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
211   */
212  public static void checkArgument(
213      boolean b, @Nullable String errorMessageTemplate, char p1, char p2) {
214    if (!b) {
215      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
216    }
217  }
218
219  /**
220   * Ensures the truth of an expression involving one or more parameters to the calling method.
221   *
222   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
223   */
224  public static void checkArgument(
225      boolean b, @Nullable String errorMessageTemplate, char p1, int p2) {
226    if (!b) {
227      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
228    }
229  }
230
231  /**
232   * Ensures the truth of an expression involving one or more parameters to the calling method.
233   *
234   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
235   */
236  public static void checkArgument(
237      boolean b, @Nullable String errorMessageTemplate, char p1, long p2) {
238    if (!b) {
239      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
240    }
241  }
242
243  /**
244   * Ensures the truth of an expression involving one or more parameters to the calling method.
245   *
246   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
247   */
248  public static void checkArgument(
249      boolean b, @Nullable String errorMessageTemplate, char p1, @Nullable Object p2) {
250    if (!b) {
251      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
252    }
253  }
254
255  /**
256   * Ensures the truth of an expression involving one or more parameters to the calling method.
257   *
258   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
259   */
260  public static void checkArgument(
261      boolean b, @Nullable String errorMessageTemplate, int p1, char p2) {
262    if (!b) {
263      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
264    }
265  }
266
267  /**
268   * Ensures the truth of an expression involving one or more parameters to the calling method.
269   *
270   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
271   */
272  public static void checkArgument(
273      boolean b, @Nullable String errorMessageTemplate, int p1, int p2) {
274    if (!b) {
275      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
276    }
277  }
278
279  /**
280   * Ensures the truth of an expression involving one or more parameters to the calling method.
281   *
282   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
283   */
284  public static void checkArgument(
285      boolean b, @Nullable String errorMessageTemplate, int p1, long p2) {
286    if (!b) {
287      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
288    }
289  }
290
291  /**
292   * Ensures the truth of an expression involving one or more parameters to the calling method.
293   *
294   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
295   */
296  public static void checkArgument(
297      boolean b, @Nullable String errorMessageTemplate, int p1, @Nullable Object p2) {
298    if (!b) {
299      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
300    }
301  }
302
303  /**
304   * Ensures the truth of an expression involving one or more parameters to the calling method.
305   *
306   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
307   */
308  public static void checkArgument(
309      boolean b, @Nullable String errorMessageTemplate, long p1, char p2) {
310    if (!b) {
311      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
312    }
313  }
314
315  /**
316   * Ensures the truth of an expression involving one or more parameters to the calling method.
317   *
318   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
319   */
320  public static void checkArgument(
321      boolean b, @Nullable String errorMessageTemplate, long p1, int p2) {
322    if (!b) {
323      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
324    }
325  }
326
327  /**
328   * Ensures the truth of an expression involving one or more parameters to the calling method.
329   *
330   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
331   */
332  public static void checkArgument(
333      boolean b, @Nullable String errorMessageTemplate, long p1, long p2) {
334    if (!b) {
335      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
336    }
337  }
338
339  /**
340   * Ensures the truth of an expression involving one or more parameters to the calling method.
341   *
342   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
343   */
344  public static void checkArgument(
345      boolean b, @Nullable String errorMessageTemplate, long p1, @Nullable Object p2) {
346    if (!b) {
347      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
348    }
349  }
350
351  /**
352   * Ensures the truth of an expression involving one or more parameters to the calling method.
353   *
354   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
355   */
356  public static void checkArgument(
357      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, char p2) {
358    if (!b) {
359      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
360    }
361  }
362
363  /**
364   * Ensures the truth of an expression involving one or more parameters to the calling method.
365   *
366   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
367   */
368  public static void checkArgument(
369      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, int p2) {
370    if (!b) {
371      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
372    }
373  }
374
375  /**
376   * Ensures the truth of an expression involving one or more parameters to the calling method.
377   *
378   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
379   */
380  public static void checkArgument(
381      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, long p2) {
382    if (!b) {
383      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
384    }
385  }
386
387  /**
388   * Ensures the truth of an expression involving one or more parameters to the calling method.
389   *
390   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
391   */
392  public static void checkArgument(
393      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, @Nullable Object p2) {
394    if (!b) {
395      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2));
396    }
397  }
398
399  /**
400   * Ensures the truth of an expression involving one or more parameters to the calling method.
401   *
402   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
403   */
404  public static void checkArgument(
405      boolean b,
406      @Nullable String errorMessageTemplate,
407      @Nullable Object p1,
408      @Nullable Object p2,
409      @Nullable Object p3) {
410    if (!b) {
411      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2, p3));
412    }
413  }
414
415  /**
416   * Ensures the truth of an expression involving one or more parameters to the calling method.
417   *
418   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
419   */
420  public static void checkArgument(
421      boolean b,
422      @Nullable String errorMessageTemplate,
423      @Nullable Object p1,
424      @Nullable Object p2,
425      @Nullable Object p3,
426      @Nullable Object p4) {
427    if (!b) {
428      throw new IllegalArgumentException(format(errorMessageTemplate, p1, p2, p3, p4));
429    }
430  }
431
432  /**
433   * Ensures the truth of an expression involving the state of the calling instance, but not
434   * involving any parameters to the calling method.
435   *
436   * @param expression a boolean expression
437   * @throws IllegalStateException if {@code expression} is false
438   */
439  public static void checkState(boolean expression) {
440    if (!expression) {
441      throw new IllegalStateException();
442    }
443  }
444
445  /**
446   * Ensures the truth of an expression involving the state of the calling instance, but not
447   * involving any parameters to the calling method.
448   *
449   * @param expression a boolean expression
450   * @param errorMessage the exception message to use if the check fails; will be converted to a
451   *     string using {@link String#valueOf(Object)}
452   * @throws IllegalStateException if {@code expression} is false
453   */
454  public static void checkState(boolean expression, @Nullable Object errorMessage) {
455    if (!expression) {
456      throw new IllegalStateException(String.valueOf(errorMessage));
457    }
458  }
459
460  /**
461   * Ensures the truth of an expression involving the state of the calling instance, but not
462   * involving any parameters to the calling method.
463   *
464   * @param expression a boolean expression
465   * @param errorMessageTemplate a template for the exception message should the check fail. The
466   *     message is formed by replacing each {@code %s} placeholder in the template with an
467   *     argument. These are matched by position - the first {@code %s} gets {@code
468   *     errorMessageArgs[0]}, etc. Unmatched arguments will be appended to the formatted message in
469   *     square braces. Unmatched placeholders will be left as-is.
470   * @param errorMessageArgs the arguments to be substituted into the message template. Arguments
471   *     are converted to strings using {@link String#valueOf(Object)}.
472   * @throws IllegalStateException if {@code expression} is false
473   * @throws NullPointerException if the check fails and either {@code errorMessageTemplate} or
474   *     {@code errorMessageArgs} is null (don't let this happen)
475   */
476  public static void checkState(
477      boolean expression,
478      @Nullable String errorMessageTemplate,
479      @Nullable Object... errorMessageArgs) {
480    if (!expression) {
481      throw new IllegalStateException(format(errorMessageTemplate, errorMessageArgs));
482    }
483  }
484
485  /**
486   * Ensures the truth of an expression involving the state of the calling instance, but not
487   * involving any parameters to the calling method.
488   *
489   * <p>See {@link #checkState(boolean, String, Object...)} for details.
490   */
491  public static void checkState(boolean b, @Nullable String errorMessageTemplate, char p1) {
492    if (!b) {
493      throw new IllegalStateException(format(errorMessageTemplate, p1));
494    }
495  }
496
497  /**
498   * Ensures the truth of an expression involving the state of the calling instance, but not
499   * involving any parameters to the calling method.
500   *
501   * <p>See {@link #checkState(boolean, String, Object...)} for details.
502   */
503  public static void checkState(boolean b, @Nullable String errorMessageTemplate, int p1) {
504    if (!b) {
505      throw new IllegalStateException(format(errorMessageTemplate, p1));
506    }
507  }
508
509  /**
510   * Ensures the truth of an expression involving the state of the calling instance, but not
511   * involving any parameters to the calling method.
512   *
513   * <p>See {@link #checkState(boolean, String, Object...)} for details.
514   */
515  public static void checkState(boolean b, @Nullable String errorMessageTemplate, long p1) {
516    if (!b) {
517      throw new IllegalStateException(format(errorMessageTemplate, p1));
518    }
519  }
520
521  /**
522   * Ensures the truth of an expression involving the state of the calling instance, but not
523   * involving any parameters to the calling method.
524   *
525   * <p>See {@link #checkState(boolean, String, Object...)} for details.
526   */
527  public static void checkState(
528      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1) {
529    if (!b) {
530      throw new IllegalStateException(format(errorMessageTemplate, p1));
531    }
532  }
533
534  /**
535   * Ensures the truth of an expression involving the state of the calling instance, but not
536   * involving any parameters to the calling method.
537   *
538   * <p>See {@link #checkState(boolean, String, Object...)} for details.
539   */
540  public static void checkState(
541      boolean b, @Nullable String errorMessageTemplate, char p1, char p2) {
542    if (!b) {
543      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
544    }
545  }
546
547  /**
548   * Ensures the truth of an expression involving the state of the calling instance, but not
549   * involving any parameters to the calling method.
550   *
551   * <p>See {@link #checkState(boolean, String, Object...)} for details.
552   */
553  public static void checkState(boolean b, @Nullable String errorMessageTemplate, char p1, int p2) {
554    if (!b) {
555      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
556    }
557  }
558
559  /**
560   * Ensures the truth of an expression involving the state of the calling instance, but not
561   * involving any parameters to the calling method.
562   *
563   * <p>See {@link #checkState(boolean, String, Object...)} for details.
564   */
565  public static void checkState(
566      boolean b, @Nullable String errorMessageTemplate, char p1, long p2) {
567    if (!b) {
568      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
569    }
570  }
571
572  /**
573   * Ensures the truth of an expression involving the state of the calling instance, but not
574   * involving any parameters to the calling method.
575   *
576   * <p>See {@link #checkState(boolean, String, Object...)} for details.
577   */
578  public static void checkState(
579      boolean b, @Nullable String errorMessageTemplate, char p1, @Nullable Object p2) {
580    if (!b) {
581      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
582    }
583  }
584
585  /**
586   * Ensures the truth of an expression involving the state of the calling instance, but not
587   * involving any parameters to the calling method.
588   *
589   * <p>See {@link #checkState(boolean, String, Object...)} for details.
590   */
591  public static void checkState(boolean b, @Nullable String errorMessageTemplate, int p1, char p2) {
592    if (!b) {
593      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
594    }
595  }
596
597  /**
598   * Ensures the truth of an expression involving the state of the calling instance, but not
599   * involving any parameters to the calling method.
600   *
601   * <p>See {@link #checkState(boolean, String, Object...)} for details.
602   */
603  public static void checkState(boolean b, @Nullable String errorMessageTemplate, int p1, int p2) {
604    if (!b) {
605      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
606    }
607  }
608
609  /**
610   * Ensures the truth of an expression involving the state of the calling instance, but not
611   * involving any parameters to the calling method.
612   *
613   * <p>See {@link #checkState(boolean, String, Object...)} for details.
614   */
615  public static void checkState(boolean b, @Nullable String errorMessageTemplate, int p1, long p2) {
616    if (!b) {
617      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
618    }
619  }
620
621  /**
622   * Ensures the truth of an expression involving the state of the calling instance, but not
623   * involving any parameters to the calling method.
624   *
625   * <p>See {@link #checkState(boolean, String, Object...)} for details.
626   */
627  public static void checkState(
628      boolean b, @Nullable String errorMessageTemplate, int p1, @Nullable Object p2) {
629    if (!b) {
630      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
631    }
632  }
633
634  /**
635   * Ensures the truth of an expression involving the state of the calling instance, but not
636   * involving any parameters to the calling method.
637   *
638   * <p>See {@link #checkState(boolean, String, Object...)} for details.
639   */
640  public static void checkState(
641      boolean b, @Nullable String errorMessageTemplate, long p1, char p2) {
642    if (!b) {
643      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
644    }
645  }
646
647  /**
648   * Ensures the truth of an expression involving the state of the calling instance, but not
649   * involving any parameters to the calling method.
650   *
651   * <p>See {@link #checkState(boolean, String, Object...)} for details.
652   */
653  public static void checkState(boolean b, @Nullable String errorMessageTemplate, long p1, int p2) {
654    if (!b) {
655      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
656    }
657  }
658
659  /**
660   * Ensures the truth of an expression involving the state of the calling instance, but not
661   * involving any parameters to the calling method.
662   *
663   * <p>See {@link #checkState(boolean, String, Object...)} for details.
664   */
665  public static void checkState(
666      boolean b, @Nullable String errorMessageTemplate, long p1, long p2) {
667    if (!b) {
668      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
669    }
670  }
671
672  /**
673   * Ensures the truth of an expression involving the state of the calling instance, but not
674   * involving any parameters to the calling method.
675   *
676   * <p>See {@link #checkState(boolean, String, Object...)} for details.
677   */
678  public static void checkState(
679      boolean b, @Nullable String errorMessageTemplate, long p1, @Nullable Object p2) {
680    if (!b) {
681      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
682    }
683  }
684
685  /**
686   * Ensures the truth of an expression involving the state of the calling instance, but not
687   * involving any parameters to the calling method.
688   *
689   * <p>See {@link #checkState(boolean, String, Object...)} for details.
690   */
691  public static void checkState(
692      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, char p2) {
693    if (!b) {
694      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
695    }
696  }
697
698  /**
699   * Ensures the truth of an expression involving the state of the calling instance, but not
700   * involving any parameters to the calling method.
701   *
702   * <p>See {@link #checkState(boolean, String, Object...)} for details.
703   */
704  public static void checkState(
705      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, int p2) {
706    if (!b) {
707      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
708    }
709  }
710
711  /**
712   * Ensures the truth of an expression involving the state of the calling instance, but not
713   * involving any parameters to the calling method.
714   *
715   * <p>See {@link #checkState(boolean, String, Object...)} for details.
716   */
717  public static void checkState(
718      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, long p2) {
719    if (!b) {
720      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
721    }
722  }
723
724  /**
725   * Ensures the truth of an expression involving the state of the calling instance, but not
726   * involving any parameters to the calling method.
727   *
728   * <p>See {@link #checkState(boolean, String, Object...)} for details.
729   */
730  public static void checkState(
731      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, @Nullable Object p2) {
732    if (!b) {
733      throw new IllegalStateException(format(errorMessageTemplate, p1, p2));
734    }
735  }
736
737  /**
738   * Ensures the truth of an expression involving the state of the calling instance, but not
739   * involving any parameters to the calling method.
740   *
741   * <p>See {@link #checkState(boolean, String, Object...)} for details.
742   */
743  public static void checkState(
744      boolean b,
745      @Nullable String errorMessageTemplate,
746      @Nullable Object p1,
747      @Nullable Object p2,
748      @Nullable Object p3) {
749    if (!b) {
750      throw new IllegalStateException(format(errorMessageTemplate, p1, p2, p3));
751    }
752  }
753
754  /**
755   * Ensures the truth of an expression involving the state of the calling instance, but not
756   * involving any parameters to the calling method.
757   *
758   * <p>See {@link #checkState(boolean, String, Object...)} for details.
759   */
760  public static void checkState(
761      boolean b,
762      @Nullable String errorMessageTemplate,
763      @Nullable Object p1,
764      @Nullable Object p2,
765      @Nullable Object p3,
766      @Nullable Object p4) {
767    if (!b) {
768      throw new IllegalStateException(format(errorMessageTemplate, p1, p2, p3, p4));
769    }
770  }
771
772  /**
773   * Ensures that an object reference passed as a parameter to the calling method is not null.
774   *
775   * @param reference an object reference
776   * @return the non-null reference that was validated
777   * @throws NullPointerException if {@code reference} is null
778   */
779  @CanIgnoreReturnValue
780  public static <T> T checkNotNull(T reference) {
781    if (reference == null) {
782      throw new NullPointerException();
783    }
784    return reference;
785  }
786
787  /**
788   * Ensures that an object reference passed as a parameter to the calling method is not null.
789   *
790   * @param reference an object reference
791   * @param errorMessage the exception message to use if the check fails; will be converted to a
792   *     string using {@link String#valueOf(Object)}
793   * @return the non-null reference that was validated
794   * @throws NullPointerException if {@code reference} is null
795   */
796  @CanIgnoreReturnValue
797  public static <T> T checkNotNull(T reference, @Nullable Object errorMessage) {
798    if (reference == null) {
799      throw new NullPointerException(String.valueOf(errorMessage));
800    }
801    return reference;
802  }
803
804  /**
805   * Ensures that an object reference passed as a parameter to the calling method is not null.
806   *
807   * @param reference an object reference
808   * @param errorMessageTemplate a template for the exception message should the check fail. The
809   *     message is formed by replacing each {@code %s} placeholder in the template with an
810   *     argument. These are matched by position - the first {@code %s} gets {@code
811   *     errorMessageArgs[0]}, etc. Unmatched arguments will be appended to the formatted message in
812   *     square braces. Unmatched placeholders will be left as-is.
813   * @param errorMessageArgs the arguments to be substituted into the message template. Arguments
814   *     are converted to strings using {@link String#valueOf(Object)}.
815   * @return the non-null reference that was validated
816   * @throws NullPointerException if {@code reference} is null
817   */
818  @CanIgnoreReturnValue
819  public static <T> T checkNotNull(
820      T reference, @Nullable String errorMessageTemplate, @Nullable Object... errorMessageArgs) {
821    if (reference == null) {
822      // If either of these parameters is null, the right thing happens anyway
823      throw new NullPointerException(format(errorMessageTemplate, errorMessageArgs));
824    }
825    return reference;
826  }
827
828  /**
829   * Ensures that an object reference passed as a parameter to the calling method is not null.
830   *
831   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
832   */
833  @CanIgnoreReturnValue
834  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, char p1) {
835    if (obj == null) {
836      throw new NullPointerException(format(errorMessageTemplate, p1));
837    }
838    return obj;
839  }
840
841  /**
842   * Ensures that an object reference passed as a parameter to the calling method is not null.
843   *
844   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
845   */
846  @CanIgnoreReturnValue
847  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, int p1) {
848    if (obj == null) {
849      throw new NullPointerException(format(errorMessageTemplate, p1));
850    }
851    return obj;
852  }
853
854  /**
855   * Ensures that an object reference passed as a parameter to the calling method is not null.
856   *
857   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
858   */
859  @CanIgnoreReturnValue
860  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, long p1) {
861    if (obj == null) {
862      throw new NullPointerException(format(errorMessageTemplate, p1));
863    }
864    return obj;
865  }
866
867  /**
868   * Ensures that an object reference passed as a parameter to the calling method is not null.
869   *
870   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
871   */
872  @CanIgnoreReturnValue
873  public static <T> T checkNotNull(
874      T obj, @Nullable String errorMessageTemplate, @Nullable Object p1) {
875    if (obj == null) {
876      throw new NullPointerException(format(errorMessageTemplate, p1));
877    }
878    return obj;
879  }
880
881  /**
882   * Ensures that an object reference passed as a parameter to the calling method is not null.
883   *
884   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
885   */
886  @CanIgnoreReturnValue
887  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, char p1, char p2) {
888    if (obj == null) {
889      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
890    }
891    return obj;
892  }
893
894  /**
895   * Ensures that an object reference passed as a parameter to the calling method is not null.
896   *
897   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
898   */
899  @CanIgnoreReturnValue
900  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, char p1, int p2) {
901    if (obj == null) {
902      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
903    }
904    return obj;
905  }
906
907  /**
908   * Ensures that an object reference passed as a parameter to the calling method is not null.
909   *
910   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
911   */
912  @CanIgnoreReturnValue
913  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, char p1, long p2) {
914    if (obj == null) {
915      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
916    }
917    return obj;
918  }
919
920  /**
921   * Ensures that an object reference passed as a parameter to the calling method is not null.
922   *
923   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
924   */
925  @CanIgnoreReturnValue
926  public static <T> T checkNotNull(
927      T obj, @Nullable String errorMessageTemplate, char p1, @Nullable Object p2) {
928    if (obj == null) {
929      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
930    }
931    return obj;
932  }
933
934  /**
935   * Ensures that an object reference passed as a parameter to the calling method is not null.
936   *
937   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
938   */
939  @CanIgnoreReturnValue
940  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, int p1, char p2) {
941    if (obj == null) {
942      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
943    }
944    return obj;
945  }
946
947  /**
948   * Ensures that an object reference passed as a parameter to the calling method is not null.
949   *
950   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
951   */
952  @CanIgnoreReturnValue
953  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, int p1, int p2) {
954    if (obj == null) {
955      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
956    }
957    return obj;
958  }
959
960  /**
961   * Ensures that an object reference passed as a parameter to the calling method is not null.
962   *
963   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
964   */
965  @CanIgnoreReturnValue
966  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, int p1, long p2) {
967    if (obj == null) {
968      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
969    }
970    return obj;
971  }
972
973  /**
974   * Ensures that an object reference passed as a parameter to the calling method is not null.
975   *
976   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
977   */
978  @CanIgnoreReturnValue
979  public static <T> T checkNotNull(
980      T obj, @Nullable String errorMessageTemplate, int p1, @Nullable Object p2) {
981    if (obj == null) {
982      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
983    }
984    return obj;
985  }
986
987  /**
988   * Ensures that an object reference passed as a parameter to the calling method is not null.
989   *
990   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
991   */
992  @CanIgnoreReturnValue
993  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, long p1, char p2) {
994    if (obj == null) {
995      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
996    }
997    return obj;
998  }
999
1000  /**
1001   * Ensures that an object reference passed as a parameter to the calling method is not null.
1002   *
1003   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
1004   */
1005  @CanIgnoreReturnValue
1006  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, long p1, int p2) {
1007    if (obj == null) {
1008      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
1009    }
1010    return obj;
1011  }
1012
1013  /**
1014   * Ensures that an object reference passed as a parameter to the calling method is not null.
1015   *
1016   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
1017   */
1018  @CanIgnoreReturnValue
1019  public static <T> T checkNotNull(T obj, @Nullable String errorMessageTemplate, long p1, long p2) {
1020    if (obj == null) {
1021      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
1022    }
1023    return obj;
1024  }
1025
1026  /**
1027   * Ensures that an object reference passed as a parameter to the calling method is not null.
1028   *
1029   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
1030   */
1031  @CanIgnoreReturnValue
1032  public static <T> T checkNotNull(
1033      T obj, @Nullable String errorMessageTemplate, long p1, @Nullable Object p2) {
1034    if (obj == null) {
1035      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
1036    }
1037    return obj;
1038  }
1039
1040  /**
1041   * Ensures that an object reference passed as a parameter to the calling method is not null.
1042   *
1043   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
1044   */
1045  @CanIgnoreReturnValue
1046  public static <T> T checkNotNull(
1047      T obj, @Nullable String errorMessageTemplate, @Nullable Object p1, char p2) {
1048    if (obj == null) {
1049      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
1050    }
1051    return obj;
1052  }
1053
1054  /**
1055   * Ensures that an object reference passed as a parameter to the calling method is not null.
1056   *
1057   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
1058   */
1059  @CanIgnoreReturnValue
1060  public static <T> T checkNotNull(
1061      T obj, @Nullable String errorMessageTemplate, @Nullable Object p1, int p2) {
1062    if (obj == null) {
1063      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
1064    }
1065    return obj;
1066  }
1067
1068  /**
1069   * Ensures that an object reference passed as a parameter to the calling method is not null.
1070   *
1071   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
1072   */
1073  @CanIgnoreReturnValue
1074  public static <T> T checkNotNull(
1075      T obj, @Nullable String errorMessageTemplate, @Nullable Object p1, long p2) {
1076    if (obj == null) {
1077      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
1078    }
1079    return obj;
1080  }
1081
1082  /**
1083   * Ensures that an object reference passed as a parameter to the calling method is not null.
1084   *
1085   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
1086   */
1087  @CanIgnoreReturnValue
1088  public static <T> T checkNotNull(
1089      T obj, @Nullable String errorMessageTemplate, @Nullable Object p1, @Nullable Object p2) {
1090    if (obj == null) {
1091      throw new NullPointerException(format(errorMessageTemplate, p1, p2));
1092    }
1093    return obj;
1094  }
1095
1096  /**
1097   * Ensures that an object reference passed as a parameter to the calling method is not null.
1098   *
1099   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
1100   */
1101  @CanIgnoreReturnValue
1102  public static <T> T checkNotNull(
1103      T obj,
1104      @Nullable String errorMessageTemplate,
1105      @Nullable Object p1,
1106      @Nullable Object p2,
1107      @Nullable Object p3) {
1108    if (obj == null) {
1109      throw new NullPointerException(format(errorMessageTemplate, p1, p2, p3));
1110    }
1111    return obj;
1112  }
1113
1114  /**
1115   * Ensures that an object reference passed as a parameter to the calling method is not null.
1116   *
1117   * <p>See {@link #checkNotNull(Object, String, Object...)} for details.
1118   */
1119  @CanIgnoreReturnValue
1120  public static <T> T checkNotNull(
1121      T obj,
1122      @Nullable String errorMessageTemplate,
1123      @Nullable Object p1,
1124      @Nullable Object p2,
1125      @Nullable Object p3,
1126      @Nullable Object p4) {
1127    if (obj == null) {
1128      throw new NullPointerException(format(errorMessageTemplate, p1, p2, p3, p4));
1129    }
1130    return obj;
1131  }
1132
1133  /*
1134   * All recent hotspots (as of 2009) *really* like to have the natural code
1135   *
1136   * if (guardExpression) {
1137   *    throw new BadException(messageExpression);
1138   * }
1139   *
1140   * refactored so that messageExpression is moved to a separate String-returning method.
1141   *
1142   * if (guardExpression) {
1143   *    throw new BadException(badMsg(...));
1144   * }
1145   *
1146   * The alternative natural refactorings into void or Exception-returning methods are much slower.
1147   * This is a big deal - we're talking factors of 2-8 in microbenchmarks, not just 10-20%. (This is
1148   * a hotspot optimizer bug, which should be fixed, but that's a separate, big project).
1149   *
1150   * The coding pattern above is heavily used in java.util, e.g. in ArrayList. There is a
1151   * RangeCheckMicroBenchmark in the JDK that was used to test this.
1152   *
1153   * But the methods in this class want to throw different exceptions, depending on the args, so it
1154   * appears that this pattern is not directly applicable. But we can use the ridiculous, devious
1155   * trick of throwing an exception in the middle of the construction of another exception. Hotspot
1156   * is fine with that.
1157   */
1158
1159  /**
1160   * Ensures that {@code index} specifies a valid <i>element</i> in an array, list or string of size
1161   * {@code size}. An element index may range from zero, inclusive, to {@code size}, exclusive.
1162   *
1163   * @param index a user-supplied index identifying an element of an array, list or string
1164   * @param size the size of that array, list or string
1165   * @return the value of {@code index}
1166   * @throws IndexOutOfBoundsException if {@code index} is negative or is not less than {@code size}
1167   * @throws IllegalArgumentException if {@code size} is negative
1168   */
1169  @CanIgnoreReturnValue
1170  public static int checkElementIndex(int index, int size) {
1171    return checkElementIndex(index, size, "index");
1172  }
1173
1174  /**
1175   * Ensures that {@code index} specifies a valid <i>element</i> in an array, list or string of size
1176   * {@code size}. An element index may range from zero, inclusive, to {@code size}, exclusive.
1177   *
1178   * @param index a user-supplied index identifying an element of an array, list or string
1179   * @param size the size of that array, list or string
1180   * @param desc the text to use to describe this index in an error message
1181   * @return the value of {@code index}
1182   * @throws IndexOutOfBoundsException if {@code index} is negative or is not less than {@code size}
1183   * @throws IllegalArgumentException if {@code size} is negative
1184   */
1185  @CanIgnoreReturnValue
1186  public static int checkElementIndex(int index, int size, @Nullable String desc) {
1187    // Carefully optimized for execution by hotspot (explanatory comment above)
1188    if (index < 0 || index >= size) {
1189      throw new IndexOutOfBoundsException(badElementIndex(index, size, desc));
1190    }
1191    return index;
1192  }
1193
1194  private static String badElementIndex(int index, int size, String desc) {
1195    if (index < 0) {
1196      return format("%s (%s) must not be negative", desc, index);
1197    } else if (size < 0) {
1198      throw new IllegalArgumentException("negative size: " + size);
1199    } else { // index >= size
1200      return format("%s (%s) must be less than size (%s)", desc, index, size);
1201    }
1202  }
1203
1204  /**
1205   * Ensures that {@code index} specifies a valid <i>position</i> in an array, list or string of
1206   * size {@code size}. A position index may range from zero to {@code size}, inclusive.
1207   *
1208   * @param index a user-supplied index identifying a position in an array, list or string
1209   * @param size the size of that array, list or string
1210   * @return the value of {@code index}
1211   * @throws IndexOutOfBoundsException if {@code index} is negative or is greater than {@code size}
1212   * @throws IllegalArgumentException if {@code size} is negative
1213   */
1214  @CanIgnoreReturnValue
1215  public static int checkPositionIndex(int index, int size) {
1216    return checkPositionIndex(index, size, "index");
1217  }
1218
1219  /**
1220   * Ensures that {@code index} specifies a valid <i>position</i> in an array, list or string of
1221   * size {@code size}. A position index may range from zero to {@code size}, inclusive.
1222   *
1223   * @param index a user-supplied index identifying a position in an array, list or string
1224   * @param size the size of that array, list or string
1225   * @param desc the text to use to describe this index in an error message
1226   * @return the value of {@code index}
1227   * @throws IndexOutOfBoundsException if {@code index} is negative or is greater than {@code size}
1228   * @throws IllegalArgumentException if {@code size} is negative
1229   */
1230  @CanIgnoreReturnValue
1231  public static int checkPositionIndex(int index, int size, @Nullable String desc) {
1232    // Carefully optimized for execution by hotspot (explanatory comment above)
1233    if (index < 0 || index > size) {
1234      throw new IndexOutOfBoundsException(badPositionIndex(index, size, desc));
1235    }
1236    return index;
1237  }
1238
1239  private static String badPositionIndex(int index, int size, String desc) {
1240    if (index < 0) {
1241      return format("%s (%s) must not be negative", desc, index);
1242    } else if (size < 0) {
1243      throw new IllegalArgumentException("negative size: " + size);
1244    } else { // index > size
1245      return format("%s (%s) must not be greater than size (%s)", desc, index, size);
1246    }
1247  }
1248
1249  /**
1250   * Ensures that {@code start} and {@code end} specify a valid <i>positions</i> in an array, list
1251   * or string of size {@code size}, and are in order. A position index may range from zero to
1252   * {@code size}, inclusive.
1253   *
1254   * @param start a user-supplied index identifying a starting position in an array, list or string
1255   * @param end a user-supplied index identifying a ending position in an array, list or string
1256   * @param size the size of that array, list or string
1257   * @throws IndexOutOfBoundsException if either index is negative or is greater than {@code size},
1258   *     or if {@code end} is less than {@code start}
1259   * @throws IllegalArgumentException if {@code size} is negative
1260   */
1261  public static void checkPositionIndexes(int start, int end, int size) {
1262    // Carefully optimized for execution by hotspot (explanatory comment above)
1263    if (start < 0 || end < start || end > size) {
1264      throw new IndexOutOfBoundsException(badPositionIndexes(start, end, size));
1265    }
1266  }
1267
1268  private static String badPositionIndexes(int start, int end, int size) {
1269    if (start < 0 || start > size) {
1270      return badPositionIndex(start, size, "start index");
1271    }
1272    if (end < 0 || end > size) {
1273      return badPositionIndex(end, size, "end index");
1274    }
1275    // end < start
1276    return format("end index (%s) must not be less than start index (%s)", end, start);
1277  }
1278
1279  /**
1280   * Substitutes each {@code %s} in {@code template} with an argument. These are matched by
1281   * position: the first {@code %s} gets {@code args[0]}, etc. If there are more arguments than
1282   * placeholders, the unmatched arguments will be appended to the end of the formatted message in
1283   * square braces.
1284   *
1285   * @param template a non-null string containing 0 or more {@code %s} placeholders.
1286   * @param args the arguments to be substituted into the message template. Arguments are converted
1287   *     to strings using {@link String#valueOf(Object)}. Arguments can be null.
1288   */
1289  // Note that this is somewhat-improperly used from Verify.java as well.
1290  static String format(String template, @Nullable Object... args) {
1291    template = String.valueOf(template); // null -> "null"
1292
1293    // start substituting the arguments into the '%s' placeholders
1294    StringBuilder builder = new StringBuilder(template.length() + 16 * args.length);
1295    int templateStart = 0;
1296    int i = 0;
1297    while (i < args.length) {
1298      int placeholderStart = template.indexOf("%s", templateStart);
1299      if (placeholderStart == -1) {
1300        break;
1301      }
1302      builder.append(template, templateStart, placeholderStart);
1303      builder.append(args[i++]);
1304      templateStart = placeholderStart + 2;
1305    }
1306    builder.append(template, templateStart, template.length());
1307
1308    // if we run out of placeholders, append the extra args in square braces
1309    if (i < args.length) {
1310      builder.append(" [");
1311      builder.append(args[i++]);
1312      while (i < args.length) {
1313        builder.append(", ");
1314        builder.append(args[i++]);
1315      }
1316      builder.append(']');
1317    }
1318
1319    return builder.toString();
1320  }
1321}