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*/ |
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package jsr166y; |
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import java.util.*; |
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import java.util.Random; |
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/** |
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* A random number generator with the same properties as class {@link |
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* Random} but isolated to the current Thread. Like the global |
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* generator used by the {@link java.lang.Math} class, a |
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* ThreadLocalRandom is initialized with an internally generated seed |
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* that may not otherwise be modified. When applicable, use of |
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* ThreadLocalRandom rather than shared Random objects in concurrent |
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* programs will typically encounter much less overhead and |
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* contention. ThreadLocalRandoms are particularly appropriate when |
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* multiple tasks (for example, each a {@link ForkJoinTask}), use |
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* random numbers in parallel in thread pools. |
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* A random number generator isolated to the current thread. Like the |
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* global {@link java.util.Random} generator used by the {@link |
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* java.lang.Math} class, a {@code ThreadLocalRandom} is initialized |
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* with an internally generated seed that may not otherwise be |
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* modified. When applicable, use of {@code ThreadLocalRandom} rather |
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* than shared {@code Random} objects in concurrent programs will |
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* typically encounter much less overhead and contention. Use of |
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* {@code ThreadLocalRandom} is particularly appropriate when multiple |
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* tasks (for example, each a {@link ForkJoinTask}) use random numbers |
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* in parallel in thread pools. |
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* |
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* <p>Usages of this class should typically be of the form: |
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* {@code ThreadLocalRandom.current().nextX(...)} (where |
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* {@code X} is {@code Int}, {@code Long}, etc). |
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* When all usages are of this form, it is never possible to |
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* accidently share ThreadLocalRandoms across multiple threads. |
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* accidently share a {@code ThreadLocalRandom} across multiple threads. |
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* |
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* <p>This class also provides additional commonly used bounded random |
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* generation methods. |
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} |
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/** |
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* Returns the current Thread's ThreadLocalRandom. |
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* Returns the current thread's {@code ThreadLocalRandom}. |
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* |
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* @return the current Thread's ThreadLocalRandom |
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* @return the current thread's {@code ThreadLocalRandom} |
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*/ |
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public static ThreadLocalRandom current() { |
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return localRandom.get(); |
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} |
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/** |
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* Throws UnsupportedOperationException. Setting seeds in this |
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* generator is unsupported. |
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* Throws {@code UnsupportedOperationException}. Setting seeds in |
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* this generator is not supported. |
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* |
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* @throws UnsupportedOperationException always |
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*/ |
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return nextDouble() * (bound - least) + least; |
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} |
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+ |
private static final long serialVersionUID = -5851777807851030925L; |
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} |
