Package tripleplay.util

Class Randoms

java.lang.Object
tripleplay.util.Randoms
public class Randoms extends Object
Provides utility routines to simplify obtaining randomized values.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    getBoolean()
    Returns true or false with approximately even probability.
    boolean
    getChance(int n)
    Returns true approximately one in n times.
    float
    getFloat(float high)
    Returns a pseudorandom, uniformly distributed float value between 0.0 (inclusive) and the high (exclusive).
    float
    getInRange(float low, float high)
    Returns a pseudorandom, uniformly distributed float value between low (inclusive) and high (exclusive).
    int
    getInRange(int low, int high)
    Returns a pseudorandom, uniformly distributed int value between low (inclusive) and high (exclusive).
    int
    getInt(int high)
    Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and high (exclusive).
    float
    getNormal(float mean, float dev)
    Returns a pseudorandom, normally distributed float value around the mean with the standard deviation dev.
    boolean
    getProbability(float p)
    Has a probability p of returning true.
    <T> T
    pick(Iterable<? extends T> iterable, T ifEmpty)
    Pick a random element from the specified Iterable, or return ifEmpty if it is empty.
    <T> T
    pick(Iterator<? extends T> iterator, T ifEmpty)
    Pick a random element from the specified Iterator, or return ifEmpty if it is empty.
    <T> T
    pick(Map<? extends T,? extends Number> weightMap, T ifEmpty)
    Pick a random key from the specified mapping of weight values, or return ifEmpty if no mapping has a weight greater than 0.
    <T> T
    pluck(Iterable<? extends T> iterable, T ifEmpty)
    Pluck (remove) a random element from the specified Iterable, or return ifEmpty if it is empty.
    <T> void
    shuffle(List<T> list)
    Shuffle the specified list using our Random.
    static Randoms
    with(Random rand)
    A factory to create a new Randoms object.

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Method Details

    • with

      public static Randoms with(Random rand)
      A factory to create a new Randoms object.

    • getInt

      public int getInt(int high)
      Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and high (exclusive).
      Parameters:
      high - the high value limiting the random number sought.
      Throws:
      IllegalArgumentException - if high is not positive.

    • getInRange

      public int getInRange(int low, int high)
      Returns a pseudorandom, uniformly distributed int value between low (inclusive) and high (exclusive).
      Throws:
      IllegalArgumentException - if high - low is not positive.

    • getFloat

      public float getFloat(float high)
      Returns a pseudorandom, uniformly distributed float value between 0.0 (inclusive) and the high (exclusive).
      Parameters:
      high - the high value limiting the random number sought.

    • getInRange

      public float getInRange(float low, float high)
      Returns a pseudorandom, uniformly distributed float value between low (inclusive) and high (exclusive).

    • getChance

      public boolean getChance(int n)
      Returns true approximately one in n times.
      Throws:
      IllegalArgumentException - if n is not positive.

    • getProbability

      public boolean getProbability(float p)
      Has a probability p of returning true.

    • getBoolean

      public boolean getBoolean()
      Returns true or false with approximately even probability.

    • getNormal

      public float getNormal(float mean, float dev)
      Returns a pseudorandom, normally distributed float value around the mean with the standard deviation dev.

    • shuffle

      public <T> void shuffle(List<T> list)
      Shuffle the specified list using our Random.

    • pick

      public <T> T pick(Iterator<? extends T> iterator, T ifEmpty)
      Pick a random element from the specified Iterator, or return ifEmpty if it is empty.

      Implementation note: because the total size of the Iterator is not known, the random number generator is queried after the second element and every element thereafter.

      Throws:
      NullPointerException - if the iterator is null.

    • pick

      public <T> T pick(Iterable<? extends T> iterable, T ifEmpty)
      Pick a random element from the specified Iterable, or return ifEmpty if it is empty.

      Implementation note: optimized implementations are used if the Iterable is a List or Collection. Otherwise, it behaves as if calling pick(Iterator, Object) with the Iterable's Iterator.

      Throws:
      NullPointerException - if the iterable is null.

    • pick

      public <T> T pick(Map<? extends T,? extends Number> weightMap, T ifEmpty)
      Pick a random key from the specified mapping of weight values, or return ifEmpty if no mapping has a weight greater than 0. Each weight value is evaluated as a double.

      Implementation note: a random number is generated for every entry with a non-zero weight after the first such entry.

      Throws:
      NullPointerException - if the map is null.
      IllegalArgumentException - if any weight is less than 0.

    • pluck

      public <T> T pluck(Iterable<? extends T> iterable, T ifEmpty)
      Pluck (remove) a random element from the specified Iterable, or return ifEmpty if it is empty.

      Implementation note: optimized implementations are used if the Iterable is a List or Collection. Otherwise, two Iterators are created from the Iterable and a random number is generated after the second element and all beyond.

      Throws:
      NullPointerException - if the iterable is null.
      UnsupportedOperationException - if the iterable is unmodifiable or its Iterator does not support Iterator.remove().