gnu.trove
Class PrimeFinder
java.lang.Object
|
+--gnu.trove.PrimeFinder
- public final class PrimeFinder
- extends java.lang.Object
Used to keep hash table capacities prime numbers.
Not of interest for users; only for implementors of hashtables.
Choosing prime numbers as hash table capacities is a good idea
to keep them working fast, particularly under hash table
expansions.
However, JDK 1.2, JGL 3.1 and many other toolkits do nothing to
keep capacities prime. This class provides efficient means to
choose prime capacities.
Choosing a prime is O(log 300) (binary search in a list
of 300 ints). Memory requirements: 1 KB static memory.
- Version:
- 1.0, 09/24/99
- Author:
- wolfgang.hoschek@cern.ch
Field Summary |
static int |
largestPrime
The largest prime this class can generate; currently equal to
Integer.MAX_VALUE. |
Method Summary |
static int |
nextPrime(int desiredCapacity)
Returns a prime number which is >= desiredCapacity
and very close to desiredCapacity (within 11% if
desiredCapacity >= 1000 ). |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
largestPrime
public static final int largestPrime
- The largest prime this class can generate; currently equal to
Integer.MAX_VALUE.
- See Also:
- Constant Field Values
PrimeFinder
public PrimeFinder()
nextPrime
public static final int nextPrime(int desiredCapacity)
- Returns a prime number which is
>= desiredCapacity
and very close to desiredCapacity
(within 11% if
desiredCapacity >= 1000
).
- Parameters:
desiredCapacity
- the capacity desired by the user.
- Returns:
- the capacity which should be used for a hashtable.
GNU Trove is copyright © 2001-2003 Eric D. Friedman. All Rights Reserved.