Diff of /jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/random/RandomDataImpl.java
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--- jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/random/RandomDataImpl.java 2005/05/15 18:22:02 170242
+++ jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/random/RandomDataImpl.java 2005/05/15 18:23:35 170243
@@ -21,24 +21,28 @@ import java.security.MessageDigest;
import java.security.SecureRandom;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
-import java.util.Random;
import java.util.Collection;
/**
- * Implements the {@link RandomData} interface using
- * {@link java.util.Random} and {@link java.util.Random.SecureRandom} instances
- * to generate data.
+ * Implements the {@link RandomData} interface using a {@link RandomGenerator}
+ * instance to generate non-secure data and a
+ * {@link java.security.SecureRandom} instance to provide data for the
+ * <code>nextSecureXxx</code> methods. If no <code>RandomGenerator</code>
+ * is provided in the constructor, the default is to use a generator based on
+ * {@link java.util.Random}. To plug in a different implementation,
+ * either implement <code>RandomGenerator</code> directly or extend
+ * {@link AbstractRandomGenerator}.
* <p>
* Supports reseeding the underlying pseudo-random number generator (PRNG).
* The <code>SecurityProvider</code> and <code>Algorithm</code>
* used by the <code>SecureRandom</code> instance can also be reset.
* <p>
- * For details on the PRNGs, see {@link java.util.Random} and
- * {@link java.util.Random.SecureRandom}.
+ * For details on the default PRNGs, see {@link java.util.Random} and
+ * {@link java.security.SecureRandom}.
* <p>
* <strong>Usage Notes</strong>: <ul>
* <li>
- * Instance variables are used to maintain <code>Random</code> and
+ * Instance variables are used to maintain <code>RandomGenerator</code> and
* <code>SecureRandom</code> instances used in data generation. Therefore,
* to generate a random sequence of values or strings, you should use just
* <strong>one</strong> <code>RandomDataImpl</code> instance repeatedly.</li>
@@ -52,15 +56,16 @@ import java.util.Collection;
* it any easier to predict subsequent values.</li>
* <li>
* When a new <code>RandomDataImpl</code> is created, the underlying random
- * number generators are <strong>not</strong> intialized. The first call to a
- * data generation method, or to a <code>reSeed()</code> method instantiates
- * the appropriate generator. If you do not explicitly seed the generator, it
- * is by default seeded with the current time in milliseconds</li>
+ * number generators are <strong>not</strong> intialized. If you do not
+ * explicitly seed the default non-secure generator, it is seeded with the current time
+ * in milliseconds on first use. The same holds for the secure generator.
+ * If you provide a <code>RandomGenerator</code> to the constructor, however,
+ * this generator is not reseeded by the constructor nor is it reseeded on
+ * first use. </li>
* <li>
* The <code>reSeed</code> and <code>reSeedSecure</code> methods delegate
- * to the corresponding methods on the underlying <code>Random</code> and
- * <code>SecureRandom</code> instances. Therefore, the contracts of these
- * methods are as defined in the JDK documentation. In particular,
+ * to the corresponding methods on the underlying <code>RandomGenerator</code>
+ * and<code>SecureRandom</code> instances. Therefore,
* <code>reSeed(long)</code> fully resets the initial state of the non-secure
* random number generator (so that reseeding with a specific value always
* results in the same subsequent random sequence); whereas reSeedSecure(long)
@@ -79,7 +84,7 @@ public class RandomDataImpl implements R
static final long serialVersionUID = -626730818244969716L;
/** underlying random number generator */
- private Random rand = null;
+ private RandomGenerator rand = null;
/** underlying secure random number generator */
private SecureRandom secRand = null;
@@ -89,6 +94,17 @@ public class RandomDataImpl implements R
*/
public RandomDataImpl() {
}
+
+ /**
+ * Construct a RandomDataImpl using the supplied {@link RandomGenerator}
+ * as the source of (non-secure) random data.
+ *
+ * @param rand the source of (non-secure) random data
+ */
+ public RandomDataImpl(RandomGenerator rand) {
+ super();
+ this.rand = rand;
+ }
/**
* <strong>Algorithm Description:</strong> hex strings are generated
@@ -106,7 +122,7 @@ public class RandomDataImpl implements R
}
//Get a random number generator
- Random ran = getRan();
+ RandomGenerator ran = getRan();
//Initialize output buffer
StringBuffer outBuffer = new StringBuffer();
@@ -148,7 +164,7 @@ public class RandomDataImpl implements R
throw new IllegalArgumentException
("upper bound must be > lower bound");
}
- Random rand = getRan();
+ RandomGenerator rand = getRan();
return lower + (int) (rand.nextDouble() * (upper - lower + 1));
}
@@ -165,7 +181,7 @@ public class RandomDataImpl implements R
throw new IllegalArgumentException
("upper bound must be > lower bound");
}
- Random rand = getRan();
+ RandomGenerator rand = getRan();
return lower + (long) (rand.nextDouble() * (upper - lower + 1));
}
@@ -291,7 +307,7 @@ public class RandomDataImpl implements R
long n = 0;
double r = 1.0d;
double rnd = 1.0d;
- Random rand = getRan();
+ RandomGenerator rand = getRan();
while (n < 1000 * mean) {
rnd = rand.nextDouble();
r = r * rnd;
@@ -317,7 +333,7 @@ public class RandomDataImpl implements R
if (sigma <= 0) {
throw new IllegalArgumentException("Gaussian std dev must be > 0");
}
- Random rand = getRan();
+ RandomGenerator rand = getRan();
return sigma * rand.nextGaussian() + mu;
}
@@ -338,7 +354,7 @@ public class RandomDataImpl implements R
throw new IllegalArgumentException
("Exponential mean must be >= 0");
}
- Random rand = getRan();
+ RandomGenerator rand = getRan();
double unif = rand.nextDouble();
while (unif == 0.0d) {
unif = rand.nextDouble();
@@ -352,18 +368,19 @@ public class RandomDataImpl implements R
* random double if Random.nextDouble() returns 0).
* This is necessary to provide a symmetric output interval
* (both endpoints excluded).
+ *
* @param lower the lower bound.
* @param upper the upper bound.
- * @return the random value.
+ * @return a uniformly distributed random value from the interval (lower, upper)
*/
public double nextUniform(double lower, double upper) {
if (lower >= upper) {
throw new IllegalArgumentException
("lower bound must be <= upper bound");
}
- Random rand = getRan();
+ RandomGenerator rand = getRan();
- // insure nextDouble() isn't 0.0
+ // ensure nextDouble() isn't 0.0
double u = rand.nextDouble();
while(u <= 0.0){
u = rand.nextDouble();
@@ -373,26 +390,27 @@ public class RandomDataImpl implements R
}
/**
- * Returns the static Random used to generate random data.
+ * Returns the RandomGenerator used to generate non-secure
+ * random data.
* <p>
- * Creates and initializes if null.
+ * Creates and initializes a default generator if null.
*
- * @return the static Random used to generate random data
+ * @return the Random used to generate random data
*/
- private Random getRan() {
+ private RandomGenerator getRan() {
if (rand == null) {
- rand = new Random();
+ rand = new JDKRandomGenerator();
rand.setSeed(System.currentTimeMillis());
}
return rand;
}
/**
- * Returns the static SecureRandom used to generate secure random data.
+ * Returns the SecureRandom used to generate secure random data.
* <p>
* Creates and initializes if null.
*
- * @return the static SecureRandom used to generate secure random data
+ * @return the SecureRandom used to generate secure random data
*/
private SecureRandom getSecRan() {
if (secRand == null) {
@@ -411,7 +429,7 @@ public class RandomDataImpl implements R
*/
public void reSeed(long seed) {
if (rand == null) {
- rand = new Random();
+ rand = new JDKRandomGenerator();
}
rand.setSeed(seed);
}
@@ -449,7 +467,7 @@ public class RandomDataImpl implements R
*/
public void reSeed() {
if (rand == null) {
- rand = new Random();
+ rand = new JDKRandomGenerator();
}
rand.setSeed(System.currentTimeMillis());
}
@@ -574,5 +592,4 @@ public class RandomDataImpl implements R
}
return natural;
}
-
-}
\ No newline at end of file
+}
