Example usage for java.util Random nextInt

Introduction

In this page you can find the example usage for java.util Random nextInt.

Prototype

public int nextInt(int bound) 

Source Link

Document

Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.

Usage

From source file:setiquest.renderer.Utils.java

/**
 * Get a random file from a directory.//from w w  w  .j av a 2  s.c  o m
 * @param dir the directory to search in.
 * @return a file name full path.
 */
public static String getRandomFile(String dir) {
    File directory = new File(dir);
    int count = 0;
    String randomFileName = "";

    if (directory.exists()) {
        File[] listFiles = directory.listFiles();
        int numFiles = listFiles.length;
        Random rand = new Random(System.currentTimeMillis());
        int index = rand.nextInt(numFiles - 1);
        randomFileName = listFiles[index].getAbsolutePath();

    }

    return randomFileName;
}

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From source file:com.datumbox.framework.common.utilities.PHPMethods.java

/**
 * Shuffles the values of any array in place.
 * /*from  w  w w  .ja va  2 s  .c  o m*/
 * @param <T>
 * @param array 
 */
public static <T> void shuffle(T[] array) {
    //Implementing Fisher-Yates shuffle
    T tmp;
    Random rnd = RandomGenerator.getThreadLocalRandom();
    for (int i = array.length - 1; i > 0; --i) {
        int index = rnd.nextInt(i + 1);

        tmp = array[index];
        array[index] = array[i];
        array[i] = tmp;
    }
}

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From source file:demo.enumj.EnumeratorDemo.java

private static void demoChoiceOf(String pre) {
    final Random rnd = new Random();
    final Enumerator<Integer> en = Enumerator.choiceOf(() -> rnd.nextInt(2), _123.iterator(),
            Enumerator.on(4, 5, 6, 7, 8));
    printLn(en, "Randomly chosen elements:", pre);
}

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From source file:com.impetus.ankush.common.utils.PasswordUtil.java

/**
 * Gets the random password./*from  w w  w .  j a  v a  2s.co m*/
 *
 * @param length the length
 * @param smallChars the small chars
 * @param capsChars the caps chars
 * @param digits the digits
 * @param specialChars the special chars
 * @return the random password
 */
private static String getRandomPassword(int length, char[] smallChars, char[] capsChars, char[] digits,
        char[] specialChars) {
    char[][] charsArrArr = { smallChars, capsChars, digits, specialChars };
    String password = null;
    final int charSetCategories = 4;

    StringBuilder passwordGenBuff = new StringBuilder();
    Random r = new Random();

    int arrIdx[] = new int[charSetCategories];
    for (int pos = 0; pos < charSetCategories; ++pos) {
        arrIdx[pos] = 0;
    }

    while (passwordGenBuff.length() < length) {
        int setIdx = r.nextInt(charSetCategories);
        char[] chArr = charsArrArr[setIdx];
        if ((chArr == null) || (chArr.length == 0)) {
            continue;
        } else {
            int generatedPasswordLength = passwordGenBuff.length();
            int untouchedSetCount = 0;

            if (generatedPasswordLength > 0) {
                for (int idx = 0; idx < charSetCategories; idx++) {
                    char[] currArr = charsArrArr[idx];
                    if ((currArr != null) && (currArr.length > 0)) {
                        if (arrIdx[idx] == 0) {
                            ++untouchedSetCount;
                        }
                    }
                }

                if ((untouchedSetCount >= (length - generatedPasswordLength)) && (arrIdx[setIdx] > 0)) {
                    continue;
                }
            }

            passwordGenBuff.append(RandomStringUtils.random(1, chArr));

            ++arrIdx[setIdx];
        }
    }

    password = passwordGenBuff.toString();

    if (r.nextInt() % 2 == 0) {
        password = StringUtils.reverse(password);
    }

    return passwordGenBuff.toString();
}

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From source file:hivemall.mix.server.MixServerTest.java

private static void invokeClient(String groupId, int serverPort) throws InterruptedException {
    PredictionModel model = new DenseModel(16777216, false);
    model.configureClock();/*from  www  . j a  v a  2  s . co  m*/
    MixClient client = null;
    try {
        client = new MixClient(MixEventName.average, groupId, "localhost:" + serverPort, false, 2, model);
        model.configureMix(client, false);

        final Random rand = new Random(43);
        for (int i = 0; i < 100000; i++) {
            Integer feature = Integer.valueOf(rand.nextInt(100));
            float weight = (float) rand.nextGaussian();
            model.set(feature, new WeightValue(weight));
        }

        waitForMixed(model, 48000L, 10000L);

        long numMixed = model.getNumMixed();
        Assert.assertTrue("number of mix events: " + numMixed, numMixed > 0);
    } finally {
        IOUtils.closeQuietly(client);
    }

}

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From source file:Main.java

public static void shuffleSubArray(int[] array, int subArrayLength, Random rand) {

    if (subArrayLength == 0)
        return;//from  w  w w.ja va  2s . c o m

    int subArrays = array.length / subArrayLength;

    for (int subArraysNum = 0; subArraysNum < subArrays; subArraysNum++) {

        int subArrayEndIndex = (subArraysNum + 1) * subArrayLength;
        int subArrayStartIndex = subArrayEndIndex - subArrayLength;

        for (int i = subArrayEndIndex; i > subArrayStartIndex + 1; i--) {
            int b = rand.nextInt(subArrayEndIndex - subArrayStartIndex) + subArrayStartIndex;
            if (b != i - 1) {
                int e = array[i - 1];
                array[i - 1] = array[b];
                array[b] = e;
            }
        }

    }

}

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From source file:com.wabacus.util.FileLockTools.java

public static Object lock(String lockfile, int waitsec, int maxtimes) {
    Object lockresource = lock(lockfile);
    Random random = new Random();
    int times = 0;
    while (lockresource == null) {
        if (times++ >= maxtimes) {
            log.debug("??" + lockfile + "?" + maxtimes + "?");
            break;
        }/*from  w w w.j a  v  a 2s .  c o  m*/
        try {
            Thread.sleep(random.nextInt(waitsec) * 1000);
        } catch (Exception e) {
            e.printStackTrace();
        }
        lockresource = lock(lockfile);
    }
    return lockresource;
}

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From source file:hivemall.mix.server.MixServerTest.java

private static void invokeClient01(String groupId, int serverPort, boolean denseModel, boolean cancelMix)
        throws InterruptedException {
    PredictionModel model = denseModel ? new DenseModel(100, false) : new SparseModel(100, false);
    model.configureClock();/*  w  w  w  . j  av a 2s  .  c o  m*/
    MixClient client = null;
    try {
        client = new MixClient(MixEventName.average, groupId, "localhost:" + serverPort, false, 3, model);
        model.configureMix(client, cancelMix);

        final Random rand = new Random(43);
        for (int i = 0; i < 1000000; i++) {
            Integer feature = Integer.valueOf(rand.nextInt(100));
            float weight = rand.nextFloat() >= 0.5f ? 1.f : 0.f;
            model.set(feature, new WeightValue(weight));
        }

        waitForMixed(model, 100000L, 10000L);

        long numMixed = model.getNumMixed();
        Assert.assertTrue("number of mix events: " + numMixed, numMixed > 0);

        for (int i = 0; i < 100; i++) {
            float w = model.getWeight(i);
            Assert.assertEquals(0.5f, w, 0.1f);
        }
    } finally {
        IOUtils.closeQuietly(client);
    }
}

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From source file:com.thejustdo.util.Utils.java

/**
 * Builds a random code for a new Dream Box.
 *
 * @param prefix What must be putted before the real code.
 * @param length How long must be the new number
 * @return The built code.//from   w  ww  .j a va  2s . co m
 */
public static String buildRandomCode(String prefix, int length) {
    // 1. Gatter the prefix size.
    int prefixL = prefix.length();
    int n = length - prefixL;
    // 2. Build the n digit code.
    String code = "";
    Random random = new Random();
    do {
        code += random.nextInt(10);
    } while (code.length() < n);
    return prefix + code;
}

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From source file:com.phoenixst.plexus.examples.RandomGraphFactory.java

/**
 *  Creates a random graph according to the Barabasi-Albert model.
 *
 *  <P>Start with <code>numInitialNodes</code> nodes.  At each
 *  step, add a new node which is connected to
 *  <code>numEdges</code> existing nodes, with preference given to
 *  nodes that are more highly connected.
 *///from w  ww . ja v a2 s  .  c  o m
public static Graph createBarabasiAlbert(int numInitialNodes, int numFinalNodes, int numEdges) {
    if (numEdges > numInitialNodes) {
        throw new IllegalArgumentException("Number of edges cannot be more than the number of initial nodes.");
    }
    Graph graph = new DefaultGraph(new EmptyGraph(numInitialNodes + 1));
    Random random = new Random();

    // Start out with numEdges randomly connected from the last
    // node to other nodes.
    Object tail = new Integer(numInitialNodes);
    for (int k = 0; k < numEdges; k++) {
        while (true) {
            Object head = new Integer(random.nextInt(numInitialNodes));
            Predicate traverserPred = TraverserPredicateFactory.createEqualsNode(head,
                    GraphUtils.ANY_DIRECTION_MASK);
            if (graph.getIncidentEdge(tail, traverserPred) == null) {
                graph.addEdge(null, tail, head, true);
                break;
            }
        }
    }

    // Now, do the rest of the work
    int totalDegree = numEdges * 2;
    for (int i = numInitialNodes + 1; i < numFinalNodes; i++, totalDegree += numEdges * 2) {
        tail = new Integer(i);
        graph.addNode(tail);
        for (int k = 0; k < numEdges; k++) {
            while (true) {
                int randomDegreeSum = random.nextInt(totalDegree);
                Object head = new Integer(0);
                int degreeSum = 0;
                for (int headIndex = 0; degreeSum < randomDegreeSum; headIndex++) {
                    head = new Integer(headIndex);
                    degreeSum += graph.degree(head);
                }
                Predicate traverserPred = TraverserPredicateFactory.createEqualsNode(head,
                        GraphUtils.ANY_DIRECTION_MASK);
                if (graph.getIncidentEdge(tail, traverserPred) == null) {
                    graph.addEdge(null, tail, head, true);
                    break;
                }
            }
        }
    }
    return graph;
}

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