Example usage for java.lang Math random

Introduction

In this page you can find the example usage for java.lang Math random.

Prototype

public static double random()

Source Link

Document

Returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0 .

Usage

From source file:Main.java

public static String getRandomMixString(int length) {
    StringBuilder builder = new StringBuilder();
    for (int i = 0; i < length; i++) {
        int randomInt = (int) (Math.random() * 10);
        if ((randomInt % 2) == 0) {
            char c = (char) (randomInt + 97);
            builder.append(c);//from   w  w w  .j  av a2s .co m
            continue;
        }
        builder.append(String.valueOf(randomInt));
    }

    return builder.toString();

}

From source file:alluxio.cli.JournalCrashTest.java

/**
 * Runs the crash test.//  w ww  .j a v a2  s  . c o m
 *
 * @param args no arguments
 */
public static void main(String[] args) {
    // Parse the input args.
    if (!parseInputArgs(args)) {
        System.exit(EXIT_FAILED);
    }

    System.out.println("Stop the current Alluxio cluster...");
    stopCluster();

    // Set NO_STORE and NO_PERSIST so that this test can work without AlluxioWorker.
    sCreateFileOptions = CreateFileOptions.defaults().setWriteType(WriteType.NONE);
    // Set the max retry to avoid long pending for client disconnect.
    if (System.getProperty(PropertyKey.USER_RPC_RETRY_MAX_NUM_RETRY.toString()) == null) {
        System.setProperty(PropertyKey.USER_RPC_RETRY_MAX_NUM_RETRY.toString(), "10");
    }

    System.out.println("Start Journal Crash Test...");
    long startTimeMs = System.currentTimeMillis();
    boolean ret = true;
    startMaster();

    int rounds = 0;
    while (System.currentTimeMillis() - startTimeMs < sTotalTimeMs) {
        rounds++;
        long aliveTimeMs = (long) (Math.random() * sMaxAliveTimeMs) + 100;
        LOG.info("Round {}: Planning Master Alive Time {}ms.", rounds, aliveTimeMs);

        System.out.println("Round " + rounds + " : Launch Clients...");
        sFileSystem = FileSystem.Factory.get();
        try {
            sFileSystem.delete(new AlluxioURI(sTestDir));
        } catch (Exception e) {
            // Test Directory not exist
        }

        // Launch all the client threads.
        setupClientThreads();
        for (Thread thread : sClientThreadList) {
            thread.start();
        }

        CommonUtils.sleepMs(LOG, aliveTimeMs);
        System.out.println("Round " + rounds + " : Crash Master...");
        killMaster();
        for (ClientThread clientThread : sClientThreadList) {
            clientThread.setIsStopped(true);
        }
        for (Thread thread : sClientThreadList) {
            try {
                thread.join();
            } catch (InterruptedException e) {
                LOG.error("Error when waiting thread", e);
            }
        }

        System.out.println("Round " + rounds + " : Check Status...");
        startMaster();
        boolean checkSuccess = false;
        try {
            checkSuccess = checkStatus();
        } catch (Exception e) {
            LOG.error("Failed to check status", e);
        }
        CliUtils.printPassInfo(checkSuccess);
        ret &= checkSuccess;
    }

    stopCluster();
    System.exit(ret ? EXIT_SUCCESS : EXIT_FAILED);
}

From source file:Main.java

public static String randomAlphaNumeric(int length) {
    StringBuffer buffer = new StringBuffer();
    String characters = "abcdefghijklmnopqrstuvwxyz0123456789";
    int charactersLength = characters.length();
    for (int i = 0; i < length; i++) {
        double index = Math.random() * charactersLength;
        buffer.append(characters.charAt((int) index));
    }//from  ww  w  . j  ava  2  s  .c o m
    return buffer.toString();
}

From source file:Main.java

public static int GetRandomIndex(int min, int max) {
    return (int) (Math.random() * (max - min + 1)) + min;
}

From source file:Main.java

/**
 * chooses a random color from array.xml
 *//*from w  ww . j  a  v  a2  s  .  c  om*/
public static int getRandomMaterialColor(Context context, String typeColor) {
    int returnColor = Color.GRAY;
    int arrayId = context.getResources().getIdentifier("mdcolor_" + typeColor, "array",
            context.getPackageName());

    if (arrayId != 0) {
        TypedArray colors = context.getResources().obtainTypedArray(arrayId);
        int index = (int) (Math.random() * colors.length());
        returnColor = colors.getColor(index, Color.GRAY);
        colors.recycle();
    }
    return returnColor;
}

From source file:Main.java

/**
 * Get a random number within a given range;
 *//*from  www  .  j  a  v a2s.co m*/
public static int getRandomInt(int min, int max) throws Exception {

    int ret;
    int range = max - min;

    ret = (int) (Math.random() * min) + range;

    Log.i(TAG, String.format("Generate an integer value between %d and %d: %d", min, max, ret));

    return ret;
}

From source file:alluxio.examples.JournalCrashTest.java

/**
 * Runs the crash test.//  w  w w  .  ja v a  2 s  .  co m
 *
 * Usage:
 * {@code java -cp
 * alluxio-<ALLUXIO-VERSION>-jar-with-dependencies.jar alluxio.examples.JournalCrashTest}
 *
 * @param args no arguments
 */
public static void main(String[] args) {
    // Parse the input args.
    if (!parseInputArgs(args)) {
        System.exit(EXIT_FAILED);
    }

    System.out.println("Stop the current Alluxio cluster...");
    stopCluster();

    // Set NO_STORE and NO_PERSIST so that this test can work without AlluxioWorker.
    sCreateFileOptions = CreateFileOptions.defaults().setWriteType(WriteType.NONE);
    // Set the max retry to avoid long pending for client disconnect.
    if (System.getProperty(Constants.MASTER_RETRY_COUNT) == null) {
        System.setProperty(Constants.MASTER_RETRY_COUNT, "10");
    }

    System.out.println("Start Journal Crash Test...");
    long startTimeMs = System.currentTimeMillis();
    boolean ret = true;
    startMaster();

    int rounds = 0;
    while (System.currentTimeMillis() - startTimeMs < sTotalTimeMs) {
        rounds++;
        long aliveTimeMs = (long) (Math.random() * sMaxAliveTimeMs) + 100;
        LOG.info("Round {}: Planning Master Alive Time {}ms.", rounds, aliveTimeMs);

        System.out.println("Round " + rounds + " : Launch Clients...");
        sFileSystem = FileSystem.Factory.get();
        try {
            sFileSystem.delete(new AlluxioURI(sTestDir));
        } catch (Exception e) {
            // Test Directory not exist
        }

        // Launch all the client threads.
        setupClientThreads();
        for (Thread thread : sClientThreadList) {
            thread.start();
        }

        CommonUtils.sleepMs(LOG, aliveTimeMs);
        System.out.println("Round " + rounds + " : Crash Master...");
        killMaster();
        for (ClientThread clientThread : sClientThreadList) {
            clientThread.setIsStopped(true);
        }
        for (Thread thread : sClientThreadList) {
            try {
                thread.join();
            } catch (InterruptedException e) {
                LOG.error("Error when waiting thread", e);
            }
        }

        System.out.println("Round " + rounds + " : Check Status...");
        startMaster();
        boolean checkSuccess = false;
        try {
            checkSuccess = checkStatus();
        } catch (Exception e) {
            LOG.error("Failed to check status", e);
        }
        Utils.printPassInfo(checkSuccess);
        ret &= checkSuccess;
    }

    stopCluster();
    System.exit(ret ? EXIT_SUCCESS : EXIT_FAILED);
}

From source file:Main.java

public static float rnd(final float min, final float max) {
    float fRandNum = (float) Math.random();
    return min + (max - min) * fRandNum;
}

From source file:Main.java

public static void getTop(double[] array, ArrayList<Integer> rankList, int i) {
    int index = 0;
    HashSet<Integer> scanned = new HashSet<Integer>();
    double max = Double.MIN_VALUE;
    for (int m = 0; m < i && m < array.length; m++) {
        max = Double.MIN_VALUE;// w  ww  .j  ava2  s  . c  o m
        for (int no = 0; no < array.length; no++) {
            if (!scanned.contains(no)) {
                if (array[no] > max) {
                    index = no;
                    max = array[no];
                } else if (array[no] == max && Math.random() > 0.5) {
                    index = no;
                    max = array[no];
                }
            }
        }
        if (!scanned.contains(index)) {
            scanned.add(index);
            rankList.add(index);
        }
        //System.out.println(m + "\t" + index);
    }
}

From source file:Main.java

public static <T> T random(List<T> list) {
    return list.get((int) Math.floor(Math.random() * list.size()));
}