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:RandNum.java

public static void main(String[] args) {
    int num;//  w w w  .  j  a  v  a  2 s.  c o  m
    int[] dist = new int[10]; // Storage for distribution

    // Generate 10000 random numbers using Math.random()
    for (int x = 0; x < 10000; x++) {
        num = (int) (Math.floor(Math.random() * 10));
        dist[num]++;
    }
    // Display distribution of random integers in the range
    // 0 to 9
    System.out.println("Distribution using Math.random() ");
    for (int k = 0; k < 10; k++)
        System.out.print(k + "\t");
    // Display results
    for (int y = 0; y < 10; y++) {
        System.out.print(dist[y] + "\t");
    }
    System.out.println();
}

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From source file:AnimationTester.java

public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    ArrayComponent panel = new ArrayComponent();
    frame.add(panel, BorderLayout.CENTER);

    frame.setSize(800, 300);//w  w  w .j  ava 2  s.  co m
    frame.setVisible(true);

    Double[] values = new Double[100];
    for (int i = 0; i < values.length; i++)
        values[i] = Math.random() * panel.getHeight();

    final Sorter sorter = new Sorter(values, panel);

    Thread sorterThread = new Thread(sorter);
    sorterThread.start();
}

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From source file:Main.java

public static void main(String[] args) {
    int a = 10;//from  ww w  . ja  v  a 2  s.  c om
    int b = -50;
    int c = 3;
    double x = 25.0;
    double y = 3.0;
    double z = 4.0;

    System.out.println("abs(b)     = " + Math.abs(b));
    System.out.println("cbrt(x)   = " + Math.cbrt(x));
    System.out.println("exp(y)     = " + Math.exp(z));
    System.out.println("hypot(y, z)= " + Math.hypot(y, z));

    System.out.println("log(y)    = " + Math.log(y));
    System.out.println("log10(y)  = " + Math.log10(y));
    System.out.println("max(a, b) = " + Math.max(a, b));
    System.out.println("min(a, b) = " + Math.min(a, b));
    System.out.println("pow(a, c) = " + Math.pow(a, c));
    System.out.println("random()  = " + Math.random());
    System.out.println("signum(b) = " + Math.signum(b));
    System.out.println("sqrt(x)   = " + Math.sqrt(y));
}

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From source file:mase.deprecated.FastMathTest.java

public static void main(String[] args) {
    double MIN = -10;
    double MAX = 10;
    int N = 10000;
    DescriptiveStatistics diff = new DescriptiveStatistics();
    DescriptiveStatistics diffJava = new DescriptiveStatistics();
    long tFast = 0, tNormal = 0, tBounded = 0, tJava = 0;
    for (int i = 0; i < N; i++) {
        double x = Math.random() * (MAX - MIN) + MIN;
        long t = System.nanoTime();
        double v1 = (1.0 / (1.0 + FastMath.expQuick(-1 * x)));
        tFast += System.nanoTime() - t;
        t = System.nanoTime();/* ww w  . ja  va2s.  com*/
        double v2 = (1.0 / (1.0 + FastMath.exp(-1 * x)));
        tNormal += System.nanoTime() - t;
        t = System.nanoTime();
        double v3 = (1.0 / (1.0 + BoundMath.exp(-1 * x)));
        tBounded += System.nanoTime() - t;
        t = System.nanoTime();
        double v4 = (1.0 / (1.0 + Math.exp(-1 * x)));
        tJava += System.nanoTime() - t;
        diff.addValue(Math.abs(v1 - v2));
        diffJava.addValue(Math.abs(v3 - v1));
    }

    System.out.println("MAX: " + diff.getMax());
    System.out.println("MEAN: " + diff.getMean());
    System.out.println("MAX JAVA: " + diffJava.getMax());
    System.out.println("MEAN JAVA: " + diffJava.getMean());

    System.out.println("Fast: " + tFast);
    System.out.println("Normal: " + tNormal);
    System.out.println("Bounded: " + tBounded);
    System.out.println("Java: " + tJava);
}

---

From source file:MainClass.java

public static void main(String[] args) throws Exception {
    File aFile = new File("C:/test.bin");
    RandomAccessFile ioFile = new RandomAccessFile(aFile, " rw");

    FileChannel ioChannel = ioFile.getChannel();
    final int PRIMESREQUIRED = 10;
    long[] primes = new long[PRIMESREQUIRED];

    int index = 0;
    final long REPLACEMENT = 999999L;

    final int PRIMECOUNT = (int) ioChannel.size() / 8;
    MappedByteBuffer buf = ioChannel.map(FileChannel.MapMode.READ_WRITE, 0L, ioChannel.size()).load();
    ioChannel.close();/*from w w  w. j  av a 2 s.  com*/

    for (int i = 0; i < PRIMESREQUIRED; i++) {
        index = 8 * (int) (PRIMECOUNT * Math.random());
        primes[i] = buf.getLong(index);
        buf.putLong(index, REPLACEMENT);
    }

    for (long prime : primes) {
        System.out.printf("%12d", prime);
    }
    ioFile.close();
}

---

From source file:MainClass.java

public static void main(String[] args) throws Exception {
    createFile();/*from www  .  j  ava 2  s .c om*/

    File aFile = new File("C:/primes.bin");
    FileInputStream inFile = new FileInputStream(aFile);

    FileChannel inChannel = inFile.getChannel();

    final int PRIMESREQUIRED = 10;
    ByteBuffer buf = ByteBuffer.allocate(8 * PRIMESREQUIRED);

    long[] primes = new long[PRIMESREQUIRED];
    int index = 0; // Position for a prime in the file

    // Count of primes in the file
    final int PRIMECOUNT = (int) inChannel.size() / 8;

    // Read the number of random primes required
    for (int i = 0; i < PRIMESREQUIRED; i++) {
        index = 8 * (int) (PRIMECOUNT * Math.random());
        inChannel.read(buf, index); // Read the value
        buf.flip();
        primes[i] = buf.getLong(); // Save it in the array
        buf.clear();
    }

    for (long prime : primes) {
        System.out.printf("%12d", prime);
    }
    inFile.close(); // Close the file and the channel

}

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From source file:Wake.java

public static void main(String args[]) {
    Wake queue = new Wake();
    Runnable r = new RunThis(queue);
    Thread t;//from w ww  . j ava 2s .  co  m
    for (int i = 0; i < 10; i++) {
        t = new Thread(r);
        t.start();
    }

    for (int i = 0; i < 11; i++) {
        try {
            Thread.sleep((long) (Math.random() * 1000));
        } catch (InterruptedException e) {
        }
        System.out.println("About to wake one thread");
        queue.wakeOne();
    }
}

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From source file:MainClass.java

public static void main(String[] args) throws Exception {
    Document document = new Document(PageSize.A4.rotate());
    PdfWriter.getInstance(document, new FileOutputStream("2.pdf"));
    document.open();/*from  ww  w . j av  a 2  s .c o  m*/
    PdfPTable datatable = new PdfPTable(10);
    int headerwidths[] = { 10, 24, 12, 12, 7, 7, 7, 7, 7, 7 };
    datatable.setWidths(headerwidths);
    datatable.setWidthPercentage(100);
    datatable.getDefaultCell().setPadding(5);

    datatable.setHeaderRows(2);

    datatable.getDefaultCell().setBorderWidth(1);
    for (int i = 1; i < 30; i++) {
        datatable.getDefaultCell().setHorizontalAlignment(Element.ALIGN_LEFT);
        datatable.addCell("myUserId");
        datatable.addCell("long long name");
        datatable.addCell("No Name Company");
        datatable.addCell("D" + i);
        datatable.getDefaultCell().setHorizontalAlignment(Element.ALIGN_CENTER);
        for (int j = 0; j < 6; j++)
            datatable.addCell(Math.random() > .5 ? "Yes" : "No");
    }
    datatable.setSplitLate(false);
    document.add(datatable);

    document.close();
}

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From source file:SharedDataSample.java

public static void main(String args[]) {
    final String labels[] = { "A", "B", "C", "D", "E", "F", "G", "H", "I", "J" };
    final DefaultComboBoxModel model = new DefaultComboBoxModel(labels);

    JFrame frame = new JFrame("Shared Data");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container contentPane = frame.getContentPane();

    JPanel panel = new JPanel();
    JComboBox comboBox1 = new JComboBox(model);
    comboBox1.setMaximumRowCount(5);// w w w  .  j a  v  a2  s.co  m
    comboBox1.setEditable(true);

    JComboBox comboBox2 = new JComboBox(model);
    comboBox2.setMaximumRowCount(5);
    comboBox2.setEditable(true);
    panel.add(comboBox1);
    panel.add(comboBox2);
    contentPane.add(panel, BorderLayout.NORTH);

    JList jlist = new JList(model);
    JScrollPane scrollPane = new JScrollPane(jlist);
    contentPane.add(scrollPane, BorderLayout.CENTER);

    JButton button = new JButton("Add");
    contentPane.add(button, BorderLayout.SOUTH);
    ActionListener actionListener = new ActionListener() {
        public void actionPerformed(ActionEvent actionEvent) {
            int index = (int) (Math.random() * labels.length);
            model.addElement(labels[index]);
        }
    };
    button.addActionListener(actionListener);

    frame.setSize(300, 200);
    frame.setVisible(true);
}

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From source file:LotteryDrawing.java

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);

    System.out.print("How many numbers do you need to draw? ");
    int k = in.nextInt();

    System.out.print("What is the highest number you can draw? ");
    int n = in.nextInt();

    // fill an array with numbers 1 2 3 . . . n
    int[] numbers = new int[n];
    for (int i = 0; i < numbers.length; i++)
        numbers[i] = i + 1;//from  w ww. j  a va  2  s. com

    // draw k numbers and put them into a second array
    int[] result = new int[k];
    for (int i = 0; i < result.length; i++) {
        // make a random index between 0 and n - 1
        int r = (int) (Math.random() * n);

        // pick the element at the random location
        result[i] = numbers[r];

        // move the last element into the random location
        numbers[r] = numbers[n - 1];
        n--;
    }

    // print the sorted array
    Arrays.sort(result);
    System.out.println("Bet the following combination. It'll make you rich!");
    for (int r : result)
        System.out.println(r);
}

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