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Kryo (missing no-arg constructor): java.nio.HeapByteBuffer

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While serializing ByteBuffer using Kryo we will run into the following issue. Class cannot be created (missing no-arg constructor): java.nio.HeapByteBuffer To fix this we can create a custom serializer that will take a ByteBuffer and serialize it to and from Kryo. Serializer is rather simple all we need is two pieces of data, length of […]

java

PhantomSQL 2.0

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Since the beginning of this project, I have learned many lessons. First of all the syntax of the language was to closely related to SQL, as this was the language that I wanted to mimic and fit into this framework. Main reason for that was that I wanted something familiar to the end user, I […]

java

Generate ID from UUID

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This is a method to generate a long id in the positive space. There are few issues to consider with this method – UUID is 16 bytes / 128 bits – Long is 8 bytes / 64 bits This means that we will loose some information, if we don’t want to lose that we could […]

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Configuring Java JDK on Ubuntu

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This is an easy way to configure java on a linux box, all this information is available online. First we need to obtain the build. sudo wget http://192.168.201.47:8000/jdk-7u75-linux-x64.gz Extract from tar sudo tar xzvf jdk-7u75-linux-x64.gz Create symbolic link so we can later update the version sudo ln -s /opt/jdk1.7.0_75/ /opt/java we edit the /etc/profile and […]

development

Starting jetty via command line an nohup

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Somehow I am getting problems starting Jetty via service jetty start We will be using unix command called nohup “Nohup is a unix command, used to start another program, in such a way that it does not terminate when the parent process is terminated.” I have opted out for using this nohup java -jar start.jar […]

java

Calculate centroid of 2D non crossing polygon

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Calculate centroid of 2D non crossing polygon, To accommodate that points are correct using Gift wrapping algorithm(Finding Convex Hull) Test case   import static org.junit.Assert.assertEquals; import static org.junit.Assert.assertNotNull;   import java.awt.Point; import java.util.ArrayList; import java.util.Arrays; import java.util.List;   import org.junit.Test;   public class MathUtilTest {   @Test public void computeCentroidWithHull() { Point p1 = new […]

java

Find Convex hull of given points using Gift wrapping algorithm

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Find Convex hull of given points using Gift wrapping algorithm This is implementation of Grift wrapping algorithm for finding convex hull.   private static final Integer ZERO = new Integer(0);     /** * Find Convex hull of given points * * @ref http://en.wikipedia.org/wiki/Gift_wrapping_algorithm * @param vertices * @return */ private static List<Point> findConvexHull(final List<Point> […]

java

Convert Leptonica PIX data into Java BufferedImage

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This snippet allows us to convert Leptonica PIX data into Java BufferedImage, in my case the pix->data could be compressed using zlib so I am decompressing before recreating image. We are assuming here that this is bi-tonal image(1 bpp) File used in example : Pix data compressed used ZLib Pix data decompressed Image represented by […]

java

Convert Leptonica PIX data to Java BufferedImage

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This snippet allows us to convert Leptonica PIX data into Java BufferedImage, in my case the pix->data could be compressed using zlib so I am decompressing before recreating image. We are assuming here that this is bi-tonal image(1 bpp) Sample Usage BufferedImage image = LeptonicaUtil.convert(zlibData, width, height, 1); ImageIO.write(image, "png", new File("C:/temp/test.png")); BufferedImage image = […]