scala

Getting a preview image of a PDF file in Scala

Reading Time: < 1 minute In order to have an preview image of an PDF file you can use PDFBox. Here is the simple tutorial to extracting an preview image of an PDF file. Firstly you need to get the pdfbox-jar file & you can get it here. 1. You need to have these following imports. import java.io.FileInputStream import javax.imageio.ImageIO import org.dopdf.document.model.PageDetail import org.dopdf.document.read.pdf.PDFDocumentReader import java.io.ByteArrayInputStream import utils.AmazonUpload import java.io.InputStream Continue Reading

ScalaKnol: Understanding Traits as Stackable Modifications

Reading Time: 3 minutes Traits can be used to modify the methods of a class. The way such modifications are carried out is such that they can stack modifications with each other. Let us take an example. Say, there is a class called ImageProcessor which processes images. Now there are a few modifications required before the image is actually uploaded to your server. If you are using Facebook then Continue Reading

Knolx Session: Data Structures In Scala

Reading Time: < 1 minute This Knolx session we went about discussing data structures. I talked about simple data structures like Queue and Binary Search Tree and their possible implementation in Scala. The idea was to know about a bit of Functional data structures and their implementation in Scala. I then discussed Binary Search Trees and their traversals. Here is the presentation.

Extract a frame image from video in scala

Reading Time: 2 minutes Sometimes it becomes a general requirement to show the preview of a video wherever video gets displayed. Like on YouTube , If you’ll right click on almost any video , you’d find that each video contains a preview image of a frame of that video. Here is a short tutorial for doing the same i.e extracting a frame image from a video in Scala via Continue Reading

ScalaKnol: Understanding Uniform Access Principle

Reading Time: 2 minutes The ScalaKnol series attempts to share a nugget of Scala wisdom every few days or sometimes few times a day. Keep tuned. Today we would look at the Uniform Access Principle. The principle states that the client code or the calling code should not be affected by the decision to implement an attribute as a field or a method. Hence essentially irrespective of whether the Continue Reading

ScalaKnol: Understanding Loan Pattern

Reading Time: 2 minutes Loan Pattern as the name suggests would loan a resource to your function. So if you break out the sentence. It would Create a resource which you can use Loan the resources to the function which would use it This function would be passed by the caller The resource would be destroyed As you would see, the advantages are multifold. First, I am not constrained Continue Reading

ScalaKnol: Why returning a value in finally is a bad idea

Reading Time: < 1 minute For those of us who are coming from an imperative background, we are used to using try catch rather losely. Ok, I am not trying to generalize here but a majority of us do so. When we come to the Scala world, we realise that like other expressions in scala, try-catch-finally would result in a value. The general practice recommended is that finally should be Continue Reading

SICP Chapter 1 Solved with Scala

Reading Time: 3 minutes Ok, let us get the facts right. We have not provided solution to each exercise but the solutions that we have provided would be good for you to understand the concepts. It would also help you realize how efficiently we can use higher order functions in Scala. The Structure and Interpretation of Computer Programs (http://mitpress.mit.edu/sicp/full-text/book/book.html) is a seminal book which helps you reason and understand Continue Reading

Annotations in Scala

Reading Time: < 1 minute In this session, we will learn about annotations. Firstly, we will see the definition of annotation, standard annotations and then we will learn to write our own annotations. As of now, with Scala we can create compile time annotations (could we create runtime ones without resorting to Java?). For example, if you look at the @tailrec annotation in Scala then it would verify that the Continue Reading

SOLID Principles with Scala

Reading Time: < 1 minute It is quite evident what SOLID principles mean for class typed object oriented languages like Java. However, what do they mean for hybrid languages like Scala which merge the Object oriented and functional approaches. In this KnolX session, we tried to decipher what SOLID principles meant for Scala. Though much of what we know about them can be applied to Scala if we code in Continue Reading