Using HTML5 and other web technologies when developing an application for the android platform simplifies the development process and helps us cooping with the well known android platform fragmentation problem. I chose to write this post in order to point at those cases in which we cannot avoid using Java in our application development for [...]
On November 15th I start delivering a professional course for learning how to develop applications in Java for the android platform. The course includes 180 academic hours, it takes place in HIT and it splits into three parts. The first part covers the topics in Java required for learning android development and it includes extensive [...]
During the first semester of the 2012-2013 academic year that takes place in HIT, I deliver an academic advance course for learning Java and Scala. This course is delivered as part of the academic program for BSc in computer science. You can find the google group of this course at https://groups.google.com/forum/#!forum/hit-scala-october-2012. You can find the [...]
The generic class has the same behavior for all of its possible parametric types. The same generic class can be viewed each time as if it has a different parametric type. For the JVM it doesn’t matter which parametric type we chose to instantiate a generic class with. In all cases, for the JVM it [...]
When using a bounded wild card we can limit the parametric type as if we were saying that it can be any type as long as it extends or implements a specific type we specify. package il.ac.hit.samples; import java.util.Iterator; import java.util.Vector; public class BoundedWildCardSample { public static double calculateTotal(Vector<? extends Shape> vicy) { double sum [...]
When using an array of generic type objects in Java we cannot specify the exact parametric type. This limit exists due to the way generics is implemented in Java (in the compiler level). package il.ac.hit.samples; public class ArraysGenericsLimit { public static void main(String[] args) { MyStack<?> []vec = new MyStack<?>[10]; vec[0] = new MyStack<Rectangle>(); vec[1] [...]
As of Java 7 we can take out the type arguments required to instantiate a generic class as long as the compiler can infer the type arguments from the context. Many developers name the remaining pair of angle brackets as ‘diamond’. package com.abelski.samples; import java.util.LinkedList; import java.util.List; public class GenericsTypeInference { public static void main(String[] [...]
As with Java 7 we can handle more than one type of exception using a single catch block. We should use the ‘|’ operator for putting them together in the same catch statement. When catch handles more than one type of exception the catch parameter is implicitly final. We won’t be able to assign it with [...]
As of Java 7 we can code a try statement that declares one or more resources. Each resource is an object that must be closed after the program is finished. The try-with-resources statement ensures that each resource is closed at the end of the statement. Each object considered as a resource must be instantiated from a class [...]
As of Java 7 we can write a switch case statement that works on strings. This new capability might assist us with writing a shorter code. package com.abelski.samples; public class Demo { public static void main(String[] args) { String operator = args[1]; double numA = Double.parseDouble(args[0]); double numB = Double.parseDouble(args[2]); String result; switch(operator) { case [...]
