Java classes

Every Java program:

  • must have a class
  • starts from the main method 
  • all code is within classes 

    Interfacing with Java classes

    • Protege export
    • Clojure
    • Org-mode code blocks
    • EMF – Ecore 
    • Jena 
    • JSON API for WordPress?

      Java main method

      To run our program, the main method must be identical to this signature

      public static void main(String[ ] args)

      • Public : anyone can see it
      • Statuc : method can be run without creating an instance of the class containing the main method 
      • Void : method doesn’t return any value 
      • Main : name of the method
      • Main’s parameters are is an array of strings called  args 

      Methods

      A method is a collection of statements grouped together for an operation
      Aka functions 

      Java syntax

      • ​In classes, methods, and other flow-control structures code is always enclosed in curly braces { }.
      • Each code statement must end with a semicolon


      Comments


      • single-line comments  start with two forwars slashes //
      • multi-line comments start with forwars slash followed by asterisk /*  and end vice versa */ 

      /*  This is also a

          comment spanning

          multiple lines */

      Documentation comments

      • generate external documentation of your source code
      • These begin with a forward slash followed by two asterisks, and end with an asterisk followed by a forward slash.

      /** This is a documentation comment */
      /** This is also a

          documentation comment */

      Javadoc is a tool which comes with JDK and it is used for generating Java code documentation in HTML format from Java source code which has required documentation in a predefined format.
      When a documentation comment begins with more than two asterisks, Javadoc assumes that you want to create a “box” around the comment in the source code. It simply ignores the extra asterisks.

      /**********************
      This is the start of a method
      ***********************/

      Variables

      Variables store data for processing.

      A variable is given a name (or identifier), such as area, age, height, and the like. The name uniquely identifies each variable, assigning a value to the variable and retrieving the value stored.
      Variables have types. Some examples:

      int: for integers (whole numbers) such as 123 and -456

      double: for floating-point or real numbers with optional decimal points and fractional parts in fixed or scientific notations, such as 3.1416, -55.66.

      String: for texts such as “Hello” or “Good Morning!”. Text strings are enclosed within double quotes.
      You can declare a variable of a type and assign it a value. Example:

      String name = “Jason”;

      This creates a variable called name of type String, and assigns it the value “Jason”.

      You can use a comma-separated list to declare more than one variable of the specified type. Example: 

      int a = 42, b = 11;

      println method

      • println method prints a line of text 
      • The  System class and its out stream are used to access the println method 

        {
        System.out.println(“Hello World!”);
        }

      WordPress for Android 

      • How many posts can this thing handle?
      • Wish it had a search function ….Do I have to make an Android app with an JSON API … or maybe a searchable Atom/RSS feed? ….maybe there’s a Linked Data input option?

      How to organize my files?

      # State of the file system

      • I have been accumulating text files for about a decade
      • Plain text files are great for cross-platform future-proofing, flexibility VCS ect…..
      • I’m sure plenty of geeks can wrangle their text files just fine with git and text editors ….but it’s not a replacement for backup and sync …..
      • After many hoops, between machines my file system is lookin’ pretty convolded and I have some diffs to do 
      • Emacs can handle thousands of text files no problem but neigjer my text editor nor files are that mobile friendly