If you want to build native applications in Android, you've got to know Java---there's no way around it. Yes, there are tools like PhoneGap, Titanium etc. but you will eventually hit limitations and ceilings if you choose to code on non-native development platform. So learn Java, it's not that bad.

1. Set up the environment

Whether you are working on Windows, Linux or OSX, the downloads can be found at Oracle Technet site. Choose just the JSE without the bundles, to keep it simple.

OSX (Lion and Mountain Lion) actually has a simpler way of downloading. Open a Terminal.app, then type java on the command line. OSX wizards will kick in and ask you to download the JDK. Just sayyes to prompt and Java installation will kick in.

If you are using Windows, you will download the JDK (Java Development Kit), get the latest stable release. Be careful that you are downloading the JDK and not the JRE (Java Runtime Environment) only, you need the JDK to create Java apps.

Install what you downloaded, it will guide you through the installation process. The questions are straight forward so they don't need to be expounded here.

Set up the PATH and CLASSPATH variable

NOTE for OSX Users - do absolutely nothing, the CLASSPATH AND PATH variable are already setup for you

On Windows;

Open the System window via the Control Panel, go to Advanced, then Environment variables
Create a variable named JAVA_HOME, the value is where the JDK is installed, if you said yes to the defaults of the installation, it must have been in c:Files1.7xxxxxx.
Edit the PATH variable (on the same window). There is an edit button for the PATH variable.
Append this entry to the PATH variable - ;%JAVA_HOME;.%. The semicolons and the dot are pretty important, so type this slow. If you forget to put these in, you will encounter Bad command or file name kinds of errors later when you execute java and javac
Create another variable names CLASSPATH, put the value %JAVA_HOME.jar;.% -- again, don't forget the semi colon and the dot at the end

2. Get some tools

Get Apache Ant and a decent program editor. Yes you can use notepad, you can use vi, even nano---that is really up to you. I won't even prescribe an editor at this point, this is the subject of a really intense, almost-religious but quite pointless debate. Just keep coding and try out a couple of editors. Don't get cheap, not because it's free it is the best. I like opensource, I love opensource, but it doesn't mean I will always use it. Choose the best tools for the job, even if it costs money.

With that disclaimer out of the way, I do use the following editors; Vi and TextMate (if you are on the Windows platform, the e-TextEditor is fine too)

3. Learn how to write the simplest programs

Do the Hello World program. It's mundane, boring and dry but its the simplest program. You need to know how to write the simplest programs before you can try out the more complex ones. This is a larger discussion, so I wrote it here

4. Learn the keywords of Java

There are a couple of things you will name in Java---meaning, you will think of the name and declare it in your code. These are names of classes, variables, methods, interfaces, parameters passed to methods and packages. Collectively, these are known as Java identifiers.

Rules to remember when creating identifiers

You can use alphanumeric characters, but the first letter can't be a number
You can't use special characters, but you can use the dollar sign and underscore
You can't use a Java keyword (also known as reserved word). You also can't use a Java literals like true, false or null

The Java keywords

for while do throw
case try catch return 

goto [not used]

break continue

byte short int long float double boolean char

if switch throws else

finally class interface implements extends static new this super

public private protected package default

native transient synchronized import instanceof volatile 
void abstract final assert enum strictfp 

const[not used]

5. Dig some OOP, dig a lot of it

OOP is short for Object Oriented Programming. Java is an object oriented language. Sure you can write all of your codes inside public static void main, but that will not take you far in Android when you encounter stuff like class MySplashPad extends Activity.

OOP is so entrenched in Java---in fact, I think a little bit too entrenched that some developers I know get over excited about creating objects, so they create a gazillion of it. Anyway, I hope you learn temperance about creating objects in your own coding journey, but the point remains, you need to know OOP. Read more here ...

Learn how Java treats value types and reference types
Discover how GC works
Learn the data types
Exercise on some operators

10. Dig the control structures, so you can learn block level practices

Your ability to direct and command the flow of control in your program is one of the defining skills for a programmer. There are basically 3 ways that you can arrange the commands in your program code. They are;

You can execute commands one after another -- sequencing
You can execute certain commands when certain conditions are met -- branching
You can keep on repeating certain commands while certain conditions are still true -- looping or iteration. Continue reading about control structures ...

Learn how Java does Exception handling
Some tinsy bitsy java.lang.Util
Some tinsy bitsy I/O
Learn parameter passing
Now, the Thread
Do the simplest UI in java.swing
Do the simplest event handling (actionListeners)
Learn how to use inner classes
Do some basic CRUD (Create, Read, Update, Delete) using SQLite
Dig (but not too deep) some sockets
Exercise on some httpClient programs
Get some XML
Learn ANT a little bit

Are you ready for Android Programming?

Miyerkules, Enero 23, 2013

How much Java do you need for Android Development?