App Development

Day 1: Introduction to Java

and Android Studio

Administrative Comments

What you will do in this course:
- Be introduced the basics of Android app development
- Be introduced to the Android Studio IDE
- Learn Java through Android app development

Everyone gets respect
No food; water only
Leave no one behind
- "Three before me": ask at least three peers before asking an instructor
No phones/tablets/other miscellaneous devices except with instructor approval
- In Android Studio, we will be using smartphone emulators, which are emulators of almost every Android smartphone you can think of, so you won't need your phones
No gaming/VPNs/extraneous activities
- Tip: be very careful what you do on Punahou WiFi

Because there are a lot of you and probably a wide skill range, we would like to better tailor the course to you guys
We need to gauge overall programming knowledge to better instruct you all
Please follow the instructions in the next slide closely
- We will not answer questions that have been answered on the slide

Open Chrome
Go to this URL:
https://www.surveymonkey.com/r/YW3FL77
Take the survey and press "Done" when done
- Do NOT attempt to look up the answers
- If you did not know much, that is fine; we just want to know what to teach

We will put you into random groups
It is okay if you didn't know any of the answers
- But please try to understand them and ask your group members for help
Introduce yourself to your group members
Come up with answers to the quiz questions
- You MAY use Google
We will then slowly merge the groups until the entire class has a solution set to present

Import GeoQuiz app from GitHub
- https://github.com/junior-devleague/AndroidAppDevelopment
- Click on "GeoQuiz.7z"
- Download and extract
Open Android Studio
- File > Open > Select GeoQuiz directory

Basically telling the computer what to do
People write out code, which is translated into machine language and executed
Code is read sequentially, top-down
- The computer processes every line of code that you write and executes it exactly as written

Reusable programming objects
Like manufacturing multiple cars; instead of redesigning each part every time, a blueprint is made and the cars are created using that blueprint
- When the class is made into a real working thing, it's called an object
- Blueprint == class

Code is written in a programming language (in this case, Java)
That human-readable code is compiled into machine language so the computer can execute it using its OS or processor
- Java is special, it compiles into bytecode, which is run by the JVM
Java Virtual Machine (JVM)
- Abstract computing machine that mimics a processor so it can execute Java bytecode
- Enables a computer to run a Java program

Basically grammar for computers
Someone give an example of a grammatically correct ENGLISH sentence!
Now move around the punctuation and randomize the capitalization and scramble the words
There's a grammar for every language, including computer language -- it's called syntax!

class hello_world {
    public static void main(String[] args) {
        System.out.println("Hello world!");
    }
}

class hello_world {
    public static void main(String[] args) {
        int number = 5*5+10;
        System.out.println(number);
    }
}

= is assignment
- ex int num = 10;
== is comparing values and checking for equality
- Returns true or false
- ex num == 10;

A variable is something that store data
Must follow certain naming conventions
- NEVER start with a number
- NO spaces
  - Use underscores or camel casing
  - ex thisIsCamelCasing
- No special characters (*,.!@#;: etc)
In Java, they must be typecasted
- ex int varName = 10;
- ex String varName = "This is a string.";
Syntax: dataType variableName = value;
- When initializing, if you don't assign a value, it gets set to null, 0, or false.