Basic JAVA for Android Development

Nattapong Tonprasert

Reference

• Head First Java, O'Reilly

Introduction

The Way Java Works

Installation Java Platform (JDK)

• Download : http://www.oracle.com/technetwork/java/javase/downloads/index.html

Look how easy it is to write java

Look how easy it is to write java

Code structure in Java

Code structure in Java

source file

class file

method 1 statement

method 2 statement

Code structure in Java

public class Dog { !!!!}

class

public class Dog { void bark () { !! } }

method

public class Dog { void bark () { statement1;!! ! statement2; } }

statements

Anatomy of a class

Writing a class with a main

public class MyFirstApp {! public static void main (String[] args) { System.out.println("I Rule!"); System.out.println("The World!"); } }

Statements

int x = 3;String name = "Dirk";x = x * 17;System.out.print("x is " + x);double d = Math.random();// this is a comment

Conditionif (x == 10) { System.out.println("x must be 10");} else { System.out.println("x isn't 10");}!if ((x < 3) && (name.equals("Dirk"))) { System.out.println("Gently");}!if ((x < 3) || (name.equals("Dirk"))) { System.out.println("Gently");}

Looping

while (x > 12) { x = x - 1; System.out.println("x is " + x);}!for (x = 0; x < 10; x = x + 1) { System.out.println("x is " + x);}

Classes and Objects

Classes and Objects

Classes and Objects

Classes and Objects

thinking about objects

When you design a class, think about the objects that will be created from that class type. Think about

• things the object knows

• things the object does

thinking about objects

What’s the difference between a class and an object?

• A class is not an object (but it’s used to construct them)

• A class is a blueprint for an object

Encapsulation

• public

• private - self class

• protected - self package

Class GoodDogclass GoodDog { private int size; public int getSize() { return size; } public void setSize(int s) { size = s; } void bark() { if (size > 60) { System.out.println("Woof! Woof!"); } else if (size > 14) { System.out.println("Ruf! Ruf!"); } else { System.out.println("Yip! Yip!"); } }}

GoodDog Test Drive

public class GoodDogTestDrive { public static void main (String[] args) { GoodDog one = new GoodDog(); one.setSize(70); GoodDog two = new GoodDog(); two.setSize(8); System.out.println("Dog one: " + one.getSize()); System.out.println("Dog two: " + two.getSize()); one.bark(); two.bark(); }}

Static variables

Static variables

Static variables

class Player { static int playerCount = 0; private String name;! public Player(String n) { name = n; playerCount++; }}!public class PlayerTestDrive { public static void main(String[] args) { System.out.println(Player.playerCount); Player one = new Player("Tiger Woods"); System.out.println(Player.playerCount); }!}