305 lines
4.0 KiB
Plaintext
305 lines
4.0 KiB
Plaintext
Application
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Programming
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Hend Alkittawi
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Java Basics
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Introduction to Java Concepts and
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User-defined Java Classes
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CONCEPTS
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JAVA
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OBJECT
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- Released in early 1990s
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- Defined by a class
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- Object-oriented
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- A class is a reusable
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- Java SE, Java EE, Java ME
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software components
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- Non-primitive data type
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CONCEPTS
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JAVA APIs
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- Application Programming
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Interfaces
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- Collections of existing
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classes and methods in the
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Java class libraries
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JDK
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- Java Development Kit
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- Includes compiler, loader,
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debugger, JRE, and other
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tools for Java development
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CONCEPTS
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JVM
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- Java Virtual Machine
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- A part of the JRE that
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IDE
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- Integrated Development
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Environment
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executes bytecodes.
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- A software that provides
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- Bytecodes are platform
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comprehensive facilities
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independent (portable)
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for software development.
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WHY DO WE USE OBJECTS?
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●
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Let us discuss the difference between
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○
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Write a program to read n number of values in an array and
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display them in reverse order.
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○
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Write a program to calculate x raised to the power n (xn).
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○
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Write a program to swap two numbers.
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and
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○
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Small Scale Applications
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OBJECT ANALOGY
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BLUEPRINTS
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My Car
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color, …
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accelerate, …
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Your Car
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Some Car
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color, …
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accelerate, …
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color, …
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accelerate, …
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JAVA OBJECTS
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public class Car {
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Class Declaration
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private int colorID;
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private double speed;
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public void setSpeed(int s){
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speed = s;
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}
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public void accelerate(){
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speed = speed + 70;
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}
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Attributes / Instance Variable(s)
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Behaviors / Method(s)
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public static void main(String[] args){
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Car myCar = new Car();
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myCar.setSpeed(50);
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}
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}
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Car.java
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Instantiation (building a Car object)
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OBJECT ANALOGY
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BIOLOGICAL
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CLASSIFICATION
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My Dog
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breed, …
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bark, …
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Your Dog
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breed, …
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bark, …
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Some Dog
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breed, …
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bark, …
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JAVA OBJECTS
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public class Dog {
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Class Declaration
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private int breedID;
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Attributes / Instance Variable(s)
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public void bark(){
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System.out.println(＂Woof＂);
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}
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Behaviors / Method(s)
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Dog.java
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public static void main(String[] args){
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Dog myDog = new Dog();
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Instantiation (building a Dog obj)
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myDog.bark();
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}
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}
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THE String CLASS
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-
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The char primitive type stores one character of the Unicode
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character set.
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-
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-
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A string is a sequences of characters.
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-
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can be 0 or more characters long
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-
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"" is the empty string
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The String class facilitates handling multiple characters at
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once.
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-
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A String object can be declared in order to work with strings
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String someStringObject = new String();
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someStringObject = "HI";
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THE String CLASS
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-
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Many String manipulation methods are available, here are some:
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-
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split() method to get an array of Strings from a String, based
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on a delimiter. This object method takes a delimiter as a
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parameter.
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-
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trim() method to clear off any additional space from the text.
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This object method takes no parameters.
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-
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charAt() method to get the character at an index in the string
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[starting with index 0]. This object method takes an index as
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a parameter.
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-
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equals() method to check if two Strings contain the same text.
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This object method takes a String object as a parameter.
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THE String CLASS
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-
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Java also treats string literals as objects
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-
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-
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A string literal is a quoted string: "Sam I am", "Hi", …, etc.
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Examples:
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String strObj = "This is \"a\" String";
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strObj.charAt(0);
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"HI
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".trim();
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escape sequence
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"Hello".equals(strObj);
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●
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Note how we can create/work with string literals as String
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objects.
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JAVA OBJECTS
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public class Dog {
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private int breedID;
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private String name;
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public void bark(String dogBark){
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System.out.println(dogBark);
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}
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}
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public static void main(String[] args){
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Dog myDog = new Dog();
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myDog.bark(＂Woof＂);
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}
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Dog.java
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Class Activity
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public class SimpleLocation {
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private double latitude;
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private double longitude;
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public void setLocation(double lat, double lon){
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latitude = lat;
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longitude = lon;
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}
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}
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public static void main(String[] args){
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SimpleLocation utsa = new SimpleLocation();
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utsa.setLocation(32.9, -117.2);
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}
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What is
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the value
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of
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longitude
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?
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|
||
DO YOU HAVE ANY
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QUESTIONS?
|
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|
||
THANK
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||
YOU!
|
||
|
||
@
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|
||
hend.alkittawi@utsa.edu
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|
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By Appointment
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Online
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