1.0 Table of Contents

1.1 Why learn Java?

  • Widely Used:
    • web development
    • mobile app development
    • enterprise software
    • scientific computing
    • etc
  • ample resources
    • libraries
    • frameworks
    • tools for learning and building Java application
  • platform independence
    • write code once
    • run on any operating system that supports Java
  • Android applications
    • opportunities to develop for the Android platform
  • emphasis on OOP concepts
    • object-oriented programming
    • fundamental to modern software development
  • reliability
    • memory management
    • exception handling
    • help create stable and secure applications.
  • good scalability
    • build applications small or large
    • enterprise-level systems
    • a versatile language

1.2 Fundamentals of the Computer

1.2.1 Computer Logic

a

1.2.2 CPU Instructions

z=x+y;

LOAD x
ADD  y
STORE z

1.2.3 Programming Languages

  • High-level languages
    • Java
    • Python
    • C++
    • C#
    • etc
  • wasier to understand than assembly
  • must be translate to machine code to run

1.2.4 Compile Java

  • Java is a compiled language
  • Java source code is compiled into bytecode a

1.3 First Program

go to repl.it and create a new Java project

1.3.1 HelloWorld.java

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

1.3.2 Program Structure

class CLASSNAME{
  public static void main(String[] args) {
    // code goes here
  }
}

1.3.3 Output to the Console

System.out.println("some string");

1.4 Types

  • Java is a statically typed language
    • variables must be declared before they can be used

1.4.1 Primitive Data Types

Type Description Size Range
byte 8-bit signed integer 1 byte -128 to 127
short 16-bit signed integer 2 bytes -32,768 to 32,767
int 32-bit signed integer 4 bytes -2,147,483,648 to 2,147,483,647
long 64-bit signed integer 8 bytes -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
float 32-bit floating point 4 bytes 3.4e-038 to 3.4e+038
double 64-bit floating point 8 bytes 1.7e-308 to 1.7e+308
boolean true or false 1 bit true or false
char 16-bit unicode character 2 bytes 0 to 65,535

on top of these, Java have support for a character string type, called String

1.4.2 Default Values

Type Default Value
byte 0
short 0
int 0
long 0L
float 0.0f
double 0.0d
boolean false
char ‘\u0000’
String null

1.5 Variables

variables are named location that stores a value of one particular type

1.5.1 Variable Declaration

type name;

Example:

int x;
String foo;

1.5.2 Variable Assignment

name = value;

Example:

int x;
x = 5;

String foo;
foo = "bar";

1.5.3 Variable Initialization

type name = value;

Example:

int x = 5;

String foo = "bar";

1.5.4 HelloWorld2.java

public class HelloWorld2 {
  public static void main(String[] args) {
    String message = "Hello World";
    System.out.println(message);
    message = "Hello World 2";
    System.out.println(message);
  }
}

1.6 Operators

symbols that perform operations on operands operands are variables and values that operators act on

1.6.1 Arithmetic Operators

Operator Description Example
+ addition x + y
- subtraction x - y
* multiplication x * y
/ division x / y
% modulus x % y
++ increment x++
– decrement x–

1.6.2 Assignment Operators

Operator Description Example
= assign x = y
+= add and assign x += y
-= subtract and assign x -= y
*= multiply and assign x *= y
/= divide and assign x /= y
%= modulus and assign x %= y
… … …

1.6.3 Comparison Operators

Operator Description Example
== equal to x == y
!= not equal to x != y
> greater than x > y
< less than x < y
>= greater than or equal to x >= y
<= less than or equal to x <= y

1.6.4 Logical Operators

Operator Description Example
&& logical and x > 0 && x < 10
|| logical or x < 0 || x > 10
! logical not !(x == y)

1.6.5 Bitwise Operators

Operator Description Example
& bitwise and x & y
| bitwise or x | y
^ bitwise xor x ^ y
~ bitwise compliment ~x
« left shift x « 2
» right shift x » 2
»> unsigned right shift x »> 2
… … …

1.6.6 Order of Operations

The standard order of operations in math

  1. Parentheses
  2. Multiplication and Division
  3. Addition and Subtraction

1.6.7 DoMath.java

class DoMath{
  public static void main(String[] arguments){
    double score = 1.0 + 2.0 * 3.0;
    SSystem.out.println(score);
    score = score / 2.0;
    System.out.println(score);
  }
}

1.6.8 DoMath2.java

class DoMath2{
  public static void main(String[] arguments){
    double score = 1.0 + 2.0 * 3.0;
    System.out.println(score);
    double score2 = score / 2.0;
    System.out.println(score);
    System.out.println(score2);
  }
}

1.6.9 String Concatenation

you can use the + operator to concatenate strings

String message = "Hello" + " " + "World";
message += "!";
//message = "Hello World!"

1.7 Assignment 1 - Falling Object

Compute the position of a falling object and print it

  • use the equation
  • position = 0.5 * g * time * time + initialVelocity * time + initialPosition
  • where g is the gravity constant -9.8 m/s^2
  • position is in meters
  • time is in seconds
  • initialVelocity is in meters per second
  • initialPosition is in meters

if time is 10 seconds, initialVelocity is 0, and initialPosition is 0, then the position should be -490.0m

class FallingObject{
  public static void main(String[] args){
    /*
     * Steps to solve the problem
     *  1. Declare variables
     *  2. Assign values to variables
     *  3. Compute the position
     *  4. Print the result
     */
  }
}

View Solution

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