Programming in JAVA 🚀

Binary Number System

We humans use a decimal, or base-10, numbering system, presumably because people have 10 fingers

Early computers were designed around the decimal numbering system. This approach made the creation of computer logic capabilities unnecessarily complex and did not make efficient use of resources. (For example, 10 vacuum tubes were needed to represent one decimal digit.)

Story behind

To deal with the basic electronic states of on and off, Von Neumann suggested using the binary numbering system

Conversions

Binary Number to Decimal
Decimal Number to Binary

Quiz Time 🔥

Programming in JAVA

What happens behind the scenes?

Why Java is Platform independent.

.java file

(source code)

.class file

(byte code)

Machine Code (0s & 1s)

compiler

interpreter

What happens behind the scenes?

Why Java is Platform independent.

.java file

(source code)

.class file

(byte code)

Machine Code (0s & 1s)

compiler

interpreter

Byte Code doesn't run directly, we need a JVM (Java Virtual Machine) to run this code

Platform Independence?

Byte-Code can run all operating systems

C++

C/C++ Compiler generates a .exe file which is platform dependent.

Java

In Java we get bytecode, JVM converts this bytecode into machine code.

To run byte-code, we need a JVM installed on a machine.

Java is platform independent but JVM is platform dependent.

Software Tools [Recommended] 🤔

IntelliJ Idea (IDE)

https://www.jetbrains.com/idea/download

(Free Community Edition)

JDK

https://www.oracle.com/java/technologies/downloads/#java16

JVM 🤔

Java Virtual Machine

JVM

Java Virtual Machine, or JVM, loads, verifies and executes Java bytecode. It is known as the interpreter or the core of Java programming language because it executes Java code.

First Java Program

Boilerplate Code

//Boilerplate Code
class Main
{
	public static void main (String[] args)
	{	

	}
}

First Java Program

Boilerplate Code

//Boilerplate Code
class Main
{
	public static void main (String[] args)
	{	
    		//Your Code goes here
	}
}

First Java Program

Boilerplate Code

//Boilerplate Code
class Main
{
	public static void main (String[] args)
	{	
    		//Your Code goes here
    		System.out.println("Hello World");
	}
}

Let's learn Java syntax!

1. Hello Java

2. Variables & Data types

3. Typecasting

4. Branching

Next Class

3. Loops

4. More constructs

Variables & Datatypes

Variables come in two types

Primitives
Object References

Boolean - boolean
Character - char
Integer – int
Floating Point – float
Double Floating Point – double

Primitive Data Types

Buckets come in different Sizes!

You can't put a large value into a small cup.

Range of Data Types

Lil bit about Objects!

Stack Memory

vs Heap Memory

in Java

(Separate Class)

Read here

Read Principal, Rate & Time and print Simple Interest.

Sample Input

P = 100

R = 5

T = 2

Sample Output

SI = 10

Simple Interest Calculator

Read 3 Numbers and find their largest.

Sample Input

Sample Output

Largest of 3 Numbers

Learning Outcomes🦸🏻‍♂️

'float' data type used to define

numeric values

with floating decimal points.

'int' divided by 'int' gives a

integer output due to a

concept called Implicit Typecasting.

Branching

if/else tests - do something under this condtion

if ( weather == "rainy"){

          System.out.print("Take an Umbrella");

}

Conditional Statements

Single If

// Single If

int marks = 90;

if (marks > 80) {
	cout << “Let's Party!”;
}

Conditional Statements

// If-Else Block

int marks = 70;

if (marks > 80) {
	cout << “Let's Party”;
}
else{
	cout<< “Work hard next time“;
}

Conditional Statements

If-else-if-else block

// If-Else Block

int marks = 70;

if (marks > 80) {
	cout << “Let's Party”;
}
else if(marks>60){
	cout<<"Good Job";
}
else{
	cout<<"Work hard next time";
}

Homework Challenge 🔥

Electricity Bill Calculator : Given total consumption of a

household in units, write a program to estimate the total bill amount as per the table.

Units	Charges
1 to 100 units	Free
100 to 200 units	Rs. 5/unit
200 to 300 units	Rs.10/unit
300+ units	Rs.12/unit