Yoo Techies

I'm taking my first Tutorial on Java, Let's see how my learning goes 🙂↕

What is Java?

Java is an Object oriented programming (OOP) language, Class based, robust and secured (Java is also a platform).

How to run a Java Program -->>.

Download Java JDk (Java development Kit) .

https://www.oracle.com/ng/java/technologies/downloads

Install and make sure Environmental Variable are been register to your PC/ Mac_Os.

Choose Your choice editor, I will recommend Vscode, Intellij Idea, Netbeans , any more choice.

Create a folder, Create a Java file and save with the extension name (.java).

Example (sample.java).

Write a sample code in java.

public class Code{
    public static void main(String[] args) {
        System.out.println("Hello World!"); //main() is the entrypoint of a java-program
    }
}

Learn to run with Java Compiler as far as java jdk is installed into your system,

Open command prompt and locate your file directory then run javac sample.java.

then a "sample.class" java file will be created, This is because Java compiler runs it in bytecodes.

Next, run java sample.java.

NOTES:

A Java Program should always have an access modifier.

An access modifier is a special keyword that determines if other classes and method in java program can access a class or method.

Access modifiers are (public,private).

Variables.

A variable is a memory location for a value, it can also be said as "A variable is a container that stores data".

"int" is a keyword used to store an integer variable.

Types in Java:

Java Have two types which are: Primitive and Reference.

Primitive is used to store simple values.

Reference is used to store complex objects.

Category of primitive types

1) byte : Which takes 1 byte of memory and can store values from [-128, 127] in Range "The more byte available, "The larger number we can store"".

2) short : Which takes 2 bytes and can store value up to [-32k, 32k] in Range.

3) int : Which takes 4 bytes abd can store value up to [-2b, 2b] in Range.

4) long: Which takes 8 bytes.

byte, short, int and long are used to store number that don't have decimal point.

to store value with decimal point, you make use of float or double.

5) float : Which takes 4 bytes.

6) double : Which takes 8 bytes.

strings

7) char: Which takes 2 bytes and are used to store single character ("A","B","C".) as Range.

8) boolean: Which takes 1 byte of value [True/False].

Reference Type.

String: Which takes any amount of value

Find Scanner usage in InputUsage.java

Expressions in Java(express.java)