Introduction to Java Technology and Programming Concepts

GREEN

The research project's codename funded/supported by Sun Microsystem in 1991.

C++

The programming language used to create Java.

Oak

The first name of Java.

James Gosling

Creator of Oak/Java.

Java

The name after the name of oak, introduced in May 1995, called after the coffee they drank.

Java Applets

Programs that run spontaneously by a Java compatible browser and can be downloaded without interaction with the user.

Life cycle of Applets

1. Initialization - preparation of information inside applets. 2. Start - Beginning/Starting point of applets. 3. Run - process. 4. Stop / Destroy.

Compiler

A program that translates Java Program to CLASS FILES - bytecodes.

Bytecodes

Compiled format for Java Programs executed by the JVM.

Portability

The ability to run on different operating systems.

JVM (Java Virtual Machine)

A bridge between the apps to OS that allows Java programs to run from different OS and hardware platforms.

Object Oriented

A feature of Java that focuses on objects rather than function or logic.

Dynamic

A feature of Java where decision making happens.

Multi Threaded

A feature of Java that allows programs to run concurrently/simultaneously with better performance.

Architecture Neutral

A feature of Java that allows it to run on any platform.

Five Phases of Java Programs

1. Creating and Editing - where programmers type the needed rectifications and save the program as .java file extension. 2. Compile - where you compile a program to find errors. 3. Load - placing the program in memory (RAM) before it can implement a process. 4. Verify - ensures the java programs entering over the network do not harm the user's files or system. 5. Execute - bytecodes stated in the program will be executed by the JVM.

Java Application

A computer program that performs when you utilize the Java Command to open the JVM.

Comment Lines

Indicated by //, where the user can insert documentation used to improve readability.

Class Declaration

A class declaration for class Welcome. Java programs must have at least one class declaration that is defined.

Body of a Class Declaration

A { indicates the beginning of the body of a class declaration.

Java Application Starting Point

This shows the starting point of a Java application. Items enclosed in parentheses indicate that it is a program building block called method.

Body of the Method

This left brace starts the body of the method.

Action Directive

This directs the computer to do an action.

End of Class Declaration

The right brace ends each class declaration.

End of Method Declaration's Body

This right brace must end the method declaration's body.

Primitive

Built in fundamental types installed already in Java Program.

Non Primitive

It is what the programmers created and not built in.

Data Type

Sometimes called Type.

Variable

Memory spaces that utilize value.

Value

Sometimes called Identifiers or Literals; representation of value.

Boolean

If answerable by True or False.

Numeric

Character - used for single letters, numbers and characters and only use 'SINGLE QUOTES'.

Integral

Integers - whole numbers.

Byte

-128 to 127 (8 bit).

Short

-32,768 to 32,767 (16 bit).

Int

-2,147,483,648 to 2,147,483,647 (32 bit).

Long

-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 (64 bit).

Floating Point

Includes Float - it is up to 1-7 decimal places and Double - it is up to 7 to 15 decimal places.

Packages

Are the best tool for classifying different classes from each other.

User Defined Packages

Made by the programmers.

In Built Packages

Built in packages.

Java.util.scanner

Where we import the scanner class.

Tokens

Series of characters that ends with whitespace (Blank, Tags, Etc.).

Scanner Methods

Methods include in.nextBoolean(), in.nextByte(), in.nextDouble(), in.nextFloat(), in.nextInt(), in.nextLine(), in.next(), in.nextLong(), in.nextShort().

Class Construct

To create an object inside your program.