Advanced Java Exam Study Notes

Java is an open-Source.
Java is a class based.
Java is high-level programming language.
Java is an object-oriented programming language.
Java is platform independent.
Java programs are compiled into byte code.
Java programming language was created by James Gosling.
Gosling worked along with his team also called the Green Team.
Project were worked on was called Greentalk.
Java 10 enhanced 70+ APIs with new methods and options and removed deprecated APIs and options.
Immutable Collections.
Enhanced Garbage Collection.
Heap Allocation on Alternative Memory Devices
Types of Java applications:

A. Web Application:

Web applications are the applications that run on web browser using servlet, JSP, struts technologies. These technologies create java web applications and deploy them on server.

B. Mobile Application:

These are mobile applications created using java.

C. Standalone Application:

Standalone applications are executed by themselves without the need of other programs and files. Example of such an application is antivirus.

D. Enterprise Application:

Some applications are designed for corporate organizations with the intent to control major process in real time. Such applications are called enterprise applications.

Robust - Java emphasizes a lot on error handling, type checking, memory management, etc. This makes it a robust language.
Multithread - It is an important feature provided by java for creating web applications.
Dynamic - Java is designed to adapt to ever evolving systems thus making it dynamic.
Simple - Java is simple to understand, easy to learn and implement.
Portable - Java is not necessarily fixated to a single hardware machine. Once created, java code can be used on any platform.
Secured - It is possible to design secured software systems using Java.
High Performance - Java uses Just-In-Time compiler thus giving us a high performance.
Object-Oriented - In object-oriented programming everything is an object rather that function and logic.
Platform Independent - Java is write once and run anywhere language, meaning once the code is written, it can be executed on any software and hardware systems.
Interpreted - Java converts high-level program statement into Assembly Level Language, thus making it interpreted.

`JVM / JK / JRE`

The Java Virtual Machine (JVM) is a virtual machine that provides a runtime environment to execute java bytecode.
The java program is converted into java bytecode which is then translated by the JVM into machine code which can be then understood by the CPU to get the output.

The Java Development Kit (JDK) is a superset of JRE and is used to create java applications.
There are three JDK provided by Oracle; Java Enterprise Edition (Java EE), Java Standard Edition (Java SE), and Java Mobile Edition (Java ME).

The Java Runtime Environment (JRE) provides java libraries, the JVM and other files and documents that are needed to run java applications.