Java was initially a programming language created by Sun Microsystems by James Gosling. Oracle is now the owner of Sun and Java. Java is Oracle’s trademark. Java has become more than a language over time. Java is now a complete platform that includes standard APIs, open-source APIs, tools and a large developer community of millions. Although it may seem confusing, you will soon get a better understanding of Java and be able to start using it.
Java is often referred to as a variety of parts of the overall concept. Java is much more than a programming language. All these “meanings” can seem confusing to a beginner. I will try to explain them briefly so that you understand what they mean. These are the most common Java concepts:
Why Java Programming Language?
Java is an easy language to learn. Its syntax is simple and clear. It is based upon C++, so it is easier to learn for programmers who are familiar with C ++).. Java has eliminated many confusing and seldom-used features, e.g. explicit pointers, operator overloading, etc. Java provides automatic garbage collection and memory management. This automatically collects unused objects.
Java is an object-oriented programming languages. OOP simplifies the program by breaking it down into multiple objects. These objects can be used to bridge data flows from one function to the next. It is easy to modify the data and functions according to the program’s requirements.
Java is first and foremost a programming language. This means that the Java language specification clearly defines what elements make up the Java Programming Language. In other words, what the Java language can do.
Java Bytecode
Java programs written in Java language are converted into Java bytecode that can be executed using the Java Virtual Machine.
The Java bytecode is saved in binary.class files.
Java Virtual Machine
Java is an interpretable language. What does this mean? The Java language is then compiled into Javabytecode. The Java Virtual Machine then executes this Java bytecode.
The Java Virtual Machine can be compared to a computer. It can execute Javabytecode in the same way as a PC can execute assembly instructions.
The Java Virtual Machine can be used on many operating systems including Windows, Mac OS, Linux and IBM mainframes. Solaris is also supported. If your Java program runs on a Java Virtual Machine running on Windows, it will normally run on a Java Virtual Machine running on Mac OS or Linux. There are occasions when your apps behave differently depending on the OS, but they generally behave exactly the same. Sun said that this was “Write once, Run anywhere”.
The Java Virtual Machine can be used as a program by itself. Start the JVM, and tell it which Java code to run. This is usually done using a command-line interface (CLI), such as e.g. Bash is the command-line interface in Windows. The command line tells the JVM which Java class (bytecode), you want to execute.
Java APIs
You can package components in Java into APIs (Application Programming Interfaces), which can then be used by other Java developers in their Java applications. Many of these components are included in Java. These components are called the standard Java APIs. These APIs allow Java programs to access files on the local system and network, as well as many other resources.
You don’t have to program your own Java APIs, but the standard Java APIs offer a lot more functionality than you would normally need. APIs make it easier to develop your applications.
All Java applications have access to the standard Java APIs. The Java Runtime Environment (JRE), or the Java SDK, which includes a JRE, include the standard Java APIs.
Java Runtime Environment (JRE)
The Java Runtime Environment is the Java Virtual Machine. It also contains the Java Standard Edition’s standard Java APIs. The JRE has enough resources to run a Java program, but not to compile it.
Java Software Development Kit (Java SDK)
Java Software Development Kit (Java SDK), is the JRE and Java compiler. It also includes a number of other tools.
The Java SDK is required to create Java programs. The JRE does not suffice. The Java SDK includes the Java compiler, which converts your.java source files to byte code.class files.
Some Java servers might also require some of the JDK tools to, e.g. compile JSPs (Java Server Pages) into Java byte code. It is not sufficient to run the JRE on the server in this case. To ensure that the Java SDK is available to the server, you must use it in its entirety.
Java Code Conventions
The Java Code Conventions provide guidelines for how to format Java code and how to name variables, classes, files, etc. These conventions are not mandatory, but many developers do.
Java Standard Edition (JSE)
Java has three distinct APIs or “profiles”, as some prefer to call them.
Java Standard Edition is available for standalone and desktop applications.
Java Enterprise Edition is for creating and executing Java components embedded in Java servers.
Java Micro Edition is for creating and executing Java apps on mobile phones and embedded devices.
The Java Standard Edition includes the Java APIs needed to run standalone desktop applications and command-line applications. The Java Standard Edition includes both a JRE as well as a JDK.
Java Enterprise Edition (JEE)
The Java Enterprise Edition includes many additional tools and APIs to execute Java components within a Java Enterprise Server. These are examples of enterprise Java components:
Java Application Servers
Java Enterprise Edition (Jakarta EE), is a specification. Software vendors like IBM, Oracle etc. This specification is free for them to implement. They have. They are often called Java Application Servers because they can run Java applications and offer a variety of standard services.
Java Micro Edition
Java Micro Edition is a Java version that’s targeted at embedded devices such as PDAs and mobile phones.
Sun Microsystems was the original developer of Java programming language. James Gosling initiated it and released it in 1995 as a core component of Sun Microsystems Java platform.
Java SE 8 is the latest Java Standard Edition release. Multiple configurations have been created to fit different platforms and the advances in Java. J2EE is for Enterprise Applications and J2ME is for Mobile Applications.
The J2 versions have been renamed Java SE, Java EE and Java ME. Java guarantees to be write once, run anywhere.
Why Java?
Java is Object-Oriented – Everything in Java can be considered an object. Java is extensible because it is based upon the Object model.
Platform Independent – Java, unlike many other programming languages like C or C++, is not compiled into a platform specific machine but into platform independent code. This byte code can be distributed via the internet and interpreted on any platform by the Virtual Machine (JVM).
Architecture-neutral – The Java compiler generates an object file format that is architecture neutral. This makes the compiled program executable on multiple processors when there is a Java runtime system.
Portable – Java is portable because it is architecture-neutral and does not depend on any implementation aspects. Java compiler is written in ANSI C, with a clear portability boundary that is a POSIX part.
Simple – Java was designed to be simple to learn. It would be simple to grasp the OOP Java concept.
Secure – Java’s secure feature allows you to create virus-free and tamper-free applications. Public-key encryption is used to authenticate users.
Robust Java focuses primarily on runtime and compile-time error checking to reduce the likelihood of error.
Multithreaded – Java’s multithreaded function allows you to create programs that can do multiple tasks at once. This design feature allows developers to create interactive applications that run smoothly.
Distributed – Java was designed to work in a distributed environment like the internet.
Interpreted – Java byte code can be translated to native machine instructions on the fly and is not stored anywhere. Because linking is an incremental, lightweight process, the development process is faster and more analytical.
High Performance – Java can achieve high performance through the use of Just-In-Time compilers.
Dynamic – Java can be considered more dynamic than C++ or C++ because it adapts to changing environments. Java programs can store a lot of run-time information which can be used to verify or resolve accesses to objects.