Introduction To Java

James Gosling created Java in 1995 while working at Sun Microsystems. Later, Oracle Corporation acquired that company. Java is a class-based, object-oriented programming language that is simple to learn and is intended to have as few implementation requirements as feasible. In Java, writing, compiling, and debugging programmes is very simple. Java also supports the development of modular software and reusable code. Java applications are compiled to byte code that can run on any Java Virtual Machine. Java's syntax is comparable to that of C/C++.

In 1991, a team of Sun engineers known as the Green team initiated the Java language. The team members are James Gosling, Mike Sheridan, and Patrick Naughton. The first public implementation of Java (Java 1.0) was released in 1996. It provides no-cost -run-times on popular platforms. Java1.0 compiler was re-written in Java by Arthur Van Hoff to strictly comply with its specifications. Then, with the arrival of Java 2, it had multiple configurations built for different types of platforms.

Sun Microsystems approached the ISO standards committee in 1997 with the intention of formalising Java; however, it quickly withdrew from the process. Sun used to offer the majority of their Java implementations for free, despite the fact that they were proprietary software. Through the sale of licences for specific goods like the Java Enterprise System, Sun generated revenue from Java.

Sun Microsystems released much of its Java virtual machine as free, open-source software on November 13, 2006. Then, the company completed the process on May 8 by releasing all of the JVM's core code under open-source distribution terms.

Java was developed using simple, reliable, secure, high performance, portable, multi-threaded, interpreted, dynamic, etc. Nowadays, Java is utilised in mobile devices, internet programming, gaming, and e-commerce, among other things.

Initially, the name of this programming language is OAK. The name Oak was used by Gosling after an oak tree that stood outside his office. Later, the team opted to rename it to a name such as Silk, Jolt, revolutionary, DNA, dynamic, etc. All of these names were simple to pronounce and spell, yet they all aimed to capture the essence of technology. According to James Gosling, Java and Silk were two of the most popular names, and since Java had a distinctive name, most people chose it.

Java is the name of the Indonesian island where the first coffee, sometimes known as java coffee, was made. And James Gosling came up with this moniker while enjoying coffee close to his workplace. Java is merely a name; it is not an acronym.

Before learning Java, we need to be familiar with these common terms of Java.

Java Virtual Machine(JVM)

This is generally referred to as JVM. There are three execution phases of a program which are write, compile and run the program. Writing a program is done by a java programmer. The compilation is done by the JAVAC compiler which is a primary Java compiler included in the Java development kit (JDK). It takes the Java program as input and generates bytecode as output. In the Running phase of a program, JVM executes the bytecode generated by the compiler.

Now, we understood that the function of Java Virtual Machine is to execute the bytecode produced by the compiler. Every Operating System has a different JVM but the output they produce after the execution of bytecode is the same across all the operating systems. This is why Java is known as a platform-independent language.

Bytecode

The Javac compiler of JDK compiles the java source code into bytecode so that it can be executed by JVM. It is saved as .class file by the compiler. To view the bytecode, a disassembler like javap can be used.

Java Development Kit(JDK)

While we were using the term JDK when we learn about bytecode and JVM. So, as the name suggests, it is a complete Java development kit that includes everything including compiler, Java Runtime Environment (JRE), java debuggers, java docs, etc. For the program to execute in java, we need to install JDK on our computer in order to create, compile and run the java program.

Java Runtime Environment (JRE)

JDK includes JRE. JRE installation on our computers allows the java program to run, however, we cannot compile it. JRE includes a browser, JVM, applet supports, and plugins. For running the java program, a computer needs JRE

Garbage Collector

In Java, programmers can’t delete the objects. To delete or recollect that memory JVM has a program called Garbage Collector. Garbage Collectors can recollect the objects that are not referenced. So Java makes the life of a programmer easy by handling memory management. However, programmers should be careful about their code whether they are using objects that have been used for a long time. Because Garbage cannot recover the memory of objects being referenced

ClassPath

The classpath is the file path where the java runtime and Java compiler look for .class files to load. By default, JDK provides many libraries. If you want to include external libraries they should be added to the classpath.