JAVA EE: Java Tutorial : The Java Programming Langauage

Tuesday, 21 July 2015

Java Tutorial : The Java Programming Langauage

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What is Java?

Java is one of the world's most popular, reliable, and versatile programming languages. From enterprise web applications to mobile apps and large data systems, Java powers countless everyday digital platforms.

When writing a program in Java, your source code is saved in plain text files that end with the .java extension (for example, HelloWorldApp.java).

From Source Code to Bytecode

Computers cannot understand human-readable Java code directly. Here is how Java bridges that gap:

The Java Compiler: The compiler takes your .java file and compiles it into a .class file (such as HelloWorldApp.class).
Bytecode: The .class file contains bytecode. Bytecode is the machine language of the Java Virtual Machine (JVM).
Execution: The JVM reads the bytecode instructions and runs your application on your system.

Write Once, Run Anywhere (WORA)

Java's greatest strength is platform independence. Because the Java compiler produces bytecode rather than machine-specific code, the compiled .class file can run seamlessly across different operating systems:

Microsoft Windows
Linux
macOS

Every operating system has its own tailored version of the Java Virtual Machine. As long as a system has the JVM installed, it can run your compiled Java bytecode without needing any changes to your code.