A Java compilers translate a Java source file (.java) into a Java class file (.class).
A Java class file runs on any platforms which has a Java Runtime Environment (JRE).
The Java class file is called Java bytecode because it is interpreted in a byte unit by a Java interpreter (java.exe).
- Java Runtime Environment (JRE)
A JRE is what you need to run a Java program.
A JRE is composed of a Java Virtual Machine (JVM) and Java APIs and other files, which help a JVM to run Java bytecode.
A JVM actually runs Java bytecode.
- Java Development Kit (JDK)
- A JDK is composed of a JRE and tool programs, which it is necessary to develop Java.
Java is object-oriented programming language.
Java supports basic concepts of object-oriented programming, such as: