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Java Terminology

Java Terminology

Below are some key java terms which helps to understand how java works.
  • Java Virtual Machine (JVM)
  • Bytecode
  • Java Development Kit (JDK)
  • Java Runtime Environment (JRE)

Java Virtual Machine (JVM)

JVM is a program designed to run Java programs across different platforms. There are different versions of JVM for different operating systems (Windows, Mac and Linux). JVM allows running Java programs on any operating system. This makes Java platform independent language. This is one of the primary function of JVM. 

Another important function is Memory management. JVM manages memory through a process called Garbage collection, which continuously identifies and eliminates unused memory in Java programs. Garbage collection happens inside a running JVM. 

Bytecode

Java compiler compiles the Java programs into bytecode. Bytecode then can be executed by using JVM. Bytecode is saved in a .class file. 

Java Development Kit (JDK)

Java development kit provides the tools required to create, compile and run Java programs. JDK includes JRE, compilers and other tools like JavaDoc, Java debugger etc. 

Java Runtime Environment (JRE)

JRE is part of JDK. JRE contains JVM, browser plugins and applets support. 

JRE is to be installed on the system to be able to run the Java programs. In other words, JRE provides the environment to run Java programs. JRE alone is sufficient if the intention is only to run the Java programs and not create them. 

JDK contains both compiler and JRE and enables users to create java programs and run them on the system. 


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