1. JAVA Programming Environment © Juhani Välimäki 2003

2. Java programming language Java source code = text that a programmer can understand Windows operating system in PC Linux operating system in bigger computer Java-virtual machine (Java VM) in Windows operating system Java virtual machine in Linux operating system Java VM Mac OS in PC Java VM Symbian OS in mobile phones Java virtual machines make it possible to run the same Java program in different systems and devices text editor Java compiler for Java virtual machine Java program that runs inside a Java virtual machine © Juhani Välimäki 2003

3. Java SDK (Software Development Kit) JRE (Java Run-Time Environment) Java programming environment Hello.java - Java source code made by the programmer XYZ operating system in ZYX machine Java virtual machine makes it possible to run the same Java program in different systems text editor Java language compiler Hello.class -Java program runs inside the Java virtual machine Environment variable tells where to look for Java classes: CLASSPATH=.;C:\java\keyboard\;D:\...... Keyboard.class Own classes may also provide services for our new applications My.class Java API System.class System.out.print() Java virtual machine (Java VM) API (Application Programming Interface) tells how to use ready-made Java services © Juhani Välimäki 2003