How does Java Work?

• Java programs (".java") are compiled to bytecode (".class") files, not machine language.
• Bytecode is the intermediate code produced by the Java compiler that is interpreted by a Java Virtual Machine (JVM)
• The JVM must exist on the machine (often included in the web browser)
• Bytecode is completely portable.
• Java language is case sensitive. (fillOval <> Filloval)

Types of Java Programs

• Applications
  • All ".class" files must exist locally
  • Meant to be run with the command line interpreter
  • If you want a GUI interface, the program must create a window
  • Access to "standard input"(keyboard) and "standard output" (monitor)
• Applet
  • A Java program which is embedded as part of a web page
  • GUI drawing surface provided on the web page

Java Versions

• Please check with your teacher on what version of Java we are using and what version of a editor we are using as their is a increasing cycle of updates were versions are changing every 6 months.