Layers of Logic

Phase I

The Machine

What Java is, and what is actually running your code.

2 sections36 min of reading8 exercises

Learn the portability problem Java was designed to solve. Then compile and run one program from the terminal, following it from source code through bytecode, class loading, and the local JVM.

When you finish this phase you can

  • Explain why a native binary targets both a processor architecture and an operating system
  • Distinguish portable source code, portable bytecode, and platform-specific native code
  • Follow a Java file from .java to .class to a running program
  • Distinguish the JVM execution engine, a runtime environment, and the JDK tools
  • Write, compile and run a Java program from the command line
  • Identify whether a failure happened during compilation, class lookup, entry-point lookup, or execution
  1. 1.1Why Java ExistsSee why Java was created and how one source file becomes instructions a computer can run.Write once, run anywhereCompilerCore16 min4 exercises
  2. 1.2JVM, JRE, JDK, and Your First ProgramInstall the tools, compile one Java file, and run it from the terminal.BytecodeJVMCore20 min4 exercises