Introduction, Code Structure and Exceptions

• Intro
• Code Structure
• Exceptions to watch out for

Intro

• Write Once, run anywhere
• source code -> javac compiler -> Byte Code -> Execute on Java Virtual Machines
• compared to c and rust java uses much more memory
• The JVM is capable of optimizing your code while it is running

Code Structure

• source file
  • Class Definitions
    • Method definition(s)
      • statements/loc
• Anatomy of a class
  • when JVM starts running, it looks for the class you give at the command line
  • Then it searches that class for a special function - public static void main
  • There has to be one main method at least, not one per class but one for the entire codebase.

Exceptions to watch out for

• Booleans aand others are not compatible in Java

  int x = 1
  while(x){}
  

  • The above piece of code will give type casting error as only boolean are allowed for conditional testing
• The == operator can be used to compare two variables of any kind, and it simply compares the bits.

      int a = 3;
      byte b = 3;
      if (a == b) { // true }