September 7th, 2022

What is object-oriented programming?

It’s a collection of ideas.

• Encapsulate code and data
• Abstract data types
  • They hide how they work on the inside
  • “Abstract” = correct behavior, but the inside workings are hidden
• Overloading
  • Changes how an operator works
  • For example, + on integers vs. strings
• Inheritance
  • “I want an object just like another, but slightly different” (without copy and pasting)
  • DRY

People came up with objects because they’re a good model for many things in real life.

Java

• One file per class (unlike C++, which has a header file and body file)
• It’s an interpreted language
  • Java → Machine code for Java Virtual Machine → Execute code on the Java Virtual Machine
• Compilation
  • javac Foo.java compiles Foo.class etc files
  • java Foo runs Foo.class’s public static void main method