Java

Java

• Works left to right, but uses precedence for math
• System is part of the java.lang package, which is automatically imported
• final makes something a constant, and uses THIS_CONVENTION
• You can cast with parentheses - double someNumber = (int) 2.1 + 3.4
• if/else, switch, while, for, logic operators are all the same as JS

Vocab

• Package = Related classes. Token -> Expression -> Statement -> Method -> Class -> Package

Installing

• sudo apt install openjdk-11-jdk-headless

Hello World

// HelloWorld.class
public class HelloWorld {
  public static void main(String[] args){
    System.out.println("Hello, World!");
  }
}

javac HelloWorld.class
java HelloWorld

Types

• int
• String - Compare with .equals, not ==
• double - Default float
• boolean
• char - Get from string with .charAt(position), cast with (char) from unicode

Questions

• Why are some types uppercase and others lowercase?