Scanner ---> java.util
nextLine (get a line of text from the user)
nextDouble
nextInt

String ---> charAt, length, etc...

Random 
nextInt()
nextInt(upper)
nextFloat()

Math:
max, min, pow, sqrt, etc... ---> methods
PI ----> Field, attribute, variable

Math.PI 
Math.cos(Math.PI / 2); // 0.0

- Format the value: DecimalFormat (java.text)
String format
"-0.268"
1 + "" ---> "1"

Double.parseDouble("0.23"); // 0.23
Integer.parseInt("12"); // 12

- Wrapper classes
byte ---> Byte
short ---> Short
int ---> Integer
long ---> Long

float ---> Float
double ---> Double

char ---> Character
boolean ---> Boolean

All wrapper classes are part of java.lang

Double.parseDouble("23.5F"); // Invalid ---> Run-time error

int val = 12;
Integer valObj = new Integer(val);

valObj.doubleValue(); // 12.0

Autoboxing: 
Integer valObj = 12; // <=> new Integer(12)
int val = valObj; // Unboxing
---------------------------------------------------End of Chapter 3

Chapter 4: Write Classes

Example: 
Die.java ---> Helper class
Main.java ---> Driver class

CRUD (Create, Read, Update, Delete) 
API (Application Programming Interface) endpoints

length method of String: 
int length()

nextLine of the Scanner:
String nextLine()



















