'9' ---> 9
Integer.parseInt('9' + ""); // 9
'9' - '0' = 9

Wrapper classes: 
There are 8 wrapper classes

Double.parseDouble("23.5"); 
parseDouble is static --> It can be used through the class name, namely Double
Double.parseDouble("23F"); // run-time error

Integer.parseInt("23"); // 23

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

valObj.doubleValue(); // 12.0
Integer.MIN_VALUE
Integer.MAX_VALUE

Autoboxing vs unboxing: 

Integer valObj = 12; // <=> new Integer(12) made possible by Autoboxing
// int val = valObj.intValue();
int val = valObj; // Unboxing
-------------------------------------End of Chapter 3 material

Chapter 4: Writing Classes

API endpoints (CRUD)
API - Application Programming Interface

Example#1: 
Die.java - Helper class
Main.java - Driver class

length of String:
int length()

nextLine() of Scanner:
String nextLine()

nextInt(upper) of Random:
int nextInt(int upper)

"One code a day will keep the doctor away" - COE 211























