Primitive vs Reference types

Primitive types (기본형)

• The variable contains the value itself
• what are they
  • byte
  • short
  • int
  • long
  • float
  • double
  • char
  • boolean

// 변수 선언 variable declaration
int a; // type variableName;

• camelCase recommended

// primitive types
int myInt = 123;
long myLong = 12343245325L; // add L (or l)
float myFloat = 3.14f; // add f
double myDouble = 3.143252;
boolean myBoolean = true;
 
char a1 = 'a';
char a2 = 97;
 
// class
String myString = "hello";

• String is actually a class
  • the myString variable is now the String class’s instance

Reference type (참조형)

• The variable points to where the value is stored
• null can only be stored in reference types!
  • the default value of a reference type is null
• types
  • objects
  • String
  • int[]

Person p1, p2;
p1 = new Person("Leejun", 23);
p2 = p1;
p2.setName("Kirby") // p1 name's will change too!

• p1 and p2 points to the same person instance