Object Oriented Programming

Java Virtual Machine

Garbage Collection

Java Collections Framework

IS-A, HAS-A

equals와 hashCode

Overriding & Overloading

Wrapper class (AutoBoxing & AutoUnBoxing)

Multi-Thread

Promotion & Casting (업캐스팅 & 다운캐스팅)

String & StringBuffer & StringBuilder

static

inner class & inner static class 차이점

Abstract Class

Enum Class

Call by value & Call by reference

Shallow copy & Deep copy

Serializable

if 조건문 (&&, ||)