✅ Abstract class Parent class, but can NOT be created as instance 동물이라는 개념 안에 강아지, 고양이 등이 있지만 "동물"이라고 하는 동물은 없음 따라서 동물은 인스턴스를 생성하면 안 됨 Animal class: abstract class Dog class, Ca...

⭐️ extends ⭐️ method overriding ✅ Polymorphism: parent can become child parent class child class extends parent class 1️⃣ Polymorphism: parent CAN become child instance child CAN N...

✅ Final final: can not change after initialization final value can not be altered after initializatoin 처음 값 할당 후에는 변수의 값을 변경하지 못하게 막아버린다 👎🏻 without final int data0; data0 = 10; ...

✅ Extends if extends, extends the field and method of parent class public class Car { public void move(){} } public class GasCar extends Car{ public void fillGas(){} } public class...

✅ Method, Stack, Heap ✔️ Method class ✔️ Stack methods program is run ✔️ Heap Instance created new class instance, array 💡 Method shared data to run program class...

✅ What does access modifier do? Allow access or hide class, field, constructor, method from outside class/package Developer should not change speaker volume outside speaker class ...

✅ this this refers to the field of the current class this is to distinguish which is field and which is paramter when the variable names are the same this.name: the name field of th...

Procedural Oridented 🆚 Object oriented Procedural Oridented: 순서 중요, how, 메소드 분리 Object oriented: 객체, what, 객체안에 메소드 포함 ✅ example of procedural programming example of Music Player ...

✅ Primitive type int, long, double, boolean save value itself int A = 10; ✅ Reference type class is reference type String save memory value Student student = new Student(); stud...

✅ Why do we need class? collect each student’s charecteristics in one class create one student class and save one student’s name, age, grade in one class there is int type, String...