Object oriented, Procedural Oridented, Encapsulation

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
  

• ✔️ music player class

public class MusicPlayerData {
    int volume;
    boolean isOn;
}

• ✔️ class with method

public class MusicPlayerMain {
    public static void main(String[] args) {
        MusicPlayerData data = new MusicPlayerData();

        turnOn(data);
        raiseVolume(data);
    }

    static void turnOn(MusicPlayerData data){
        data.isOn = true;
        System.out.println("music player is on");
    }

    static void raiseVolume(MusicPlayerData data){
        data.volume++;
        System.out.println("volume: " + data.volume);
    }

• more focused on the order (turn on, then raise volume)
• 👎🏻 music player field and method are in different classes
• one in music player class and other in main class
• field and method of music player are very very relevent
• can we find a way to put field and method in one class?

✅ change into OOP

• ✔️ music player class
• has both field and method

public class MusicPlayer {
    int volume; //field
    boolean isOn; //field

    void turnOn(){ //method
        isOn = true;
        System.out.println("music player is on");
    }

    void raiseVolume(){ //method
        volume++;
        System.out.println("volume: " + volume);
    }
}

• ✔️ main class
• only create instance, calls the method

public class MusicPlayerMain4 {
    public static void main(String[] args) {
        MusicPlayer player = new MusicPlayer();

        player.turnOn();
        player.raiseVolume();
    }
}

• more focused on how the music player works

• 👍🏻 field and method are in one class, easier for the programmer to understand
• 👍🏻 programming looks more like real life
• 👍🏻 easier to change code
  • only has to change music player class, main class does not change

✅ Encapsulation

• OOP에서처럼 field and method를 한 클래스에 캡슐로 감싸듯이 모은 것을 캡슐화라고 한다.
• 캡슐화: field and method를 묶어서 외부에 제공하는 것
• limit access with access modifiers