클래스와 객체

Java 프로그래밍 - 클래스와 객체_1

class Car {
    String name;
    String type;

    public void printCarInfo() {
        System.out.println("=== Car Info ===");
        System.out.println("name: " + name);
        System.out.println("type: " + type);
    }

    public void move() {
        System.out.println("이동!");
    }

    public void brake() {
        System.out.println("정지!");
    }
}

class Car2 {
    String name;
    String type;

//    Car2() {}
    Car2(String name, String type) {
        this.name = name;
        this.type = type;
        System.out.println("생성자 출력!");
    }

    public void printCarInfo() {
        System.out.println("=== Car Info ===");
        System.out.println("name: " + name);
        System.out.println("type: " + type);
    }

    public void load() {
        System.out.println("짐을 주세요!");
    }

    public void horn() {
        System.out.println("빵빵!");
    }
}


public class Main {

    public static void main(String[] args) {
        Car myCar1 = new Car();
        myCar1.name = "a";
        myCar1.type = "suv";
        myCar1.printCarInfo();
        myCar1.move();
        myCar1.brake();

        Car2 myCar2 = new Car2("b", "sedan");
        myCar2.printCarInfo();
        myCar2.load();
        myCar2.horn();
    }
}

=== Car Info ===
name: a
type: suv
이동!
정지!
생성자 출력!
=== Car Info ===
name: b
type: sedan
짐을 주세요!
빵빵!

//  Practice
//  다음 클래스 직접 만든 후 객체 생성
//  클래스명: Animal
//  특성: 이름, 무게, 분류
//  기능: 먹기, 잠자기, 걷기, 뛰기

class Animal {
    String name;
    Double weight;
    String classification;

    Animal(String name, Double weight, String classification) {
        this.name = name;
        this.weight = weight;
        this.classification = classification;
    }

    public void printInfo() {
        System.out.println("name = " + name);
        System.out.println("weight = " + weight);
        System.out.println("classification = " + classification);
    }

    public void eat() {
        System.out.println("냠냠!");
    }

    public void sleep() {
        System.out.println("쿨쿨!");
    }

    public void walk() {
        System.out.println("걷기!");
    }

    public void run() {
        System.out.println("뛰기!");
    }
}


public class Practice {
    public static void main(String[] args) {
        // Test code
        Animal animal1 = new Animal("강아지", 5.0, "포유류");
        Animal animal2 = new Animal("구피", 0.01, "어류");

        animal1.printInfo();
        animal2.printInfo();
    }
}

name = 강아지
weight = 5.0
classification = 포유류
name = 구피
weight = 0.01
classification = 어류

Java 프로그래밍 - 클래스와 객체_2

package car;

public class Car2 {
    public String name1;
    public String name2;
    public String name3;
    public String name4;

    public Car2(String name1, String name2, String name3, String name4) {
        this.name1 = name1;
        this.name2 = name2;
        this.name3 = name3;
        this.name4 = name4;
    }

}

import car.Car2;

class Car {
    String name;
    String type;

    Car(String name, String type) {
        this.name = name;
        this.type = type;
    }

    public void printCarInfo() {
        System.out.println("=== Car Info ===");
        System.out.println("name: " + name);
        System.out.println("type: " + type);
    }

    public void printCarInfo(String date) {
        printCarInfo();
        System.out.println("date: " + date);
    }

    public void printCarInfo(int number) {
        printCarInfo();
        System.out.println("number: " + number);
    }

    public void printCarInfo(String date, int number) {
        printCarInfo();
        System.out.println("date: " + date);
        System.out.println("number: " + number);
    }

}


class Car3 {
    static String name = "None";
    String type;

    Car3(String name, String type) {
        this.name = name;
        this.type = type;
    }

    public void printCarInfo() {
        System.out.println("=== Car Info ===");
        System.out.println("name: " + name);
        System.out.println("type: " + type);
    }

    public static void getName() {
        System.out.println("Car name: " + name);
//        System.out.println("Car type: " + type);
    }
}


public class Main {

    public static void main(String[] args) {
        Car myCar1 = new Car("a", "sedan");
        myCar1.printCarInfo();

//      1. 오버로딩
        myCar1.printCarInfo("2022");
        myCar1.printCarInfo(1);
        myCar1.printCarInfo("2022", 1);


//      2. 접근 제어자
        System.out.println("=== 접근 제어자 ===");
        Car2 myCar2 = new Car2("a", "b", "c", "d");
        System.out.println("name1: " + myCar2.name1);
        System.out.println("name2: " + myCar2.name2);
        System.out.println("name3: " + myCar2.name3);
        System.out.println("name4: " + myCar2.name4);


//      3. Static
        System.out.println("=== Static ===");
        Car3.getName();
        Car3 myCar3_1 = new Car3("a", "sedan");
        Car3 myCar3_2 = new Car3("b", "suv");
        Car3 myCar3_3 = new Car3("c", "rv");
        myCar3_1.printCarInfo();
        myCar3_2.printCarInfo();
        myCar3_3.printCarInfo();

        Car3.getName();
        
    }

}

=== Car Info ===
name: a
type: sedan
=== Car Info ===
name: a
type: sedan
date: 2022
=== Car Info ===
name: a
type: sedan
number: 1
=== Car Info ===
name: a
type: sedan
date: 2022
number: 1
=== 접근 제어자 ===
name1: a
name2: b
name3: c
name4: d
=== Static ===
Car name: None
=== Car Info ===
name: c
type: sedan
=== Car Info ===
name: c
type: suv
=== Car Info ===
name: c
type: rv
Car name: c

// Practice
// 오버로딩

class Calculator {

    public int sum(int a, int b) {
        return a + b;
    }

    public double sum(double a, double b) {
        return a + b;
    }

    public double sum(String a, String b) {
        return Double.parseDouble(a) + Double.parseDouble(b);
    }

    public int sum(int a, int b, int c) {
        return a + b + c;
    }
}

public class Practice {
    public static void main(String[] args) {
        // Test code
        Calculator c = new Calculator();
        System.out.println(c.sum(1, 2));
        System.out.println(c.sum(1.0, 2.0));
        System.out.println(c.sum("1", "2"));
        System.out.println(c.sum(1, 2, 3));
    }
}

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3.0
3.0
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