실습 문제 1: 학생 정보 관리하기

public class Main {
    public static void main(String[] args) {
        Student gilDong = new Student("홍길동", 16, "1학년");
        System.out.println(gilDong);
    }
}

public class Student {
    private String name;
    private int age;
    private String grade;

    public Student(String name, int age, String grade) {
        this.name = name;
        this.age = age;
        this.grade = grade;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\\'' +
                ", age=" + age +
                ", grade='" + grade + '\\'' +
                '}';
    }
}

실습 문제 2: TV 기능 구현하기

public class Main {
    public static void main(String[] args) {
        TV tv = new TV();
        tv.togglePower();
        tv.changeChannel(5);

        System.out.println(tv);
    }
}

public class TV {
    private boolean power = false;
    private int channel;

    public void togglePower() {
        power = !power;
    }

    public void changeChannel(int channel) {
        this.channel = channel;
    }

    @Override
    public String toString() {
        return "TV{" +
                "power=" + power +
                ", channel=" + channel +
                '}';
    }
}

실습 문제 3: 간단한 계산기 만들기

public class Main {
    public static void main(String[] args) {
        Calculator calculator = new Calculator();

        System.out.println("더하기 결과: " + (int) calculator.add(10, 5));
        System.out.println("빼기 결과: " + (int) calculator.subtract(10, 5));
        System.out.println("곱하기 결과: " + (int) calculator.subtract(10, 5));
        System.out.println("나누기 결과: " + (int) calculator.subtract(10, 5));
    }
}

public class Calculator {
    private String modelNumber;

    public String getSystemInfo() {
        return modelNumber;
    }

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

    public double subtract(double a, double b) {
        return a - b;
    }

    public double divide(double a, double b) {
        return a / b;
    }

    public double multiply(double a, double b) {
        return a * b;
    }
}

실습 문제 4: 동물 클래스 정의하기

public class Main {
    public static void main(String[] args) {
        Animal dog = new Animal("뽀삐", "개");
        Animal cat = new Animal("나비", "고양이");
        Animal hamster = new Animal("찡찡이", "햄스터");

        System.out.println(dog);
        System.out.println(cat);
        System.out.println(hamster);
    }
}

public class Animal {
    private String name;
    private String type;

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

    @Override
    public String toString() {
        return "이름: " + name + ", 종류: " + type;
    }
}