JAVA1_day18 | 생성자 Constructor 연습문제

1. Tv 클래스

package constructorex;
 
class Tv {
    String brand;
    int year;
    int size;
    
    public Tv() {}
    
    Tv(String brand, int year, int size) {
        this.brand = brand;
        this.year = year;
        this.size = size;
    }
    
    void show() {
        System.out.print(brand + "에서 만든 ");
        System.out.print(year + "년 ");
        System.out.print(size + "인치 TV");
    }
}
 
public class ConTest04 {
    public static void main(String[] args) {
 
        Tv myTv = new Tv("LG", 2018, 65);
        myTv.show();
        
    }
}

2. Book 클래스

package constructorex;
 
class Book {
    String title;
    String author;
 
    public Book() {}
    
    Book(String title) {
        this(title, "작자 미상");
    }
    
    Book(String title, String author) {
        this.title = title;
        this.author = author;
    }
}
 
public class ConTest05 {
    public static void main(String[] args) {
 
        Book littlePrince = new Book("어린왕자", "생텍쥐페리");
        Book loveStory = new Book("춘향전");
        
        System.out.println(littlePrince.title + " " + littlePrince.author);
        System.out.println(loveStory.title + " " + loveStory.author);
        
    }
}

3. Song 클래스

package constructorex;
 
class Song {
    String title;
    String singer;
    int year;
    String country;
    
    public Song() {}
    
    Song(String title, String singer, int year, String country) {
        this.title = title;
        this.singer = singer;
        this.year = year;
        this.country = country;
    }
    
    void show() {
        System.out.print(year + "년 ");
        System.out.print(country + " 국적의 ");
        System.out.print(singer + "가 부른 ");
        System.out.print(title);
    }
}
 
public class ConTest06 {
    public static void main(String[] args) {
 
        Song myFavorite = new Song("Dancing Queen", "ABBA", 1978, "스웨덴");
        myFavorite.show();
        
    }
}

4. Grade 클래스 

package constructorex;
 
import java.util.Scanner;
 
class Grade {
    int math;
    int science;
    int english;
    double average;
    
    public Grade() {}
    
    Grade(int math, int science, int english) {
        this.math = math;
        this.science = science;
        this.english = english;
    }
    
    String average() {
        average = (math + science + english) / 3.0;
        return String.format("%.1f", average);
    }
}
 
public class ConTest07 {
    public static void main(String[] args) {
 
        Scanner sc = new Scanner(System.in);
        
        System.out.print("수학점수 입력: ");
        int math = sc.nextInt();
 
        System.out.print("과학점수 입력: ");
        int science = sc.nextInt();
        
        System.out.print("영어점수 입력: ");
        int english = sc.nextInt();
        
        Grade hgd = new Grade(math, science, english);
        System.out.println("평균은 " + hgd.average());
        
        sc.close();
        
    }
}

5. Circle 클래스

package constructorex;
 
// 객체 배열 
class Circle {
    int radius;
    
    public Circle() {}
    
    Circle(int radius) {
        this.radius = radius;
    }
    
    double getArea() {
        return 3.14 * radius * radius;
    }
}
 
public class ConTest08 {
    public static void main(String[] args) {
        
        Circle c1 = new Circle(0);
        Circle c2 = new Circle(1);
        Circle c3 = new Circle(2);
        Circle c4 = new Circle(3);
        Circle c5 = new Circle(4);
        
        System.out.println("c1의 면적: " + c1.getArea());
        System.out.println("c2의 면적: " + c2.getArea());
        System.out.println("c3의 면적: " + c3.getArea());
        System.out.println("c4의 면적: " + c4.getArea());
        System.out.println("c5의 면적: " + c5.getArea());
        
    }
}

6. Cir (Circle2) 클래스

package constructorex;
 
class Cir {
    int radius;
 
    public Cir() {}
 
    Cir(int radius) {
        this.radius = radius;
    }
 
    double getArea() {
        return 3.14 * radius * radius;
    }
}
 
public class ConTest09 {
    public static void main(String[] args) {
 
        int[] arr = new int[5];
        Cir[] myCir = new Cir[5];
 
        // c[0] = new Cir(0);
        // c[1] = new Cir(1);
        // c[2] = new Cir(2);
        // c[3] = new Cir(3);
        // c[4] = new Cir(4);
 
        for (int i=0; i<myCir.length; i++) {
            myCir[i] = new Cir(i);
        }
        
        for (int i=0; i<myCir.length; i++) {
            System.out.println("myCir[" + i + "]: " + myCir[i].getArea());
        }
    }
}

7. Book (Booking) 클래스

package constructorex;
 
import java.util.Scanner;
 
class Booking {
    String title;
    String author;
    
    Booking() {}
    
    Booking(String title, String author) {
        this.title = title;
        this.author = author;
    }
    
    void show() {
        System.out.println("책 이름: " + title + " / 저자: " + author);
    }
}
 
public class ConTest10 {
    public static void main(String[] args) {
 
        Booking[] myBook = new Booking[3];
        
        Scanner sc = new Scanner(System.in);
        
        for (int i=0; i<myBook.length; i++) {
            System.out.print((i+1) + ". 책의 이름을 입력하세요: ");
            String title = sc.nextLine();
            System.out.print((i+1) + ". 책의 저자를 입력하세요: ");
            String author = sc.nextLine();
            myBook[i] = new Booking(title, author);
        }
        
        for (int i=0; i<myBook.length; i++) {
            myBook[i].show();
        }
        
    }
}

8. Phone 클래스 

package constructorex;
 
import java.util.Scanner;
 
class Phone {
    String name;
    int number;
    
    public Phone() {}
    
    Phone(String name, int number) {
        this.name = name;
        this.number = number;
    }
}
 
public class ConTest11 {
    public static void main(String[] args) {
 
        Scanner sc = new Scanner(System.in);
        System.out.print("저장할 인원 수를 입력하세요: ");
        int userNum = sc.nextInt();
        
        Phone[] myPhone = new Phone[userNum];
        
        for(int i=0; i<myPhone.length; i++) {
            System.out.print((i + 1) + ". 이름을 입력하세요: ");
            String name = sc.next();
            System.out.print((i + 1) + ". 전화번호를 입력하세요: ");
            int number = sc.nextInt();
            myPhone[i] = new Phone(name, number);
        }
        
        System.out.println("저장을 완료하였습니다.");
 
        while (true) {
            System.out.print("검색할 이름을 입력하세요: ");
            String search = sc.next();
            
            for (int i = 0; i < myPhone.length; i++) {
                if (search.equals(myPhone[i].name)) {
                    System.out.println(myPhone[i].name + "의 전화번호: " + myPhone[i].number);
                } 
            }
            
            if (search.equals("stop")) {
                break;
            }
        } // while
        
    }
}