[Java] 명품 자바 프로그래밍(Java Programming) 5장 실습문제 2번

Calc.java

 

package ch05;
 
public abstract class Calc {
    protected int a;
    protected int b;
 
    public abstract void setValue(int a, int b);
 
    public abstract int calculate();
}
 
 

Add.java

 

 
package ch05;
 
public class Add extends Calc {
 
    public void setValue(int a, int b) {
        this.a = a;
        this.b = b;
    }
 
    public int calculate() {
        return a + b;
    }
 
}
 

Sub.java

 

 
package ch05;
 
public class Sub extends Calc {
 
    public void setValue(int a, int b) {
        this.a = a;
        this.b = b;
    }
 
    public int calculate() {
        return a - b;
    }
 
}
 

Mul.java

 

 
package ch05;
 
public class Mul extends Calc {
 
    public void setValue(int a, int b) {
        this.a = a;
        this.b = b;
    }
 
    public int calculate() {
        return a * b;
    }
 
}
 

Div.java

 

package ch05;
 
public class Div extends Calc {
 
    public void setValue(int a, int b) {
        this.a = a;
        this.b = b;
    }
 
    public int calculate() {
        return a / b;
    }
 
}
 

Practice02.java

 

 
package ch05;
 
import java.util.Scanner;
 
public class Practice02 {
 
    @SuppressWarnings("resource")
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        Calc calculator = null;
 
        int a = 0;
        int b = 0;
 
        String operator = "";
 
        System.out.print("두 정수와 연산자를 입력하시오 >> ");
 
        a = scan.nextInt();
        b = scan.nextInt();
        operator = scan.next();
 
        switch (operator) {
        case "+":
            calculator = new Add();
            break;
 
        case "-":
            calculator = new Sub();
            break;
 
        case "*":
            calculator = new Mul();
            break;
 
        case "/":
            calculator = new Div();
            break;
        }
 
        calculator.setValue(a, b);
        System.out.println(calculator.calculate());
    }
 
}
 

실행 결과: