Calclulator 핵심은 스캐너 겠지 .

import java.util.*;

class Calc
{
	public int a,b;
	
	public Calc(int a,int b){
		this.a=a;
		this.b=b;
	}

	public void option(String opt) 
	{
		if (opt.equals("+"))
		{
			this.plus();
		}
		else if (opt.equals("-"))
		{
			this.minus();
		}
		else if (opt.equals("/"))
		{
			this.nanum();
		}
		else if (opt.equals("*"))
		{
			this.gob();
		}
		else 
		{
		
		
		}
	}
		public void plus()
		{
			System.out.printf("더한 결과 :%d\n",this.a+this.b);
		}
		public void minus()
		{
			System.out.printf("뺀 결과 :%d\n",this.a-this.b);
		}
		public void nanum()
		{
			System.out.printf("나누기 결과 :%d\n",this.a/this.b);
		}
		public void gob()
		{
			System.out.printf("곱한 결과 :%d\n",this.a*this.b);
		}

	

}

class Calculator
{
	public static void main(String [] args){
		Scanner scan= new Scanner(System.in);
		System.out.println("숫자 1입력 해주세요");
		int a=scan.nextInt();
		System.out.println("숫자 2입력 해주세요");
		int b=scan.nextInt();
		System.out.println("연산자를 입력 해주세요");
		String c=scan.next();
		Calc jh=new Calc(a,b);
		jh.option(c);
	}
}