Java Program to develop a Calculator

import java.io.*;
import java.util.*;
public class Calculator{
    Scanner scan=new Scanner(System.in);
    int a, b, z;
    char sign;
    String str;
    public void input(){
        try{
            System.out.print("Enter the expression:- ");
            a=scan.nextInt();
            str=scan.next();
            sign=str.charAt(0);
            b=scan.nextInt();
        }
        catch(Exception e){
            System.out.println("Following Error occured while processing: "+e);
            System.exit(0);
        }
    }

    public void compute(){
        switch(sign){
            case '+': z=a+b; System.out.println(a+" "+sign+" "+b+"= "+z); break;
            case '-': z=a-b; System.out.println(a+" "+sign+" "+b+"= "+z); break;
            case '*': z=a*b; System.out.println(a+" "+sign+" "+b+"= "+z); break;
            case '/': z=a/b; System.out.println(a+" "+sign+" "+b+"= "+z); break;
            case '%': z=a%b; System.out.println(a+" "+sign+" "+b+"= "+z); break;
            default: System.out.println("Following Error Occured: Wrong Operator used!");
        }
    }

    public static void main(String[] args){
        Calculator obj=new Calculator();
        obj.input();
        obj.compute();
    }
}