java - Where should scanner go in this program? -

i'm working on program takes input of 2 numbers , different calculations. have twonumbers class several different methods calculate sum, distance, average, etc.

should put scanner in class, or should put in main method?

i know basic i've been learning java couple weeks , i'm having hard time finding how should done/how input correlate instance variables , firstnumber , secondnumber

public class twonumbers{  private double firstnumber; private double secondnumber;  public double getsum() {     double sum = firstnumber + secondnumber;     return sum; }  public double getdifference() {     double difference = firstnumber - secondnumber;     return difference; }  public double getproduct() {     double product = firstnumber - secondnumber;     return product; }  public double getaverage() {     double average = (firstnumber + secondnumber) / 2;     return average; }  public double getdistance() {     double distance = math.abs(firstnumber - secondnumber);     return distance; }  public double getmax() {     double maximum = math.max(firstnumber, secondnumber);     return maximum; }  public double getmin() {     double minimum = math.min(firstnumber, secondnumber);     return minimum; } } 

each class should follow single responsibility principle. twonumbers class should work double numbers , perform operations on them, nothing more. providing double numbers class should in client, , ability provide numbers, means client may define scanner or way provide data.