Why does it return default?

Question

Java

import java.util.Scanner;
public class TestConditions {

  public static void main(String[] args) {
    Conditions cond = new Conditions();
    try (Scanner scanner = new Scanner(System.in)) {
      System.out.println("Введите первое число:");
      cond.setFirstChange(scanner.nextInt());
      System.out.println("Введите второе число:");
      cond.setSecondChange(scanner.nextInt());
      System.out.println("Введите номер операции: 1.Умножение 2.Деление 3.Сложение");
      cond.setThirdChange(scanner.nextInt());
      cond.operation(cond.getFirstChange(), cond.getSecondChange(), cond.getThirdChange());
    }
  }
}


public class Conditions {
      private int firstChange;
    private int secondChange;
    private int thirdChange;
  
  
    public void setFirstChange(int a){
      a = firstChange;
    }
    public void setSecondChange(int b){
      b = secondChange;
    }	
    public void setThirdChange(int c){
      c = thirdChange;
    }
    
    public int getFirstChange(){
      return firstChange;
    }
    public int getSecondChange(){
      return secondChange;
    }	
    public int getThirdChange(){
      return thirdChange;
    }
      public void operation(int x, int y, int z) {
        switch(z) {
        case 1:
          int res = x*y;
          System.out.println(res);
          break;
        case 2:
          int res1 = x/y;
          System.out.println(res1);
          break;
        case 3:
          int res2 = x+y;
          System.out.println(res2);
          break;
        default:
          System.out.println("Операция не определена");
        }
        
      }
      
}

Returns "Operation not defined". I can't figure out what's wrong?
PS If the question is very stupid, then I apologize in advance, I'm just starting to learn Java.

Answer 1

1. The text must be formatted.
2. In the setters of the Conditions class, you must assign the value of the parameter to the fields, and not vice versa.