JavaFX Scene Builder Tutorial 34: Calculator

JavaFX Scene Builder Tutorial 34 Calculator JavaFX

Code source here : https://codebyamir.blogspot.com/

@FXML
private TextField txt_result;
String op ="";
long number1;
long number2;
// First Method
public void Number (ActionEvent ae){
String no = ((Button)ae.getSource()).getText();
txt_result.setText(txt_result.getText()+no);
}

// Second Method
public void Operation (ActionEvent ae){

String operation = ((Button)ae.getSource()).getText();
if (!operation.equals("=")){
if(!op.equals("")){
return;
}
op = operation;
number1 = Long.parseLong(txt_result.getText());
txt_result.setText("");
}else {
if(op.equals("")){
return;
}
number2 = Long.parseLong(txt_result.getText());
calculate(number1, number2, op);
op="";
}
}
// 3 Methode
public void calculate (long n1, long n2, String op){

switch (op){

case "+" : txt_result.setText(n1 + n2 + "");break;
case "-" : txt_result.setText(n1 - n2 + "");break;
case "*" : txt_result.setText(n1 * n2 + "");break;
case "/" :
if (n2 == 0){
txt_result.setText("0");break;
}
txt_result.setText(n1/n2+ "");break;
}
}
Libraries Importing :
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;