is it possible to permanently change the value of a double variable by using an if statement?

[Liam Rice]

is it possible to permanently change the value of a double variable by using an if statement? here is the code i have so far but it doesn't work. Any help please?

public class Admin extends javax.swing.JFrame {
double EURtoGBP = 0.8482;
private void btnSaveActionPerformed(java.awt.event.ActionEvent evt) {                                        
       Object getEuroRequest = cmbEuro.getSelectedItem();
       String getEuroInput = getEuroRequest.toString();
       String gotEuroRequest = getEuroInput.substring(6);
       
       //if(gotEuroRequest == "GBP"){
       if(cmbEuro.getSelectedItem().equals("EURtoGBP")){
           double reqEuro = Double.parseDouble(changeEuro.getText());
           EURtoGBP = reqEuro;
       }

thank you

[Dave Tolls]

What do you mean by "it doesn't work"?
What result are you getting and what result are you expecting?

[Liam Rice]

 

Dave Tolls wrote:What do you mean by "it doesn't work"?
What result are you getting and what result are you expecting?

well i want double EURtoGBP = 0.8482; to change to whatever the user inputs into changeEuro text field

[Dave Tolls]

OK.
I suggest adding some logging in there, println() calls would do, to log what the value of everything is, and what path through that bit of code it takes.

[Henry Wong]

 

Liam Rice wrote:
well i want double EURtoGBP = 0.8482; to change to whatever the user inputs into changeEuro text field

From the code (ie. name of the method), I am going to speculate that there is a save button somewhere in the application. And that code that reads and sets the field is only executed when the button is pressed.... If I am wrong regarding this, then never mind ...

Anyway, you can place action listeners on text fields, so you can execute code, and hence, change variables, as soon as the user changes the fields. You still need to check it to make sure that the field is valid (and not blank), but this should not depend on the user pressing a button.

Henry

[Liam Rice]

 

Henry Wong wrote:

Liam Rice wrote:
well i want double EURtoGBP = 0.8482; to change to whatever the user inputs into changeEuro text field

From the code (ie. name of the method), I am going to speculate that there is a save button somewhere in the application. And that code that reads and sets the field is only executed when the button is pressed.... If I am wrong regarding this, then never mind ...

Anyway, you can place action listeners on text fields, so you can execute code, and hence, change variables, as soon as the user changes the fields. You still need to check it to make sure that the field is valid (and not blank), but this should not depend on the user pressing a button.

Henry

yes, this part of the program is for the admin to go to to change the exchange rate that the actual application uses within the calculation (to update). The user selects an exchange rate that they want to change, e.g. GBPtoUSD and they put in the updated exchange rate and then press save. At this point i am then wanting the user input to replace the GBPtoUSD once the save button is clicked

[Knute Snortum]

If you have started the program in a way that you can see output to the command line (or a command box if in an IDE), put some debugging lines in the code, like:

public class Admin extends javax.swing.JFrame {
double EURtoGBP = 0.8482;
private void btnSaveActionPerformed(java.awt.event.ActionEvent evt) {
System.out.println("In btnSaveActionPerformed");  // debug                                    
   Object getEuroRequest = cmbEuro.getSelectedItem();
   String getEuroInput = getEuroRequest.toString();
   String gotEuroRequest = getEuroInput.substring(6);
   
   //if(gotEuroRequest == "GBP"){
   if(cmbEuro.getSelectedItem().equals("EURtoGBP")){
    System.out.println("Selected item is EURtoGBP"); // debug
       double reqEuro = Double.parseDouble(changeEuro.getText());
       EURtoGBP = reqEuro;
       System.out.println("Set EURtoGBP to " + reqEuro); // debug
   }
}

Putting "// debug" after each line will help you find and remove the debugging lines after you don't need them.

[Dave Tolls]

I'd add one before the 'if' statement as well:

System.out.println("Selected item is " + cmbEuro.getSelectedItem()); // debug