Equivalent of PHP isset in JAVA

[africanhacker]

I have a GUI that takes a string in a text field. There some conversions (parse string to double) that happen the moment someone clicks the button. If nothing is in there exception exception, something I want to stop.

So I want something to check if the variable that receives this String has anything in it. Does stringVarible != null suffice?

[Petr]

It's a very difficult to understand that you want.
Do you want to check some parameters on not null, when you click on a button?

I don't advise you compare to Java and PHP. There are very difference language.

[africanhacker]

I want to make sure that something has been entered in a TextField when the button is pressed.

[Petr]

It's easy. You can make yourself listener for JButton. It would take a refer on JTextField object. In class a listener you will check a value from JTextField and if it's not null you will do something.

[africanhacker]

Thanks, some rep for you

[Petr]

it's good. if it's clear. I think you can show some short example. It will be a very useful for newbie, if they will have same question.

[JosAH]

It's easy. You can make yourself listener for JButton. It would take a refer on JTextField object. In class a listener you will check a value from JTextField and if it's not null you will do something.

The text String in a JTextField is never equal to null; at least it is the empty String "".

kind regards,

Jos

[Tolls]

If nothing is in there exception exception, something I want to stop.

It might have been an idea to actually tell us what the exception was...

[africanhacker]

JosAH you are quite right. I have just realised that !=null will not work. "" is the way to go with something like equalsIgnoreCase or something along those lines. At least that is what worked for me

[JosAH]

JosAH you are quite right. I have just realised that !=null will not work. "" is the way to go with something like equalsIgnoreCase or something along those lines. At least that is what worked for me

Or just do this:

if (field.getText().length() == 0)
   // no text in the field ...

kind regards,

Jos

[Tolls]

I'm still curious what the actual excpetion was...but maybe that's just me.

[Petr]

The other way you can use this String#isEmpty