how to manipulate jtextfield return type?

Question

I have a jtext field

when user type a number like

123456789,10

it will automatic set in jtextfield

123,456,789.10

then if user click a button it will

System.out.print( the_same_number );

that will result

123456789.10

• how to do this?
• how to make jtextfield only accept input number and dot (.) and coma (,)?

(should i use formatted field in this case?)

thanks..

Answer 1

You will want to use a DocumentFilter to filter the input coming into the text field.

Check out MDP's Examples which actually has an example of the question you are asking

Answer 2

You can opt for the DocumentFilter as suggested by @MadProgrammer. However, it will be difficult to tackle the requirement to have a different display in the text field and when printing to console (it will require some extra manual parsing/formatting).

Combined with the requirement to accept only numbers I would strongly suggest to look at the JFormattedTextField in combination with a NumberFormat.

• The JFormattedTextField will only accept input that can be parsed by the NumberFormat (you can type invalid input, but it will never be accepted)
• The actual value (JFormattedTextField#getValue) will be a Double (if you choose the correct format), so you can print it perfectly

Note that the standard JFormattedTextField has some usability issues. With a bit of googling you can find different improved version of the JFormattedTextField. For example this one where I find the only missing thing is visual feedback when the input is invalid (e.g. make the background red)

Answer 3

"how to make jtextfield only accept input number and dot (.) and coma (,)?"

    @Override
    public void keyPressed(KeyEvent e) {
        int key = e.getKeyCode();
        if ((e.KeyChar >= 48 && e.KeyChar <= 57) || e.KeyChar == 46 || e.KeyChar == 44){
        }
        else{
        }
    }