JTextField's value disorientation on clearing

Question

I am trying to create a Java windows application using the WindowBuilder plug-in in Eclipse. I have a JTextField that works fine, on entry of the required values. But, when I clear all the contents on the field and try to re-enter other values, the values are disoriented i.e., the values don't appear at all, or seem to appear in the next line.

I'm using a DocumentListener, so yes, this might result in an empty string exception. But, I'm not sure why the contents of the JTextField are inappropriate on re-entry.

PFB my piece-of-code:

void computeTotal(final JTextField jtf){
    jtf.getDocument().addDocumentListener(new DocumentListener(){
        public void changedUpdate(DocumentEvent e) {
            //warn();
            getTotal();
        }
        public void removeUpdate(DocumentEvent e) {
            //warn();
            getTotal();
        }
        public void insertUpdate(DocumentEvent e) {
            //warn();
            getTotal();
        }
        public void getTotal(){
            bt = Float.parseFloat(billTotal.getText());
            bd = Float.parseFloat(billDeduction.getText()) ;
            ta = Float.parseFloat(taxAmt.getText());
            tt = bt - bd+ ta;
             totalTotal.setText(tt+"");
        }

    });
    }

What is the problem here?

Answer 1

What is the problem here?

• use JFormattedTextField formatted by Number Formatter, then is DocumentListener correct listener

• no parsing needed, no issue with nice output, thoushand separator, input of non number chars arenot allowed

• use DocumentFilter with Patern, there you can remove non number chars and then you can parse with quite save contens contains numbers, decimal separator and negative sing