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(i'm sry if i make english mistake my native language is french) for a university project i've to make a little software, the user need to inmput a number, it's why i used a JFormattedTextField, but i also need to allow an empty field and i don't know how to do it, if someone is kind enought to help me i would be more than happy.

the code that i use:

    NumberFormat format = NumberFormat.getInstance();
    NumberFormatter formatter = new NumberFormatter(format);
    formatter.setValueClass(Integer.class);
    formatter.setAllowsInvalid(false);
    formatter.setCommitsOnValidEdit(true);
    textID = new JFormattedTextField(formatter);

I find this here JFormattedTextField problem 

final JFormattedTextField field = new JFormattedTextField(NumberFormat.getInstance()) {
@Override
protected void processFocusEvent(final FocusEvent e) {
    if (e.isTemporary()) {
        return;
    }

    if (e.getID() == FocusEvent.FOCUS_LOST) {
        if (getText() == null || getText().isEmpty()) {
            setValue(null);
        }
    }
    super.processFocusEvent(e);
}};

but i don't know to use it so i try to create my own version with my knowledge in class

class JFormattedTextFieldCorrected extends JFormattedTextField{
public JFormattedTextFieldCorrected(NumberFormatter formatter) {
    super(formatter);
}

@Override
protected void processFocusEvent(final FocusEvent e) {
    if (e.isTemporary()) {
        return;
    }

    if (e.getID() == FocusEvent.FOCUS_LOST) {
        if (getText() == null || getText().isEmpty()) {
            setValue(null);
        }
    }
    super.processFocusEvent(e);
}}

of course i changed JFormattedTextField by JFormattedTextFieldCorrected but i didn't manage to make it work. Have a nice day.

[edit this is a minimal reproductible exemple, to use it just enter a random number and try to erase it]

import java.text.NumberFormat;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.text.NumberFormatter;

public class MinimalExempleTextFormat extends JFrame{
    private JFormattedTextField textID;
    public MinimalExempleTextFormat() {
        NumberFormat format = NumberFormat.getInstance();
        NumberFormatter formatter = new NumberFormatter(format);
        formatter.setValueClass(Integer.class);
        formatter.setAllowsInvalid(false);
        formatter.setCommitsOnValidEdit(true);
        getContentPane().setLayout(null);
        textID = new JFormattedTextField(formatter);
        textID.setBounds(208, 0, 226, 261);
        getContentPane().add(textID);
        this.setSize(500,500);
    }
    public static void main(String[] args) {
        MinimalExempleTextFormat m=new MinimalExempleTextFormat();
        m.setVisible(true);
    }
}

[edit i find a way to avoid this problem]

Kaput
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    Please clarify your question. JFormattedTextField supports by default `null` as value (in this case you'll see an empty text field). Please also provide a [mcve] so we can also reproduce your problem. – Sergiy Medvynskyy Dec 19 '21 at 17:19
  • Myself, I'd just use a JTextField and give its Document a DocumentFilter that allows numbers or an empty field. – Hovercraft Full Of Eels Dec 19 '21 at 17:29
  • My answer [here](https://stackoverflow.com/a/11093360/522444) would work, but you'd have to simply modify the test method to allow an empty String. – Hovercraft Full Of Eels Dec 19 '21 at 18:14

0 Answers0