JFormattedTextField

 

✅ Java Swing JFormattedTextField – Overview & Usage

JFormattedTextField is a Swing component that restricts input to a specific format such as numbers, dates, currency, phone numbers, etc.

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🔧 Key Features

Feature	Description
setValue(Object)	Set initial/formatted value
getValue()	Get current formatted value
setFormatterFactory(...)	Set a custom formatter like number, date, etc.
Supports masks	Input masks (e.g., for phone numbers)
Formatting on focus lost	Value becomes formatted when user leaves the field

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✅ Common Use Cases with Examples

1. Number Format

import javax.swing.*;
import java.text.NumberFormat;

public class NumberFormattedField {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Number Format");
        frame.setSize(300, 100);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        NumberFormat numberFormat = NumberFormat.getNumberInstance();
        JFormattedTextField numberField = new JFormattedTextField(numberFormat);
        numberField.setValue(1234.56);  // default value

        frame.add(numberField);
        frame.setVisible(true);
    }
}

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2. Date Format

import javax.swing.*;
import java.text.DateFormat;

public class DateFormattedField {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Date Format");
        frame.setSize(300, 100);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.SHORT);
        JFormattedTextField dateField = new JFormattedTextField(dateFormat);
        dateField.setValue(new java.util.Date());

        frame.add(dateField);
        frame.setVisible(true);
    }
}

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3. Mask Formatter (Phone Number)

import javax.swing.*;
import javax.swing.text.MaskFormatter;
import java.text.ParseException;

public class MaskFormatField {
    public static void main(String[] args) throws ParseException {
        JFrame frame = new JFrame("Phone Number");
        frame.setSize(300, 100);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        MaskFormatter phoneFormat = new MaskFormatter("(###)-###-####");
        JFormattedTextField phoneField = new JFormattedTextField(phoneFormat);

        frame.add(phoneField);
        frame.setVisible(true);
    }
}

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🔁 Getting & Setting Values

Object val = formattedTextField.getValue();  // Get value
formattedTextField.setValue("123");         // Set value

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🧠 Tips

• Use setFocusLostBehavior(JFormattedTextField.COMMIT) to ensure formatting on focus lost.

• You can use getText() for raw string, but getValue() is preferred for formatted data types.

Would you like an example combining this with JButton to validate and show the input?