import java.text.NumberFormat;

import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.text.NumberFormatter;

public class NumberTextFieldExample {

    public NumberTextFieldExample(){
        init(); 
    }
    
    private void init() {
        NumberFormat format = NumberFormat.getInstance();
        format.setGroupingUsed(false);
        NumberFormatter formatter = new NumberFormatter(format);
        formatter.setAllowsInvalid(false);
        JFormattedTextField field = new JFormattedTextField(formatter);
        
        JFrame frame = new JFrame("Zahlen-Textfeld");
        frame.add(field);
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
    
    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> new NumberTextFieldExample());
    }
}