FocusEvent doesn't get the last value of JFormattedTextField, How I can get it?

Question

I have two JFormattedTextField objects on my JFrame object. I want a basic Math (addition) by the values of these JFormattedTextField

Answer 1

The default behavior of JFormattedTextField on focusLost is COMMIT_OR_REVERT, so one approach is to do the update after the focus listener has concluded. A continuation works nicely, as shown below.

import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.text.NumberFormat;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.JPanel;

/** @see http://stackoverflow.com/questions/6803976 */
public class Adder extends JPanel {

    private final NumberFormat format = NumberFormat.getNumberInstance();
    private final JFormattedTextField a = new JFormattedTextField(format);
    private final JFormattedTextField b = new JFormattedTextField(format);
    private final JFormattedTextField sum = new JFormattedTextField(format);

    public Adder() {
        this.setLayout(new GridLayout(0, 1));
        this.add(init(a));
        this.add(init(b));
        sum.setEditable(false);
        sum.setFocusable(false);
        this.add(sum);
    }

    private JFormattedTextField init(JFormattedTextField jtf) {
        jtf.setValue(0);
        jtf.addFocusListener(new FocusAdapter() {

            @Override
            public void focusLost(FocusEvent e) {
                EventQueue.invokeLater(new Runnable() {

                    @Override
                    public void run() {
                        Number v1 = (Number) a.getValue();
                        Number v2 = (Number) b.getValue();
                        sum.setValue(v1.longValue() + v2.longValue());
                    }
                });
            }
        });
        return jtf;
    }

    private void display() {
        JFrame f = new JFrame("Adder");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(this);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new Adder().display();
            }
        });
    }
}

Answer 2

I think you should use a PropertyChangeListener, see How to Write a Property Change Listener.

There is an example using JFormattedTextField:

//...where initialization occurs:
double amount;
JFormattedTextField amountField;
...
amountField.addPropertyChangeListener("value",
                                      new FormattedTextFieldListener());
...
class FormattedTextFieldListener implements PropertyChangeListener {
    public void propertyChanged(PropertyChangeEvent e) {
        Object source = e.getSource();
        if (source == amountField) {
            amount = ((Number)amountField.getValue()).doubleValue();
            ...
        }
        ...//re-compute payment and update field...
    }
}

Answer 3

is there some defalut Number value sets in your JFormattedTextField tf1,tf2;

for me works without NPE, for example

import java.awt.*;
import java.awt.event.*;
import java.math.RoundingMode;
import java.text.NumberFormat;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.event.*;

public class FormatterLimit {

    private JFrame frame = new JFrame();
    private JPanel pnl = new JPanel();
    private JLabel focusLabel = new JLabel(" focusLost Handle ");
    private JFormattedTextField formTextField;
    private JLabel docLabel = new JLabel(" document Handle ");
    private JFormattedTextField formTextField1;
    private NumberFormat formTextFieldFormat;
    private double amount = 10000.00;

    public FormatterLimit() {
        formTextFieldFormat = NumberFormat.getNumberInstance();
        formTextFieldFormat.setMinimumFractionDigits(2);
        formTextFieldFormat.setMaximumFractionDigits(2);
        formTextFieldFormat.setRoundingMode(RoundingMode.HALF_UP);

        focusLabel.setFont(new Font("Serif", Font.BOLD, 14));
        focusLabel.setForeground(Color.blue);
        focusLabel.setPreferredSize(new Dimension(120, 27));
        formTextField = new JFormattedTextField(formTextFieldFormat);
        formTextField.setValue(amount);
        formTextField.setFont(new Font("Serif", Font.BOLD, 22));
        formTextField.setForeground(Color.black);
        formTextField.setBackground(Color.yellow);
        formTextField.setPreferredSize(new Dimension(120, 27));
        formTextField.setHorizontalAlignment(SwingConstants.RIGHT);
        formTextField.addFocusListener(new FocusListener() {

            @Override
            public void focusGained(FocusEvent e) {
                formTextField.requestFocus();
                formTextField.setText(formTextField.getText());
                formTextField.selectAll();
            }

            @Override
            public void focusLost(FocusEvent e) {
                Runnable doRun = new Runnable() {

                    @Override
                    public void run() {
                        double t1a1 = (((Number) formTextField.getValue()).doubleValue());
                        if (t1a1 < 1000) {
                            formTextField.setValue(amount);
                        }
                    }
                };
                SwingUtilities.invokeLater(doRun);

            }
        });

        docLabel.setFont(new Font("Serif", Font.BOLD, 14));
        docLabel.setForeground(Color.blue);
        docLabel.setPreferredSize(new Dimension(120, 27));

        formTextField1 = new JFormattedTextField(formTextFieldFormat);
        formTextField1.setValue(amount);
        formTextField1.setFont(new Font("Serif", Font.BOLD, 22));
        formTextField1.setForeground(Color.black);
        formTextField1.setBackground(Color.yellow);
        formTextField1.setPreferredSize(new Dimension(120, 27));
        formTextField1.setHorizontalAlignment(SwingConstants.RIGHT);
        formTextField1.addFocusListener(new FocusListener() {

            @Override
            public void focusGained(FocusEvent e) {
                formTextField1.requestFocus();
                formTextField1.setText(formTextField1.getText());
                formTextField1.selectAll();
            }

            @Override
            public void focusLost(FocusEvent e) {
            }
        });
        formTextField1.getDocument().addDocumentListener(docListener);

        pnl = new JPanel();
        pnl.setBorder(new EmptyBorder(2, 2, 2, 2));
        pnl.setLayout(new GridLayout(2, 2));
        pnl.add(focusLabel);
        pnl.add(formTextField);
        pnl.add(docLabel);
        pnl.add(formTextField1);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(pnl, BorderLayout.CENTER);
        frame.setLocation(200, 200);
        frame.pack();
        frame.setVisible(true);
        formTextFieldFocus();
    }
    //
    private DocumentListener docListener = new DocumentListener() {

        @Override
        public void changedUpdate(DocumentEvent documentEvent) {
            printIt(documentEvent);
        }

        @Override
        public void insertUpdate(DocumentEvent documentEvent) {
            printIt(documentEvent);
        }

        @Override
        public void removeUpdate(DocumentEvent documentEvent) {
            printIt(documentEvent);
        }

        private void printIt(DocumentEvent documentEvent) {
            DocumentEvent.EventType type = documentEvent.getType();
            double t1a1 = (((Number) formTextField1.getValue()).doubleValue());
            if (t1a1 < 1000) {
                Runnable doRun = new Runnable() {

                    @Override
                    public void run() {
                        formTextField1.setValue(amount);
                    }
                };
                SwingUtilities.invokeLater(doRun);
            }
        }
    };

    public void formTextFieldFocus1() {
        Runnable doRun = new Runnable() {

            @Override
            public void run() {
                formTextField1.grabFocus();
                formTextField1.requestFocus();
                formTextField1.setText(formTextField1.getText());
                formTextField1.selectAll();
            }
        };
        SwingUtilities.invokeLater(doRun);
    }

    public void formTextFieldFocus() {
        Runnable doRun = new Runnable() {

            @Override
            public void run() {
                formTextField.grabFocus();
                formTextField.requestFocus();
                formTextField.setText(formTextField.getText());
                formTextField.selectAll();
                formTextFieldFocus1();
            }
        };
        SwingUtilities.invokeLater(doRun);
    }

    public static void main(String args[]) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                FormatterLimit fl = new FormatterLimit();
            }
        });
    }
}