Customized JTextFiled for number autoformatting

Question

Hi everyone,
I've been programming a customized JTextField to accept only numbers with auto-format while you're typing on it, it's almost working except some issues with decimal point. I would like you to help me to test it or give me advices to improve mi code. Thanks.
package sgpmde.forms.components;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.text.NumberFormat;
import javax.swing.JTextField;
public class JNumberField extends JTextField {
    private double value = 0;
    private NumberFormat nf = NumberFormat.getCurrencyInstance();
    public JNumberField() {
        this.addKeyListener(new KeyAdapter() {
            @Override
            public void keyTyped(KeyEvent evt) {
                keyTypedEvent(evt);
        this.addFocusListener(new FocusAdapter() {
            @Override
            public void focusGained(FocusEvent evt) {
                focusGainedEvent(evt);
            @Override
            public void focusLost(FocusEvent evt) {
                focusLostEvent(evt);
    private double strToDouble(String str) {
        if (str.isEmpty()) {
            return 0.00;
        } else return Double.valueOf(str.replaceAll(",", ""));
    private String doubleToStr(double val, boolean evalDot) {
        StringBuilder num = new StringBuilder(nf.format(val));
        num.deleteCharAt(0);
        if (!getText().contains(".") && evalDot) {
            num.delete(num.length() - 3, num.length());
        return num.toString();
    private int count(String str, char chr) {
        int c = 0;
        for (int i = 0; i < str.length(); i++) {
            if (str.charAt(i) == chr) c++;
        return c;
    private int newChars(String str1, String str2, char chr) {
        int n = count(str2, chr) - count(str1, chr);
        if (n < 0) {
            return 0;
        } else return n;
    private void insert(char chr) {
        StringBuilder num = new StringBuilder();
        if (value > 0) {
            num.append(getText());
        } else setCaretPosition(0);
        num.insert(getCaretPosition(), chr);
        value = strToDouble(num.toString());
    private void delete() {
        StringBuilder num = new StringBuilder();
        if (getText().isEmpty()) {
            value = 0;
        } else {
            num.append(getText());   
            value = strToDouble(num.toString());
    private void keyTypedEvent(KeyEvent evt) {
        char chr = evt.getKeyChar();
        evt.setKeyChar((char) 0);
        if (((chr >= '0' && chr <= '9') ||
                (chr == '.' && !getText().contains(".")))
                && getCaretPosition() != getText().length()) {
            int pos = getCaretPosition();
            insert(chr);
            String str1 = getText();
            String str2 = doubleToStr(value, false);
            setText(str2);
            setCaretPosition(pos + newChars(str1, str2, ',') + 1);
        if (chr == KeyEvent.VK_BACK_SPACE) {
            int pos = getCaretPosition();
            delete();
            String str1 = getText();
            String str2 = doubleToStr(value, true);
            setText(str2);
            int pos2 = pos - newChars(str2, str1, ',');
            if (pos2 >= 0) {
                setCaretPosition(pos2);
            } else setCaretPosition(0);
    public void focusGainedEvent(FocusEvent evt) {
        if (value == 0) {
            setCaretPosition(0);
    public void focusLostEvent(FocusEvent evt) {
        setText(doubleToStr(value, false));
    public double getValue() {
        return value;
    public void setValue(double val) {
       value = val;
}

Answer 1

I've corrected it and i think it's working pefectly, please give a try :-)
package sgpmde.forms.components;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.text.NumberFormat;
import javax.swing.JTextField;
* @author jevb
public class JNumberField extends JTextField {
    private double value = 0;
    private NumberFormat nf = NumberFormat.getCurrencyInstance();
    private boolean dot = true;
     * General Constructor - add event listeners
    public JNumberField() {
        this.addKeyListener(new KeyAdapter() {
            @Override
            public void keyTyped(KeyEvent evt) {
                keyTypedEvent(evt);
        this.addFocusListener(new FocusAdapter() {
            @Override
            public void focusGained(FocusEvent evt) {
                focusGainedEvent(evt);
            @Override
            public void focusLost(FocusEvent evt) {
                focusLostEvent(evt);
        setText(doubleToStr(value, false));
    private double strToDouble(String str) {
        if (str.isEmpty()) {
            return 0.00;
        } else return Double.valueOf(str.replaceAll(",", ""));
    private String doubleToStr(double val, boolean evalDot) {
        StringBuilder num = new StringBuilder(nf.format(val));
        num.deleteCharAt(0);
        if (!getText().contains(".") && evalDot && value != 0) {
            num.delete(num.length() - 3, num.length());
        return num.toString();
    private int count(String str, char chr) {
        int c = 0;
        for (int i = 0; i < str.length(); i++) {
            if (str.charAt(i) == chr) c++;
        return c;
    private int newChars(String str1, String str2, char chr) {
        int n = count(str2, chr) - count(str1, chr);
        if (n < 0) {
            return 0;
        } else return n;
    private void insert(char chr) {
        StringBuilder num = new StringBuilder();
        if (value > 0) {
            num.append(getText());
        } else {
            setCaretPosition(0);
            dot = true;
        num.insert(getCaretPosition(), chr);
        value = strToDouble(num.toString());
    private void delete() {
        StringBuilder num = new StringBuilder();
        if (getText().isEmpty()) {
            value = 0;
        } else {
            num.append(getText());   
            value = strToDouble(num.toString());
    private void keyTypedEvent(KeyEvent evt) {
        char chr = evt.getKeyChar();
        evt.setKeyChar((char) 0);
        if (((chr >= '0' && chr <= '9') || (chr == '.')) && (getCaretPosition() != getText().length() || !dot)) {
            dot = true;
            int pos = getCaretPosition();
            if (chr == '.') {
                if (getText().contains(".") && getText().charAt(pos) == '.') {
                    setCaretPosition(pos + 1);
                    chr = 0;
                } else if (getText().contains(".")) chr = 0;
            if (chr != 0) {
            insert(chr);
            String str1 = getText();
            String str2 = doubleToStr(value, false);
            setText(str2);
            setCaretPosition(pos + newChars(str1, str2, ',') + 1);
        if (chr == KeyEvent.VK_BACK_SPACE) {
            int pos = getCaretPosition();
            delete();
            String str1 = getText();
            String str2 = doubleToStr(value, true);
            setText(str2);
            int pos2 = pos - newChars(str2, str1, ',');
            if (!getText().contains(".")) {
                if (dot) pos2++;
                dot = false;
            if (pos2 >= 0) {
                setCaretPosition(pos2);
            } else setCaretPosition(0);
    public void focusGainedEvent(FocusEvent evt) {
        if (value == 0) {
            setCaretPosition(0);
    public void focusLostEvent(FocusEvent evt) {
        setText(doubleToStr(value, false));
    public double getValue() {
        return value;
    public void setValue(double value) {
       this.value = value;
       setText(doubleToStr(value, false));
}