May be silly mistake .... please help me

Question

Hi Friends,
I have jframe which contains a toggle button, when toggle button is pressed, I am trying to add a JText Field dynamically when user drags mouse.
I am getting nullpointer exception.
Can some one please tell me how can I solve this problem ?
Below is two classes of my code
1. Main (contains JFrame)
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
public class DragTest4{
    public static void main(String[] args) {
        drawRect dr = new drawRect();
class drawRect extends JFrame
             implements MouseListener, MouseMotionListener, ActionListener {
    Container c;
    Draggable3 d0;
    int startX;
    int startY;
    boolean drawRect = false;
    int compId = 0;
    JPanel jp;
    drawRect() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        setSize(new Dimension(400, 400));
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        int x = screenSize.width/2 - getSize().width/2;
        int y = screenSize.height/2 - getSize().height/2;
        setLocation(x, y);
        Container c = getContentPane();
        JToggleButton jtb = new JToggleButton("Draw");
        jtb.setLayout(null);
        jtb.setBounds(10,10,80,20);
        jtb.addActionListener(this);
        c.add(jtb);
        d0 = new Draggable3();
        c.add(d0, null);
        c.setBackground(Color.white);
        c.setLayout(null);
        c.addMouseListener(this);
        c.addMouseMotionListener(this);
        setVisible(true);
    public void actionPerformed(ActionEvent e) {
        drawRect = !(drawRect);
        if(drawRect == true)
            setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
        else
            setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
    public void mouseDragged(MouseEvent e) {
        if(drawRect == true) {
            setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
            //.setBounds(startX, startY, e.getX() - startX, e.getY() - startY);
            System.out.println("Object Resized CompId:" + compId);
        } else {
    public void mouseMoved(MouseEvent e) {
    public void mouseEntered(MouseEvent e) {
    public void mouseExited(MouseEvent e) {
    public void mousePressed(MouseEvent e) {
        if(drawRect == true) {
            startX = e.getX();
            startY = e.getY();
            System.out.println("Object Created CompId:" + compId);
    public void mouseReleased(MouseEvent e) {
        if(drawRect == true) {
            System.out.println("Object Added CompId:" + compId);
            c.add(new Draggable3());  //Here nullpointer exception occurs !!
    public void mouseClicked(MouseEvent e) {
}2. modified JTextField (which will be added dynamically)
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.LineBorder;
class Draggable3
    extends JTextField
    implements MouseListener, MouseMotionListener {
  private final JTextField p;
  private LineBorder normalBorder = new LineBorder(Color.darkGray);
  private LineBorder selectedBorder = new LineBorder(Color.blue, 2);
  private boolean selected = false;
  final private int NORMAL_MOVE = 0;
  final private int LEFT_MOVE = 1;
  final private int RIGHT_MOVE = 2;
  final private int TOP_MOVE = 3;
  final private int BOTTOM_MOVE = 4;
  final private int LB_MOVE = 5;
  final private int LT_MOVE = 6;
  final private int RB_MOVE = 7;
  final private int RT_MOVE = 8;
  final private int DRAG_MOVE = 9;
  private int startDragPointX;
  private int startDragPointY;
  private int fieldResize = NORMAL_MOVE;
  public Draggable3() {
    setDoubleBuffered(true);
    p = this;
    setLayout(new BorderLayout());
    setBackground(Color.white);
    setBounds(40, 40, 50, 20);
    setBorder(normalBorder);
    addMouseListener(this);
    addMouseMotionListener(this);
  public void mouseClicked(MouseEvent e) {
    if (this.selected == true) {
      this.selected = false;
      this.setBorder(this.normalBorder);
    else {
      this.selected = true;
      this.setBorder(this.selectedBorder);
    mouseCursor(e);
  public void mouseDragged(MouseEvent e) {
    if (this.selected == true) {
      switch (fieldResize) {
        case LEFT_MOVE:
          fieldLeftStrech(e);
          break;
        case RIGHT_MOVE:
          fieldRightStrech(e);
          break;
        case BOTTOM_MOVE:
          fieldBottomStrech(e);
          break;
        case TOP_MOVE:
          fieldTopStrech(e);
          break;
        case LB_MOVE:
          fieldLeftStrech(e);
          fieldBottomStrech(e);
          break;
        case LT_MOVE:
          fieldLeftStrech(e);
          fieldTopStrech(e);
          break;
        case RB_MOVE:
          fieldRightStrech(e);
          fieldBottomStrech(e);
          break;
        case RT_MOVE:
          fieldRightStrech(e);
          fieldTopStrech(e);
          break;
        case DRAG_MOVE:
          p.setBounds(p.getX() - (startDragPointX - e.getX()),
                      p.getY() - (startDragPointY - e.getY()), p.getWidth(),
                      p.getHeight());
          break;
        default:
          break;
  private void fieldLeftStrech(MouseEvent e) {
    p.setBounds(p.getX() + e.getX(), p.getY(),
                p.getWidth() - e.getX(), p.getHeight());
  private void fieldRightStrech(MouseEvent e) {
    p.setBounds(p.getX(), p.getY(),
                e.getX(), p.getHeight());
  private void fieldBottomStrech(MouseEvent e) {
    p.setBounds(p.getX(), p.getY(),
                p.getWidth(), e.getY());
  private void fieldTopStrech(MouseEvent e) {
    p.setBounds(p.getX(), p.getY() + e.getY(),
                p.getWidth(), p.getHeight() - e.getY());
  public void mouseEntered(MouseEvent e) {
  public void mouseExited(MouseEvent e) {
  public void mousePressed(MouseEvent e) {
    startDragPointX = e.getX();
    startDragPointY = e.getY();
  public void mouseReleased(MouseEvent e) {
  public void mouseMoved(MouseEvent e) {
    mouseCursor(e);
  private void mouseCursor(MouseEvent e) {
    int x = e.getX();
    int y = e.getY();
    int fieldStartX = this.getX();
    int fieldStartY = this.getY();
    int fieldEndX = this.getWidth();
    int fieldEndY = this.getHeight();
    if (this.selected == true) {
      if ( (x <= 5) && (y >= fieldEndY - 5)) {
        fieldResize = LB_MOVE;
        this.setCursor(Cursor.getPredefinedCursor(Cursor.NE_RESIZE_CURSOR));
      else if ( (x <= 5) && (y <= 5)) {
        fieldResize = LT_MOVE;
        this.setCursor(Cursor.getPredefinedCursor(Cursor.SE_RESIZE_CURSOR));
      else if ( (x >= fieldEndX - 5) && (y >= fieldEndY - 5)) {
        fieldResize = RB_MOVE;
        this.setCursor(Cursor.getPredefinedCursor(Cursor.NW_RESIZE_CURSOR));
      else if ( (x >= fieldEndX - 5) && (y <= 5)) {
        fieldResize = RT_MOVE;
        this.setCursor(Cursor.getPredefinedCursor(Cursor.SW_RESIZE_CURSOR));
      else if (x <= 5) {
        fieldResize = LEFT_MOVE;
        this.setCursor(Cursor.getPredefinedCursor(Cursor.E_RESIZE_CURSOR));
      else if (x >= fieldEndX - 5) {
        fieldResize = RIGHT_MOVE;
        this.setCursor(Cursor.getPredefinedCursor(Cursor.W_RESIZE_CURSOR));
      else if (y <= 5) {
        fieldResize = TOP_MOVE;
        this.setCursor(Cursor.getPredefinedCursor(Cursor.N_RESIZE_CURSOR));
      else if (y >= fieldEndY - 5) {
        fieldResize = BOTTOM_MOVE;
        this.setCursor(Cursor.getPredefinedCursor(Cursor.S_RESIZE_CURSOR));
      else {
        fieldResize = DRAG_MOVE;
        this.setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));
    else {
      fieldResize = NORMAL_MOVE;
      this.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));

Answer 1

Hello,
I think you are trying to do the same thing that I am trying to do...an editor? Could send me your source code?
I am trying to drag-drop java components like jtextfield, jbuttons,...
but I could not make it works. And create elements dynamically too.
My email:[email protected]
Thanks,
Luiz Fernando