Knowing Completion of Repaint

Question

Hi Folks,
I am having a JPanel and I will be adding button to it on the fly
and removing too.
My problem is when I add a button, I want to know the button's width.
This I cannot do because I tried the code in a ContainerListener.containerAdded() and ContainerListener.containerRemoved()
Just after I had added the button and called revalidate() and repaint() on the JPanel.
The width of the just added button I get is 0. I guess it is because my peice of code runs BEFORE the repaint is finished its job.
Am I right? If yes, then how can I know when a component repaint() has finishe doing its job??

Answer 1

<b>Code: </b>
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.border.*;
import java.util.Vector;
public class ButtonScroller extends JPanel {
     FlowLayout flow = new FlowLayout(FlowLayout.LEFT);
     JPanel rightPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
     JPanel buttonPanel = new JPanel(flow);
     JPanel o1;
     Vector bv = new Vector();
     int buttonGap = 0;
     JButton lb, rb;
     public ButtonScroller() {
          BorderLayout layout = new BorderLayout();
          layout.setVgap(0);
          layout.setHgap(0);
          BorderLayout layout1 = new BorderLayout();
          layout1.setVgap(0);
          layout1.setHgap(0);
          BorderLayout layout2 = new BorderLayout();
          layout2.setVgap(0);
          layout2.setHgap(0);
          BorderLayout layout3 = new BorderLayout();
          layout3.setVgap(0);
          layout3.setHgap(0);
          setLayout(layout);
          flow.setHgap(5);
          buttonGap = flow.getHgap();
          o1 = new JPanel(layout1);
          JPanel i1 = new JPanel(layout2);
          JPanel i2 = new JPanel(layout3);
          o1.add(i1, BorderLayout.CENTER);
          o1.add(i2, BorderLayout.EAST);
          i1.add(buttonPanel, BorderLayout.NORTH);
          i2.add(rightPanel, BorderLayout.NORTH);
          //add(buttonPanel, BorderLayout.CENTER);
          //add(rightPanel, BorderLayout.EAST);
          add(o1, BorderLayout.CENTER);
          rightPanel.setBorder(new SoftBevelBorder(BevelBorder.RAISED));
          buttonPanel.setBorder(new SoftBevelBorder(BevelBorder.RAISED));
          setup();
          buttonPanel.addContainerListener(new ContainerListener() {
               public void componentAdded(ContainerEvent ce) {
                    areBMTA();     
               public void componentRemoved(ContainerEvent ce) {
                    areBMTA();
     void setup() {
          lb = new JButton("L");
          rightPanel.add(lb);
          rb = new JButton("R");
          rightPanel.add(rb);
          lb.addActionListener(new ActionListener() {
               public void actionPerformed(ActionEvent ae) {
                    System.out.println("Left Button Clicked");
          rb.addActionListener(new ActionListener() {
               public void actionPerformed(ActionEvent ae) {
                    System.out.println("Right Button Clicked");
          rb.addMouseListener(new MouseAdapter() {
               public void mouseClicked(MouseEvent me) {
                    if (SwingUtilities.isRightMouseButton(me)) {
                         System.out.println("Right Click on right button");
                         JButton button = new JButton("(- " + (bv.size() + 10) + "-)");
                         //button.setBorder(new EmptyBorder(0,0,0,0));
                         buttonPanel.add(button);
                         button.addComponentListener(new ComponentAdapter() {
                              public void componentShown(ComponentEvent ce) {
                                   System.out.println("The button is now visible");
                         bv.add(button);
                         buttonPanel.revalidate();
                         buttonPanel.repaint(0);
          lb.addMouseListener(new MouseAdapter() {
               public void mouseClicked(MouseEvent me) {
                    if (SwingUtilities.isRightMouseButton(me)) {
                         System.out.println("Right Click on left button");
                         int size = bv.size();
                         if (size == 0) return;
                         JButton button = (JButton) bv.elementAt(0);
                         buttonPanel.remove(button);
                         bv.remove(button);
                         buttonPanel.revalidate();
                         buttonPanel.repaint(0);
     private boolean areBMTA() {
          int pWidth = buttonPanel.getSize().width;
          int bWidth = 0;
          int totButtons = buttonPanel.getComponentCount();
          int totalButtonWidth = 0;
          if (totButtons ==0 ) return false;
          for(int i=0; i<totButtons; i++) {
               JButton button = (JButton)buttonPanel.getComponent(i);
               System.out.println("The Width of the button at [" + i +"] is " + button.getWidth());
               if (button.isVisible()) {
                    //bWidth = button.getSize().width;
                    bWidth = button.getWidth();
                    System.out.println("We found a button that was visible and its width is " + bWidth);
                    break;
          System.out.println("Button Gap :" + buttonGap);
          System.out.println("Button Width :" + bWidth);
          int extraWidth = (totButtons + 1) * buttonGap;
          totalButtonWidth += extraWidth;
          totalButtonWidth += (totButtons * bWidth);
          System.out.println("TBW:" + totalButtonWidth + "And Panel Width: " + pWidth);
          System.out.println("Right Panel Width is " + rightPanel.getSize().width);
          System.out.println("o1 Panel Width is " + o1.getSize().width);
          if (totalButtonWidth > pWidth)
               return true;
          else
               return false;
     private boolean scroll(char ch) {
          return false;