How to Fit a component in a JPanel

Question

Hy, I am actually creating a Graphical Programming Language Appln and I am facing some problems.
My source code is found below. Here is my problem:
I have inserted some buttons have been inserted in the Main panel until both scroll bar appear,
what I want is that when I click on the button label "Fit", a new window opens,
where it shows the buttons which have been fitted in that window, without any scrollbar.How to do that?
Please send me the code for solving this problem. Its very very urgent.Here are my Code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.datatransfer.*;
import java.awt.dnd.*;
import javax.swing.tree.*;
import java.io.*;
public class MainDesktop extends JFrame implements ActionListener {
JSplitPane splitPane = new JSplitPane();
JPanel mainPane = new JPanel();
JScrollPane mainScrollPane = new JScrollPane();
Container contentPane = getContentPane();
public MainDesktop() {
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
//Adding the ToolBar to the main window
JToolBar toolBar = new JToolBar();
myToolBar(toolBar);
contentPane.add(toolBar, BorderLayout.NORTH);
//create a list of button and add them to a pane
JButton bgButton = new JButton("Begin");
JButton rdButton = new JButton("Read");
JButton wrButton = new JButton("Write");
JButton efButton = new JButton("If-Else");
JButton ifButton = new JButton("End-If");
JButton wlButton = new JButton("While-Loop");
JButton flButton = new JButton("For-Loop");
JButton elButton = new JButton("End-Loop");
JButton swButton = new JButton("Switch");
JButton arButton = new JButton("Arithmetic");
JButton enButton = new JButton("End");
bgButton.setActionCommand("Begin");
rdButton.setActionCommand("Read");
wrButton.setActionCommand("Write");
efButton.setActionCommand("If-Else");
ifButton.setActionCommand("End-If");
wlButton.setActionCommand("While-Loop");
flButton.setActionCommand("For-Loop");
elButton.setActionCommand("End-Loop");
swButton.setActionCommand("Switch");
arButton.setActionCommand("Arithmetic");
enButton.setActionCommand("End");
bgButton.addActionListener(this);
rdButton.addActionListener(this);
wrButton.addActionListener(this);
efButton.addActionListener(this);
ifButton.addActionListener(this);
wlButton.addActionListener(this);
flButton.addActionListener(this);
elButton.addActionListener(this);
swButton.addActionListener(this);
arButton.addActionListener(this);
enButton.addActionListener(this);
JPanel toolPane = new JPanel();
toolPane.setLayout(new GridLayout(15,0));
toolPane.add(bgButton);
toolPane.add(rdButton);
toolPane.add(wrButton);
toolPane.add(efButton);
toolPane.add(ifButton);
toolPane.add(wlButton);
toolPane.add(flButton);
toolPane.add(elButton);
toolPane.add(swButton);
toolPane.add(arButton);
toolPane.add(enButton);
//Create a pane for the drawing area and add scroll pane to it
mainPane.setLayout(new FlowLayout());
mainScrollPane = new JScrollPane(mainPane);
mainScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
mainScrollPane.setHorizontalScrollBarPolicy (JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
mainScrollPane.setLayout(new ScrollPaneLayout());
//Create a split pane with the two scroll panes in it
splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,toolPane, mainScrollPane);
splitPane.setOneTouchExpandable(true);
splitPane.setDividerLocation(100);
splitPane.setPreferredSize(new Dimension(1000, 650));
getContentPane().add(splitPane);
protected void myToolBar(JToolBar toolBar) {
//Fit button
JButton fitButton = new JButton("Fit");
fitButton.setToolTipText("Fit Flowchart to drawing area");
fitButton.setActionCommand("Fit");
fitButton.addActionListener(this);
toolBar.add(fitButton);
public void actionPerformed(ActionEvent e) {
String cmd = e.getActionCommand();
if (cmd.equals("Fit")) {
//fit flowchart to drawing area
if (cmd.equals("Delete")) {
//Delete a node from flowchart
//Action command for the list of button from the toolbox
if (cmd.equals("Begin")) {
dragbutton drag = new dragbutton();
mainPane.add(drag);
if (cmd.equals("Read")) {
dragbutton drag = new dragbutton();
mainPane.add(drag);
if (cmd.equals("Write")) {
dragbutton drag = new dragbutton();
mainPane.add(drag);
if (cmd.equals("If-Else")) {
dragbutton drag = new dragbutton();
mainPane.add(drag);
if (cmd.equals("End-If")) {
dragbutton drag = new dragbutton();
mainPane.add(drag);
if (cmd.equals("While-Loop")) {
dragbutton drag = new dragbutton();
mainPane.add(drag);
if (cmd.equals("For-Loop")) {
dragbutton drag = new dragbutton();
mainPane.add(drag);
if (cmd.equals("End-Loop")) {
dragbutton drag = new dragbutton();
mainPane.add(drag);
if (cmd.equals("Switch")) {
dragbutton drag = new dragbutton();
mainPane.add(drag);
if (cmd.equals("Arithmetic")) {
dragbutton drag = new dragbutton();
mainPane.add(drag);
//mainPane.repaint();
if (cmd.equals("End")) {
dragbutton drag = new dragbutton();
mainPane.add(drag);
//mainPane.repaint();
class dragbutton extends JButton implements DragGestureListener, DragSourceListener {
public dragbutton() {
super("Begin");
DragSource dragSource = DragSource.getDefaultDragSource();
dragSource.createDefaultDragGestureRecognizer(this,DnDConstants.ACTION_COPY_OR_MOVE,this);
public void dragGestureRecognized(DragGestureEvent e) {
e.startDrag(DragSource.DefaultCopyDrop,
new StringSelection(null),this);
public void dragDropEnd(DragSourceDropEvent e) {}
public void dragEnter(DragSourceDragEvent e) {}
public void dragExit(DragSourceEvent e) {}
public void dragOver(DragSourceDragEvent e) {}
public void dropActionChanged(DragSourceDragEvent e) {}
public static void main(String [] args) {
MainDesktop mainWindow = new MainDesktop();
mainWindow.setTitle("Graphical Programming Language");
mainWindow.setSize(700, 600);
mainWindow.setVisible(true);

Answer 1

Instead of using:
frame.setSize(int, int);
use:
frame.pack();