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JScrollPane not show content after scroll in swing

Hi I need to display a large content(its graphical data) of data in single, so I tried following code.
canvas.setPreferredSize(new Dimension(3000, 300));
canvas.setBackground(Color.blue);
JScrollPane jsp = new JScrollPane(canvas);
setPreferredSize(new Dimension(600, 500));
setLayout(new GridLayout(1, 0, 5, 0));
jsp.getHorizontalScrollBar().addAdjustmentListener(new AdjustmentListener() {
#Override
public void adjustmentValueChanged(AdjustmentEvent e) {
System.out.println(e.getValue());
repaint();
}
});
add(jsp);
this is my MyCanvas class
class MyCanvas extends Canvas {
#Override
public void paint(Graphics g) {
super.paint(g);
System.out.println("paint");
g.setColor(Color.YELLOW);
for (int i = 0; i < 100; i++) {
g.drawString(""+i, i*30, 100);
// g.drawLine(10, 10, 20, 20);
}
}
}
but problem is that when I am scrolling window I cannot see full content as I expected it should print 100 numbers but not printed actually, can any one correct me?
see the result here

I recommend that you avoid mixing AWT and Swing components together (or if you absolutely must do this, then you have to make sure you understand the pitfalls and fully jump through all the necessary hoops.
Myself, I'd extend JPanel, I'd be sure that its preferredSize was where I want it, since this will determine how big it will be within the JScrollPane.
For example:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.*;
#SuppressWarnings("serial")
public class MyScrollExample extends JPanel {
private static final int MAX = 100;
private MyPanel myPanel = new MyPanel(MAX);
public MyScrollExample() {
JScrollPane scrollPane = new JScrollPane(myPanel);
scrollPane.getViewport().setPreferredSize(new Dimension(600, 200));
add(scrollPane);
}
private static void createAndShowGui() {
MyScrollExample mainPanel = new MyScrollExample();
JFrame frame = new JFrame("MyScrollExample");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
#SuppressWarnings("serial")
class MyPanel extends JPanel {
private static final Color BG = Color.BLUE;
private static final Color FG = Color.YELLOW;
private static final int WIDTH_GAP = 30;
private static final int HEIGHT_GAP = 100;
private int max;
public MyPanel(int max) {
setBackground(BG);
this.max = max;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(FG);
for (int i = 0; i < max; i++) {
g.drawString("" + i, i * WIDTH_GAP, HEIGHT_GAP);
}
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
int w = (WIDTH_GAP + 1) * max;
int h = HEIGHT_GAP * 3;
return new Dimension(w, h);
}
}

Add JPanel dynamically Swing

Hi I would like to have the following user interface:
And when the user clicks on start, I would like to add dynamically a JPanel underneath these elements. Something like this:
I am able to generate the grid in an empty JFrame, but when I try to add it when there are more elements inside the JFrame it appears, but very small.
This is the code that I have tried. The class UITable creates the buttons and input text
public UITable(){
jfrm = new JFrame("Plants experiment");
jfrm.setLayout(new FlowLayout());
jfrm.setSize(1000, 1000);
jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//JLabel titles for input texts
JLabel jlab_plants = new JLabel(" Enter nº plants: ");
JLabel jlab_time = new JLabel(" Enter evolution time: ");
jlab_prueba = new JLabel("");
//Input texts
jtf_plants = new JTextField(10);
jtf_plants.setActionCommand("numPlants");
jtf_time = new JTextField(10);
jtf_time.setActionCommand("time");
//Buttons
jbtnStart = new JButton("Start");
//Add components
jfrm.add(jlab_plants);
jfrm.add(jtf_plants);
jfrm.add(jlab_time);
jfrm.add(jtf_time);
jfrm.add(jbtnStart);
jfrm.add(jlab_prueba);
//Set visibility
jfrm.setVisible(true);
}
Adding dynamically the grid:
#Override
public void actionPerformed(ActionEvent ae) {
// ...
this.view.jfrm.add(new Grid());
this.view.jfrm.revalidate();
this.view.jfrm.repaint();
}
This is the Grid class:
public class Grid extends JPanel{
//Change Point to Plant in order to have a different color for each object
private List<Plant> fillCells;
public Grid() {
//fillCells = new ArrayList<>(25);
fillCells = PlantsControler.myPlants;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
System.out.println("Width: "+getWidth()+" Height: "+ getHeight());
---- //Returns Width: 10 Height: 10 ------
g.clearRect(0, 0, getWidth(), getHeight());
for (Plant fillCell : fillCells) {
int cellX = 10 + (fillCell.getX() * 10);
int cellY = 10 + (fillCell.getY() * 10);
g.setColor(fillCell.getColor());
g.fillRect(cellX, cellY, 10, 10);
}
g.setColor(Color.BLACK);
g.drawRect(10, 10, 800, 500);
for (int i = 10; i <= 800; i += 10) {
g.drawLine(i, 10, i, 510);
}
for (int i = 10; i <= 500; i += 10) {
g.drawLine(10, i, 810, i);
}
}
public void fillCell(int x, int y, Color color) {
fillCells.add(new Plant(x, y, color));
repaint();
}
public void fillCell(Plant plant){
fillCells.add(plant);
repaint();
}
public void fillCell(){
repaint();
}
public void clearGrid(){
fillCells.clear();
}
Thanks in advance!!!

You can try something like below.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class DemoFrame extends JFrame {
JTextField field = new JTextField();
public DemoFrame() {
setLayout(new BorderLayout());
JPanel controlsPane = new JPanel(new FlowLayout());
controlsPane.add(new JLabel("I m a Label"));
field.setPreferredSize(new Dimension(100,20));
controlsPane.add(field);
JButton button = new JButton("I am add drawPanel");
controlsPane.add(button);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent paramActionEvent) {
DemoFrame.this.add(new DrawPanel(), BorderLayout.CENTER);
DemoFrame.this.revalidate();
}
});
add(controlsPane,BorderLayout.NORTH);
}
public static void main(String[] args) {
DemoFrame frame = new DemoFrame();
frame.setVisible(true);
frame.pack();
}
class DrawPanel extends JPanel {
#Override
protected void paintComponent(Graphics g) {
// TODO Auto-generated method stub
super.paintComponent(g);
g.setColor(Color.BLUE);
g.drawString(field.getText(), this.getWidth()/2, this.getHeight()/2);
}
}
}

actionPerformed skip a step

I want everytime i click on the button "bouton" to execute the function
boutonPane.Panel2(h, ....) which is supposed to display h circles. So i want 2 then 3 then 4, then 5... circles.
The problem is that it is not displaying the step with number 4. I see the function is called in the console but on the screen it does really 2, (press button) 3, (press button) 5, (press button)9. I dont see 4. I dont see 6,7,8.. Could you tell me what is the problem please? Here is the code:
public class Window extends JFrame implements ActionListener {
int lg = 1000; int lrg = 700;
int h = 2;
Panel b = new Panel();
private JButton btn = new JButton("Start");
JButton bouton = new JButton();
private JPanel container = new JPanel();
public Window(){
this.setTitle("Animation");
this.setSize(300, 300);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
container.setBackground(Color.white);
container.setLayout(new BorderLayout());
JPanel top = new JPanel();
btn.addActionListener(this);
top.add(btn);
container.add(top);
this.setContentPane(container);
this.setVisible(true);
}
public void Window2()
{
System.out.println("windows2");
this.setTitle("ADHD");
this.setSize(lg, lrg);
this.setLocationRelativeTo(null);
bouton.addActionListener(this);
if(h<11)
{
Panel boutonPane = new Panel();
boutonPane.Panel2(h, Color.BLUE ,lg, lrg, this.getGraphics());
System.out.println("draw"+h);
boutonPane.add(bouton);
this.add(boutonPane);
this.setContentPane(boutonPane);
this.revalidate();
this.repaint();
}
this.setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
if((JButton)e.getSource()==btn)
{
System.out.println("pressed0");
Window2();
}
if((JButton)e.getSource()==bouton)
{
h++;
System.out.println("pressed"+h);
Window2();
}
}
}
Here is a the Panel class:
public class Panel extends JPanel
{
int m;
int i=1;
int a=0, b=0, tremp=0;
Color cc;
int lgi, lrgi;
int [] ta;
int [] tb;
Graphics gi;
int u=0;
Panel()
{
}
public void Panel2(int n, Color c, int lg, int lrg, Graphics g){
m=n;
cc=c;
gi=g;
lgi=lg;
lrgi=lrg;
ta = new int [n]; ta[0]=0;
tb = new int [n]; tb[0]=0;
}
public void paintComponent( final Graphics gr){
gr.setColor(Color.red);
for(int it=0; it<m;it++)
{
ta[it]=100*it;
tb[it]=100*it;
gr.fillOval(ta[it],tb[it], 150, 150);
}
}
}

"But would you have an idea of another, correct, way to do what I want please?"
You should only have one panel for the circles. There's absolutely no need to keep creating new panel.
Use a List for Ellipse2D objects. Just loop through them in the paintComponent method.
When you want to add a new circle, just add a new Ellipse2D object to the List and call repaint()
Here's an example.
NOTE Accept Gijs Overvliet's answer, as his was the one that answered your problem. I just wanted to share some insight.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class EllipseList extends JPanel {
private static final int D_W = 700;
private static final int D_H = 500;
private static final int CIRCLE_SIZE = 50;
private List<Ellipse2D> circles;
private double x = 0;
private double y = 0;
private CirclePanel circlePanel = new CirclePanel();
public EllipseList() {
circles = new ArrayList<>();
JButton jbtAdd = createButton();
JFrame frame = new JFrame();
frame.add(jbtAdd, BorderLayout.NORTH);
frame.add(circlePanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private JButton createButton() {
JButton button = new JButton("Add");
button.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
circles.add(new Ellipse2D.Double(x, y, CIRCLE_SIZE, CIRCLE_SIZE));
x += CIRCLE_SIZE * 0.75;
y += CIRCLE_SIZE * 0.75;
circlePanel.repaint();
}
});
return button;
}
public class CirclePanel extends JPanel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setPaint(Color.RED);
for (Ellipse2D circle : circles) {
g2.fill(circle);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(D_W, D_H);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new EllipseList();
}
});
}
}

Try this:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Window extends JFrame implements ActionListener
{
int lg = 1000;
int lrg = 700;
int h = 2;
Panel b = new Panel();
private JButton btn = new JButton("Start");
JButton bouton = new JButton();
private JPanel container = new JPanel();
Panel boutonPane = new Panel();
public Window()
{
this.setTitle("Animation");
this.setSize(300, 300);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
container.setBackground(Color.white);
container.setLayout(new BorderLayout());
JPanel top = new JPanel();
btn.addActionListener(this);
top.add(btn);
container.add(top);
this.setContentPane(container);
this.setVisible(true);
}
public void Window2()
{
System.out.println("windows2");
this.setTitle("ADHD");
this.setSize(lg, lrg);
this.setLocationRelativeTo(null);
bouton.addActionListener(this);
if (h < 11)
{
boutonPane.Panel2(h, Color.BLUE, lg, lrg, this.getGraphics());
System.out.println("draw" + h);
boutonPane.add(bouton);
this.add(boutonPane);
this.setContentPane(boutonPane);
updateWindow2();
}
this.setVisible(true);
}
public void updateWindow2()
{
boutonPane.Panel2(h, Color.BLUE, lg, lrg, this.getGraphics());
this.revalidate();
this.repaint();
}
public void actionPerformed(ActionEvent e)
{
if ((JButton) e.getSource() == btn)
{
System.out.println("pressed0");
Window2();
}
if ((JButton) e.getSource() == bouton)
{
h++;
System.out.println("pressed" + h);
updateWindow2();
}
}
public static void main(String[] args)
{
Test t = new Test();
}
}
What you did wrong was adding a new BoutonPane every time you clicked the button. The next time you clicked the button, you didn't click ONE button, but TWO buttons, adding two more boutonPanes, and two more buttons. This multiplies very quickly.
What I did was the following:
make boutonPane a class member variable
call window2() only once
create a method updateWindow2() for updating the circles. Call that method from window2() and actionPerformed().

Set JPanel background transparent, setOpaque() doesn't let me paint

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Tetris extends JFrame {
public Tetris() {
add(new GamePanel());
setDefaultCloseOperation(EXIT_ON_CLOSE);
setResizable(false);
setSize(800, 600);
setVisible(true);
setLocationRelativeTo(null);
setTitle("Tetris");
}
public class GamePanel extends JPanel {
public GamePanel(){
TetrisBoard tetraBoard= new TetrisBoard();
GridBagLayout layout= new GridBagLayout();
this.setLayout(layout);
GridBagConstraints c = new GridBagConstraints();
c.gridx = 2;
c.gridy = 1;
c.ipadx = 190;
c.ipady = 390;
c.insets.left= 360;
layout.setConstraints(tetraBoard, c);
this.add(tetraBoard);
setBackground(Color.WHITE);
}
#Override
public void paint(Graphics g){
super.paint(g);
g.setFont(new Font("Birth Std", Font.PLAIN, 12));
g.setColor(Color.LIGHT_GRAY);
g.drawString("200", 36, 63);
g.drawString("200", 36, 88);
g.drawString("200", 36, 114);
}
}//GamePanel class
public class TetrisBoard extends JPanel implements Runnable{
private Thread animator= new Thread(this);
private final int DELAY= 50;
public TetrisBoard(){
setFocusable(true);
//setBackground(Color.WHITE);
setDoubleBuffered(true);
//this.setBackground(Color.BLACK);
setOpaque(false);
}
#Override
public void addNotify() {
super.addNotify();
animator = new Thread(this);
animator.start();
}//addNotify
#Override
public void paint (Graphics g){
super.paint(g);
g.drawRect (20, 30, 130, 50);
}//paint
#Override
public void run() {
long beforeTime, timeDiff, sleep;
beforeTime = System.currentTimeMillis();
while (true) {
repaint();
timeDiff = System.currentTimeMillis() - beforeTime;
sleep = DELAY - timeDiff;
if (sleep < 0)
sleep = 2;
try {
Thread.sleep(sleep);
} catch (InterruptedException e) {
System.out.println("interrupted");
}
beforeTime = System.currentTimeMillis();
}
}
}//TetrisBoard class
public static void main(String[] args) {
Tetris t = new Tetris();
}
}
With this code the result is that it doesn't paint anything at all. I just want the background to be transparent not the images painted over the background, but it looks like the paint method doesn't paint if I setOpaque(false).
Edit: as requested I posted a simple code, TetraBoard is added to the GamePanel (using that GridBagLayout), and GamePanel is added to the frame, those 3 classes are separate files. I want TetraBoard to have a transparent background, so that I can see the background of GamePanel, but what I paint on tetraboard must be visible. If I setOpaque(false), TetraBoard is transparent, but it set on transparent everything I paint on it.

Edit: Assuming I understand what you're trying to do, replace the following line in the TetrisBoard constructor:
setOpaque(false);
with:
setBackground(new Color(0,0,0,0));

For example:
JPanel p = new JPanel() {
#Override
public void paintComponent(Graphics g) { // as suggested Andrew
g.setColor(Color.RED);
g.drawArc(0, 0, 100, 100, 0, 360); // arc will be painted on transparent bg
}
};
p.setBackground(new Color(0, 0, 0, 0)); // as suggested Perry
...
So, you have to do two actions:
1) override paintComponent(Graphics g) of JPanel
2) and set bg color to transparent: new Color(0, 0, 0, 0)

Swing: vertically stacked components without MigLayout

I finally got the behavior I want for vertically stacking components that have a preferred height that changes with time. But I needed to use MigLayout.
Is there a way to do this w/o MigLayout? (It's for a library and I don't want to force the dependency unless I have to)
Here's the behavior I'm looking for (which my test program achieves):
In vertical order, there's a resize button, "empty space" (well, a JLabel marked as such), a red rectangle, and a green square. The resize button has fixed height. The red square has a random size that can change at arbitrary times. The green square sets its preferred height to match its width, and I want to expand its width to fill the container. The empty space expands horizontally and vertically to fill the remaining space in the container.
What would work instead of MigLayout?
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.util.Random;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import net.miginfocom.swing.MigLayout;
public class AutoResizeDemo extends JPanel
{
static private class ResizingPanel extends JPanel
{
final private Color color;
private Dimension dpref = new Dimension(100,100);
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int w = getWidth();
int h = getHeight();
g.setColor(this.color);
g.fillRect(0, 0, w, h);
g.setColor(Color.BLACK);
g.drawRect(0, 0, w-1, h-1);
String s = this.dpref.width+"x"+this.dpref.height;
FontMetrics fm = g.getFontMetrics();
g.drawString(s, 0, fm.getHeight());
}
public ResizingPanel(Color color, boolean isSquare)
{
this.color = color;
if (isSquare)
{
addComponentListener(new ComponentAdapter() {
#Override public void componentResized(ComponentEvent e) {
doResize(getWidth(), getWidth());
}
});
}
}
#Override public Dimension getPreferredSize() {
return this.dpref;
}
public void doResize(int w, int h)
{
this.dpref = new Dimension(w, h);
revalidate();
}
}
public AutoResizeDemo()
{
super(new MigLayout("","[grow]",""));
setPreferredSize(new Dimension(200, 800));
final ResizingPanel resizingPanelRandom = new ResizingPanel(Color.RED, false);
ResizingPanel resizingPanelSquare = new ResizingPanel(Color.GREEN, true);
JPanel buttonPanel = new JPanel(new FlowLayout());
final Random rand = new Random();
addButton(buttonPanel, "resize",new Runnable() {
#Override public void run() {
resizingPanelRandom.doResize(
rand.nextInt(100)+100,
rand.nextInt(100)+100
);
}
});
add(buttonPanel, "wrap");
JLabel spaceLabel = new JLabel("empty space");
spaceLabel.setBorder(BorderFactory.createLineBorder(Color.BLACK));
add(spaceLabel, "push, grow, wrap");
add(resizingPanelRandom, "wrap");
add(resizingPanelSquare,"pushx, growx, wrap");
}
private void addButton(JPanel panel, String title, final Runnable r) {
JButton button = new JButton(title);
button.addActionListener(new ActionListener() {
#Override public void actionPerformed(ActionEvent e) {
r.run();
}
});
panel.add(button);
}
public static void main(String[] args) {
JFrame frame = new JFrame(AutoResizeDemo.class.getSimpleName());
frame.setContentPane(new AutoResizeDemo());
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

Use a BoxLayout.
You would use Box.createVerticalGlue() for the empty space.
BoxLayout respects the maximum size of a component, so you would probably need to override the getMaximumSize() method to return the preferred size for the red and green boxes.
For the green box you would also need to Override getPreferredSize() to keep the height in sync with the width.

You can solve this using SpringLayout by wiring all your compenents together and to the edges of their container.
Button Panel
left and top of the button panel to left and top of the container panel
Green Panel
left, right and bottom to the left, right and bottom of the container panel
Red Panel
left to left of container panel and bottom to top of the green panel
Space Label
top to south of the button panel, left and right to left and right of the container panel, bottom to top of the red panel
Edit: I love SpringLayout, there's nothing it can't do.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.util.Random;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SpringLayout;
public class AutoResizeDemo2 extends JPanel {
static private class ResizingPanel extends JPanel {
final private Color color;
private Dimension dpref = new Dimension(100, 100);
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int w = getWidth();
int h = getHeight();
g.setColor(this.color);
g.fillRect(0, 0, w, h);
g.setColor(Color.BLACK);
g.drawRect(0, 0, w - 1, h - 1);
String s = this.dpref.width + "x" + this.dpref.height;
FontMetrics fm = g.getFontMetrics();
g.drawString(s, 0, fm.getHeight());
}
public ResizingPanel(Color color, boolean isSquare) {
this.color = color;
if (isSquare) {
addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(ComponentEvent e) {
doResize(getWidth(), getWidth());
}
});
}
}
#Override
public Dimension getPreferredSize() {
return this.dpref;
}
public void doResize(int w, int h) {
this.dpref = new Dimension(w, h);
revalidate();
}
}
public AutoResizeDemo2() {
SpringLayout layout = new SpringLayout();
setLayout(layout);
setPreferredSize(new Dimension(200, 800));
final ResizingPanel resizingPanelRandom = new ResizingPanel(Color.RED, false);
ResizingPanel resizingPanelSquare = new ResizingPanel(Color.GREEN, true);
JPanel buttonPanel = new JPanel(new FlowLayout());
final Random rand = new Random();
addButton(buttonPanel, "resize", new Runnable() {
#Override
public void run() {
resizingPanelRandom.doResize(rand.nextInt(100) + 100, rand.nextInt(100) + 100);
}
});
add(buttonPanel);
layout.putConstraint(SpringLayout.NORTH, buttonPanel, 5, SpringLayout.NORTH, this);
layout.putConstraint(SpringLayout.WEST, buttonPanel, 5, SpringLayout.WEST, this);
JLabel spaceLabel = new JLabel("empty space");
spaceLabel.setBorder(BorderFactory.createLineBorder(Color.BLACK));
add(resizingPanelSquare);
layout.putConstraint(SpringLayout.SOUTH, resizingPanelSquare, -5, SpringLayout.SOUTH, this);
layout.putConstraint(SpringLayout.WEST, resizingPanelSquare, 5, SpringLayout.WEST, this);
layout.putConstraint(SpringLayout.EAST, resizingPanelSquare, -5, SpringLayout.EAST, this);
add(resizingPanelRandom);
layout.putConstraint(SpringLayout.SOUTH, resizingPanelRandom, -5, SpringLayout.NORTH, resizingPanelSquare);
layout.putConstraint(SpringLayout.WEST, resizingPanelRandom, 5, SpringLayout.WEST, this);
add(spaceLabel);
layout.putConstraint(SpringLayout.NORTH, spaceLabel, 5, SpringLayout.SOUTH, buttonPanel);
layout.putConstraint(SpringLayout.WEST, spaceLabel, 5, SpringLayout.WEST, this);
layout.putConstraint(SpringLayout.EAST, spaceLabel, -5, SpringLayout.EAST, this);
layout.putConstraint(SpringLayout.SOUTH, spaceLabel, -5, SpringLayout.NORTH, resizingPanelRandom);
}
private void addButton(JPanel panel, String title, final Runnable r) {
JButton button = new JButton(title);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
r.run();
}
});
panel.add(button);
}
public static void main(String[] args) {
JFrame frame = new JFrame(AutoResizeDemo2.class.getSimpleName());
frame.setContentPane(new AutoResizeDemo2());
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

SpringLayout is difficult to determine how it is laid out without a lot of analyzing. Try TableLayout. The only tricky part of your layout is the green square's height being equal to its width. This is a bit unusual for a layout manager to support, so I would just special case it. A runnable example:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import com.esotericsoftware.tablelayout.swing.Table;
public class Test extends JFrame {
JButton button;
JPanel red, green;
public Test () {
button = new JButton("Resize");
button.addActionListener(new ActionListener() {
public void actionPerformed (ActionEvent e) {
red.setPreferredSize(new Dimension(138, new Random().nextInt(190) + 10));
red.revalidate();
}
});
red = new JPanel();
red.setPreferredSize(new Dimension(138, 145));
red.setBackground(Color.red);
green = new JPanel();
green.setPreferredSize(new Dimension(100, 100));
green.setBackground(Color.green);
// The DSL can be much easier to describe complex hierarchies.
boolean dsl = false;
if (dsl)
dsl();
else
javaApi();
setSize(160, 400);
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);
}
private void javaApi () {
final Table table = new Table() {
public void layout () {
green.setPreferredSize(new Dimension(getWidth(), getWidth()));
super.layout();
}
};
table.pad(10).defaults().left().space(5);
table.addCell(button);
table.row();
table.addCell().expandY();
table.row();
table.addCell(red);
table.row();
table.addCell(green).expandX().fillX();
getContentPane().add(table);
}
private void dsl () {
final Table table = new Table() {
public void layout () {
green.setPreferredSize(new Dimension(getWidth(), getWidth()));
super.layout();
}
};
table.register("button", button);
table.register("red", red);
table.register("green", green);
table.parse("pad:10 * left space:5 " //
+ "[button] ---" //
+ "[] expandy ---" //
+ "[red] ---" //
+ "[green] expandx fillx" //
);
getContentPane().add(table);
}
public static void main (String[] args) throws Exception {
new Test();
}
}
Being table based, it is easy to get an idea of the layout at a glance. I included code for using the Java API and also the DSL. The Java API is nice since you get completion. Here is just the layout code:
table.pad(10).defaults().left().space(5);
table.addCell(button);
table.row();
table.addCell().expandY();
table.row();
table.addCell(red);
table.row();
table.addCell(green).expandX().fillX();
The DSL is nice for describing hierarchies, probably not necessary for this example. Unfortunately Java doesn't have a verbatim string, though a large UI could be described in a file. The DSL for this example without the Java string quotes would be:
pad:10 * left space:5
[button]
---
[] expandy
---
[red]
---
[green] expandx fillx