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I've gotten to the stage where I can display my OpenCloud word cloud in Java using this code with Swing. It loads text line by line from a file, gobbles it up and spits out words that I want displayed. This is passed to my cloud that then adds them every time a batch of lines has been read, and updates. Currently I'm using the default layout manager, but it just appends the new words to the bottom of the window, eventually flowing over the bottom of the window. Which is not what I want.

What I'm after is something more like wordle:

enter image description here

Ideally I want it to:

  • Aim for the center of the JPanel
  • Add words outwards radially
  • Allow more than one word 'per line' (note how between way and want you have one and currently on new lines.)
  • Trickier: Prune words with a low score that won't fit when the edges are reached.

As per the solution I've linked to, I've adding these as JLabels with a font based on the weighting of each tag.

I've had a browse of all the different swing layout managers, and none of them seem amenable to being programmed. My only option if I want to customize my layout, as I am stuck with Swing (yes, pretty much entirely stuck), seems to be to use absolute layout positioning. Which seems like a it would be a tricky beast to tame. Unfortuanately, for those wanting to suggest some awesome non-standard LayoutManager I can't add any packages to my development machine/access the internet. What I think I need to do is randomly add the words somewhere in the page, then do the same for the other words and adjust them so they don't collide with each other of the edge of the window.

So it seems like I need to know:

  • Is there a 'known' way of doing this sort of random/delayed adjusting of layout using one of the standard Layout managers?
  • Is there a way of doing this sort of layout without a layout manager? Is this easier?
  • Is it going to be easier to write my own Layout manager? Surely that's a daunting task, no?

Apologies if this seems like I'm just asking for a solution on a platter, I'm a bit new to Java (how long can I get away with saying that!) and I don't know where to start with this sort of thing, and any help/hints would be appreciated.

Best Answer:

Here is an example using WrapLayout which seems to work ok:

import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import org.mcavallo.opencloud.Cloud;
import org.mcavallo.opencloud.Tag;
public class TestOpenCloud {
    private static final String[] WORDS = { "art", "australia", "baby", "beach", "birthday", "blue", "bw", "california", "canada", "canon",
            "cat", "chicago", "china", "christmas", "city", "dog", "england", "europe", "family", "festival", "flower", "flowers", "food",
            "france", "friends", "fun", "germany", "holiday", "india", "italy", "japan", "london", "me", "mexico", "music", "nature",
            "new", "newyork", "night", "nikon", "nyc", "paris", "park", "party", "people", "portrait", "sanfrancisco", "sky", "snow",
            "spain", "summer", "sunset", "taiwan", "tokyo", "travel", "trip", "uk", "usa", "vacation", "water", "wedding" };
    protected void initUI() {
        JFrame frame = new JFrame(TestOpenCloud.class.getSimpleName());
        final JPanel panel = new JPanel(new WrapLayout());
        Cloud cloud = new Cloud();
        final Random random = new Random();
        for (String s : WORDS) {
            for (int i = random.nextInt(50); i > 0; i--) {
        for (Tag tag : cloud.tags()) {
            final JLabel label = new JLabel(tag.getName());
            label.setFont(label.getFont().deriveFont((float) tag.getWeight() * 10));
        JScrollPane scrollPane = new JScrollPane(panel);
        frame.setSize(500, 550);
        Timer t = new Timer(1000, new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                final JLabel label = new JLabel(WORDS[random.nextInt(WORDS.length)]);
                int fontSize = random.nextInt(20) + 8;
                label.setFont(label.getFont().deriveFont((float) fontSize));
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new TestOpenCloud().initUI();
    public class WrapLayout extends FlowLayout {
        private Dimension preferredLayoutSize;
         * Constructs a new <code>WrapLayout</code> with a left alignment and a default 5-unit horizontal and vertical gap.
        public WrapLayout() {
         * Constructs a new <code>FlowLayout</code> with the specified alignment and a default 5-unit horizontal and vertical gap. The value
         * of the alignment argument must be one of <code>WrapLayout</code>, <code>WrapLayout</code>, or <code>WrapLayout</code>.
         * @param align
         *            the alignment value
        public WrapLayout(int align) {
         * Creates a new flow layout manager with the indicated alignment and the indicated horizontal and vertical gaps.
         * <p>
         * The value of the alignment argument must be one of <code>WrapLayout</code>, <code>WrapLayout</code>, or <code>WrapLayout</code>.
         * @param align
         *            the alignment value
         * @param hgap
         *            the horizontal gap between components
         * @param vgap
         *            the vertical gap between components
        public WrapLayout(int align, int hgap, int vgap) {
            super(align, hgap, vgap);
         * Returns the preferred dimensions for this layout given the <i>visible</i> components in the specified target container.
         * @param target
         *            the component which needs to be laid out
         * @return the preferred dimensions to lay out the subcomponents of the specified container
        public Dimension preferredLayoutSize(Container target) {
            return layoutSize(target, true);
         * Returns the minimum dimensions needed to layout the <i>visible</i> components contained in the specified target container.
         * @param target
         *            the component which needs to be laid out
         * @return the minimum dimensions to lay out the subcomponents of the specified container
        public Dimension minimumLayoutSize(Container target) {
            Dimension minimum = layoutSize(target, false);
            minimum.width -= getHgap() + 1;
            return minimum;
         * Returns the minimum or preferred dimension needed to layout the target container.
         * @param target
         *            target to get layout size for
         * @param preferred
         *            should preferred size be calculated
         * @return the dimension to layout the target container
        private Dimension layoutSize(Container target, boolean preferred) {
            synchronized (target.getTreeLock()) {
                // Each row must fit with the width allocated to the containter.
                // When the container width = 0, the preferred width of the container
                // has not yet been calculated so lets ask for the maximum.
                int targetWidth = target.getSize().width;
                if (targetWidth == 0) {
                    targetWidth = Integer.MAX_VALUE;
                int hgap = getHgap();
                int vgap = getVgap();
                Insets insets = target.getInsets();
                int horizontalInsetsAndGap = insets.left + insets.right + hgap * 2;
                int maxWidth = targetWidth - horizontalInsetsAndGap;
                // Fit components into the allowed width
                Dimension dim = new Dimension(0, 0);
                int rowWidth = 0;
                int rowHeight = 0;
                int nmembers = target.getComponentCount();
                for (int i = 0; i < nmembers; i++) {
                    Component m = target.getComponent(i);
                    if (m.isVisible()) {
                        Dimension d = preferred ? m.getPreferredSize() : m.getMinimumSize();
                        // Can't add the component to current row. Start a new row.
                        if (rowWidth + d.width > maxWidth) {
                            addRow(dim, rowWidth, rowHeight);
                            rowWidth = 0;
                            rowHeight = 0;
                        // Add a horizontal gap for all components after the first
                        if (rowWidth != 0) {
                            rowWidth += hgap;
                        rowWidth += d.width;
                        rowHeight = Math.max(rowHeight, d.height);
                addRow(dim, rowWidth, rowHeight);
                dim.width += horizontalInsetsAndGap;
                dim.height += + insets.bottom + vgap * 2;
                // When using a scroll pane or the DecoratedLookAndFeel we need to
                // make sure the preferred size is less than the size of the
                // target container so shrinking the container size works
                // correctly. Removing the horizontal gap is an easy way to do this.
                Container scrollPane = SwingUtilities.getAncestorOfClass(JScrollPane.class, target);
                if (scrollPane != null) {
                    dim.width -= hgap + 1;
                return dim;
         *  A new row has been completed. Use the dimensions of this row
         *  to update the preferred size for the container.
         *  @param dim update the width and height when appropriate
         *  @param rowWidth the width of the row to add
         *  @param rowHeight the height of the row to add
        private void addRow(Dimension dim, int rowWidth, int rowHeight) {
            dim.width = Math.max(dim.width, rowWidth);
            if (dim.height > 0) {
                dim.height += getVgap();
            dim.height += rowHeight;

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