Alignment of objects in GridBagLayout cells

Question

I am trying to learn how to use JAVA's GUI library Swing. What I am trying to do is place 2 images of disks in a row and 3 images of printers in the row below them. Each disk image should be in the middle of two printer images. I am (unfortunately) using GridBagLayout to achieve this. I am trying to construct a grid of 12 columns and have each printer take 4 and each disk 6. I then tried to set the objects' anchors to GridBagConstraints.PAGE_END so the images are in the bottom middle part of the cell. No matter what I do I can't get the disks to align properly, I spent a tremendous amount of time trying to fix this.

Here is my function that creates the objects:

private void placeIcon(Container pane, GridBagConstraints c, int x, int y, String imagePath,
                               String imageLabel, int gridWidth) {
    BufferedImage printerIcon;
    try {
        printerIcon = ImageIO.read(new File(imagePath));
    } catch (IOException e) {
        e.printStackTrace();
        return;
    }

    JLabel textLabel = new JLabel(imageLabel + Integer.toString(x + 1),
                                SwingConstants.CENTER);
    JPanel iconPanel = new JPanel();
    iconPanel.setLayout(new GridBagLayout());
    textLabel.setPreferredSize(new Dimension(100,10));

    GridBagConstraints iconConstr = new GridBagConstraints();
    iconConstr.gridx = 0;
    iconConstr.gridy = 0;
    iconConstr.insets = new Insets(10, 3, 1, 3);
    iconConstr.anchor = GridBagConstraints.PAGE_END;
    iconConstr.weightx = 1;
    iconConstr.weighty = 1;
    iconPanel.add(textLabel, iconConstr);

    JLabel iconLabel = new JLabel(new ImageIcon(printerIcon));
    iconLabel.setPreferredSize(new Dimension(250,250));
    iconConstr.gridx = 0;
    iconConstr.gridy = 1;
    iconConstr.insets = new Insets(1, 3, 1, 3);
    iconConstr.anchor = GridBagConstraints.PAGE_END;
    iconConstr.weightx = 1;
    iconConstr.weighty = 1;
    iconPanel.add(iconLabel, iconConstr);

    c.gridx = x;
    c.gridy = y;
    c.weightx = 1;
    c.weighty = 1;
    c.anchor = GridBagConstraints.PAGE_END;
    c.gridwidth = gridWidth;
    c.insets = new Insets(25, 10, 1, 10);
    pane.add(iconPanel, c);
}

Calling it like this to create the printer and disk images:

    private void placeAllPrinterIcons(Container pane, GridBagConstraints c, int yPos) {
    String imgPath = "bin/images/printer_icon.png";
    String label = "Printer ";
    placeIcon(pane, c, 0, yPos, imgPath, label, 4);
    placeIcon(pane, c, 4, yPos, imgPath, label, 4);
    placeIcon(pane, c, 8, yPos, imgPath, label, 4);
}

private void placeAllDiskIcons(Container pane, GridBagConstraints c, int yPos) {
    String imgPath = "bin/images/disk_icon.png";
    String label = "Disk ";
    placeIcon(pane, c, 0, yPos, imgPath, label, 6);
    placeIcon(pane, c, 6, yPos, imgPath, label, 6);
}

        Container pane = getContentPane();
    pane.setLayout(new GridBagLayout());

    GridBagConstraints c = new GridBagConstraints();
    c.fill = GridBagConstraints.HORIZONTAL;

    placeAllDiskIcons(pane, c, 0);
    placeAllPrinterIcons(pane, c, 1);

The current GUI looks like this, labels to be fixed:

Answer 1

I am trying to construct a grid of 12 columns and have each printer take 4 and each disk 6.

Unfortunately you can't do that. You can't just make up columns. The layout manager doesn't know what a column means unless there is a component in every column.

So your solution is nest panels with different layout managers.

One approach might be to use something like:

JPanel diskPanel = new JPanel( new GridLayout(1, 0) );
diskPanel.add(disk1);
diskPanel.add(disk2);

JPanel printerPanel( new JPanel( new GridLayout(1, 0) );
printerPanel.add(printer1);
printerPanel.add(printer2);
printerPanel.add(printer3);

JPanel mainPanel = new JPanel( new GridLayout(0, 1) );
mainPanel.add(diskPanel);
mainPanel.add(printerPanel);

This will create grids of different sizes. Then you add the main panel to your frame.

Note: if you really want to use the concept of having 12 columns, then you need to have a row of 12 invisible components to occupy each column. For an example of this approach check out: Why does this GridBagLayout not appear as planned?

Answer 2

Try a gridbag layout like this (glue is Box.createGlue())