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javaswingjlistdefaultlistmodel

Readjust text inside of JList element

I have a JList, the list is filled with the elements of a file, I want the text within the elements to be adjusted to the size of the list, increasing the height of the cell and giving line breaks.

enter image description here

How could I do it?

Solution

  • I want the text within the elements to be adjusted to the size of the list

    A list cell renderer (typically a JLabel) supports HTML formatting, so we can use styles to set a body width. The height of the cell will adjust accordingly. The middle list uses a renderer that is constrained to 100 px width.

    enter image description here

    That's three lists based on properties of the first thousand Unicode characters. Each list is as wide as it needs to be in order to display the widest string in the list model (however it is formatted for rendering).

    Here is the MCVE:

    import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.util.Vector;

public class UnicodeNameList {

    private JComponent ui = null;

    UnicodeNameList() {
        initUI();
    }

    public final void initUI() {
        if (ui!=null) return;

        ui = new JPanel(new BorderLayout(4,4));
        ui.setBorder(new EmptyBorder(4,4,4,4));
        Vector<String> unicodeNames = new Vector<>();
        Vector<String> unicodeDir = new Vector<>();
        Vector<String> unicodeChar = new Vector<>();
        for (int ii=0; ii<1000; ii++) {
            unicodeChar.add(new String(Character.toChars(ii)));
            unicodeNames.add(Character.getName(ii));
            unicodeDir.add("" + Character.getDirectionality(ii));
        }
        ui.add(new JScrollPane(new JList(unicodeChar)), BorderLayout.LINE_START);
        JList list = new JList(unicodeNames);
        LongListCellRenderer llcr = new LongListCellRenderer();
        list.setCellRenderer(llcr);
        ui.add(new JScrollPane(list));
        ui.add(new JScrollPane(new JList(unicodeDir)), BorderLayout.LINE_END);
    }

    public JComponent getUI() {
        return ui;
    }

    public static void main(String[] args) {
        Runnable r = () -> {
            try {
                UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
            } catch (Exception useDefault) {
            }
            UnicodeNameList o = new UnicodeNameList();

            JFrame f = new JFrame(o.getClass().getSimpleName());
            f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
            f.setLocationByPlatform(true);

            f.setContentPane(o.getUI());
            f.pack();
            f.setMinimumSize(f.getSize());

            f.setVisible(true);
        };
        SwingUtilities.invokeLater(r);
    }
}

class LongListCellRenderer extends DefaultListCellRenderer {

    @Override
    public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
        String pre = "<html><body style='width: 100px;'>";
        JLabel l = (JLabel)super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
        String s = value==null ? "Null" : value.toString();
        l.setText(pre + s);
        return l;
    }
}