JList
and don't want to scroll through it, it might be a better idea to "paginate" it i.e. display the list in "pages" of a few rows at a time and allow users to flip back and forth between them. To do this, I have written a Java Swing component called PaginatedList
, which looks like this:
You pass in a JList
and specify a page size (the page size is 10 in this example) and it returns a PaginatedList
which you can add onto another JComponent
as normal. The code is shown below:
import java.awt.BorderLayout; import java.awt.GridLayout; import java.awt.event.ActionEvent; import javax.swing.AbstractAction; import javax.swing.DefaultListModel; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JList; import javax.swing.JPanel; import javax.swing.ListModel; /** * A paginated JList. Only displays a specific number of rows * and allows you to page back and forth through the list. * with the help of a toolbar. */ public class PaginatedList extends JPanel { private final int pageSize; private final JList list; private final ListModel model; private final int lastPageNum; private int currPageNum; private JLabel countLabel ; private JButton first, prev, next, last; /** * @param list the source list * @param pageSize the number of rows visible */ public PaginatedList(JList list, int pageSize) { super(); this.pageSize = pageSize; this.list = list; this.model = list.getModel(); //work out how many pages there are this.lastPageNum = model.getSize() / pageSize + (model.getSize() % pageSize != 0 ? 1 : 0); this.currPageNum = lastPageNum > 0 ? 1 : 0; setLayout(new BorderLayout()); countLabel = new JLabel() ; add(countLabel, BorderLayout.NORTH); add(list, BorderLayout.CENTER); add(createControls(), BorderLayout.SOUTH); updatePage(); } private JPanel createControls() { first = new JButton(new AbstractAction("<<") { public void actionPerformed(ActionEvent e) { currPageNum = 1; updatePage(); } }); prev = new JButton(new AbstractAction("<") { public void actionPerformed(ActionEvent e) { if (--currPageNum <= 0) currPageNum = 1; updatePage(); } }); next = new JButton(new AbstractAction(">") { public void actionPerformed(ActionEvent e) { if (++currPageNum > lastPageNum) currPageNum = lastPageNum; updatePage(); } }); last = new JButton(new AbstractAction(">>") { public void actionPerformed(ActionEvent e) { currPageNum = lastPageNum; updatePage(); } }); JPanel bar = new JPanel(new GridLayout(1, 4)); bar.add(first); bar.add(prev); bar.add(next); bar.add(last); return bar; } private void updatePage() { //replace the list's model with a new model containing //only the entries in the current page. if(model.getSize() != 0){ final DefaultListModel page = new DefaultListModel(); final int start = (currPageNum - 1) * pageSize; int end = start + pageSize; if (end >= model.getSize()) { end = model.getSize(); } for (int i = start; i < end; i++) { page.addElement(model.getElementAt(i)); } list.setModel(page); } //update the label countLabel.setText("Page " + currPageNum + "/" + lastPageNum); // update buttons final boolean canGoBack = currPageNum > 1; final boolean canGoFwd = currPageNum != lastPageNum; first.setEnabled(canGoBack); prev.setEnabled(canGoBack); next.setEnabled(canGoFwd); last.setEnabled(canGoFwd); } public static void main(String args[]) throws Exception { // create 100 elements of dummy data. String[] data = new String[101]; for (int i = 0; i < data.length; i++) { data[i] = "Item "+ (i + 1); } // create a paginated list with page size 20 PaginatedList list = new PaginatedList(new JList(data), 10); // add it to a frame JFrame f = new JFrame("Paginated List Demo"); f.add(list); f.setSize(100, 100); f.pack(); f.setVisible(true); } }
I needed something like this to save time on my coding. Thanks!
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