JList: setSelectedIndex(int index) : JList « javax.swing « Java by API

1. Java by API
2. javax.swing
3. JList

JList: setSelectedIndex(int index)

  


/*
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 * modification, are permitted provided that the following conditions
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 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
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 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
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 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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/*
 * ListDataEventDemo.java requires the Java Look and Feel Graphics
 * Repository (jlfgr-1_0.jar).  You can download this file from
 * http://java.sun.com/developer/techDocs/hi/repository/
 * Put it in the class path using one of the following commands
 * (assuming jlfgr-1_0.jar is in a subdirectory named jars):
 *
 *   java -cp .;jars/jlfgr-1_0.jar ListDataEventDemo [Microsoft Windows]
 *   java -cp .:jars/jlfgr-1_0.jar ListDataEventDemo [UNIX]
 */

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.DefaultListModel;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.ListSelectionModel;
import javax.swing.event.ListDataEvent;
import javax.swing.event.ListDataListener;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

public class Main extends JPanel implements ListSelectionListener {
  private JList list;
  private DefaultListModel listModel;

  private static final String addString = "Add";
  private static final String deleteString = "Delete";
  private static final String upString = "Move up";
  private static final String downString = "Move down";

  private JButton addButton;
  private JButton deleteButton;
  private JButton upButton;
  private JButton downButton;

  private JTextField nameField;
  private JTextArea log;
  static private String newline = "\n";

  public Main() {
    super(new BorderLayout());

    // Create and populate the list model.
    listModel = new DefaultListModel();
    listModel.addElement("Whistler, Canada");
    listModel.addElement("Jackson Hole, Wyoming");
    listModel.addElement("Squaw Valley, California");
    listModel.addElement("Telluride, Colorado");
    listModel.addElement("Taos, New Mexico");
    listModel.addElement("Snowbird, Utah");
    listModel.addElement("Chamonix, France");
    listModel.addElement("Banff, Canada");
    listModel.addElement("Arapahoe Basin, Colorado");
    listModel.addElement("Kirkwood, California");
    listModel.addElement("Sun Valley, Idaho");
    listModel.addListDataListener(new MyListDataListener());

    // Create the list and put it in a scroll pane.
    list = new JList(listModel);
    list.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
    list.setSelectedIndex(0);
    list.addListSelectionListener(this);
    JScrollPane listScrollPane = new JScrollPane(list);

    // Create the list-modifying buttons.
    addButton = new JButton(addString);
    addButton.setActionCommand(addString);
    addButton.addActionListener(new AddButtonListener());

    deleteButton = new JButton(deleteString);
    deleteButton.setActionCommand(deleteString);
    deleteButton.addActionListener(new DeleteButtonListener());

    ImageIcon icon = createImageIcon("Up16");
    if (icon != null) {
      upButton = new JButton(icon);
      upButton.setMargin(new Insets(0, 0, 0, 0));
    } else {
      upButton = new JButton("Move up");
    }
    upButton.setToolTipText("Move the currently selected list item higher.");
    upButton.setActionCommand(upString);
    upButton.addActionListener(new UpDownListener());

    icon = createImageIcon("Down16");
    if (icon != null) {
      downButton = new JButton(icon);
      downButton.setMargin(new Insets(0, 0, 0, 0));
    } else {
      downButton = new JButton("Move down");
    }
    downButton.setToolTipText("Move the currently selected list item lower.");
    downButton.setActionCommand(downString);
    downButton.addActionListener(new UpDownListener());

    JPanel upDownPanel = new JPanel(new GridLayout(2, 1));
    upDownPanel.add(upButton);
    upDownPanel.add(downButton);

    // Create the text field for entering new names.
    nameField = new JTextField(15);
    nameField.addActionListener(new AddButtonListener());
    String name = listModel.getElementAt(list.getSelectedIndex()).toString();
    nameField.setText(name);

    // Create a control panel, using the default FlowLayout.
    JPanel buttonPane = new JPanel();
    buttonPane.add(nameField);
    buttonPane.add(addButton);
    buttonPane.add(deleteButton);
    buttonPane.add(upDownPanel);

    // Create the log for reporting list data events.
    log = new JTextArea(10, 20);
    JScrollPane logScrollPane = new JScrollPane(log);

    // Create a split pane for the log and the list.
    JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
        listScrollPane, logScrollPane);
    splitPane.setResizeWeight(0.5);

    // Put everything together.
    add(buttonPane, BorderLayout.PAGE_START);
    add(splitPane, BorderLayout.CENTER);
  }

  class MyListDataListener implements ListDataListener {
    public void contentsChanged(ListDataEvent e) {
      log.append("contentsChanged: " + e.getIndex0() + ", " + e.getIndex1()
          + newline);
      log.setCaretPosition(log.getDocument().getLength());
    }

    public void intervalAdded(ListDataEvent e) {
      log.append("intervalAdded: " + e.getIndex0() + ", " + e.getIndex1()
          + newline);
      log.setCaretPosition(log.getDocument().getLength());
    }

    public void intervalRemoved(ListDataEvent e) {
      log.append("intervalRemoved: " + e.getIndex0() + ", " + e.getIndex1()
          + newline);
      log.setCaretPosition(log.getDocument().getLength());
    }
  }

  class DeleteButtonListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      /*
       * This method can be called only if there's a valid selection, so go
       * ahead and remove whatever's selected.
       */

      ListSelectionModel lsm = list.getSelectionModel();
      int firstSelected = lsm.getMinSelectionIndex();
      int lastSelected = lsm.getMaxSelectionIndex();
      listModel.removeRange(firstSelected, lastSelected);

      int size = listModel.size();

      if (size == 0) {
        // List is empty: disable delete, up, and down buttons.
        deleteButton.setEnabled(false);
        upButton.setEnabled(false);
        downButton.setEnabled(false);

      } else {
        // Adjust the selection.
        if (firstSelected == listModel.getSize()) {
          // Removed item in last position.
          firstSelected--;
        }
        list.setSelectedIndex(firstSelected);
      }
    }
  }

  /** A listener shared by the text field and add button. */
  class AddButtonListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      if (nameField.getText().equals("")) {
        // User didn't type in a name...
        Toolkit.getDefaultToolkit().beep();
        return;
      }

      int index = list.getSelectedIndex();
      int size = listModel.getSize();

      // If no selection or if item in last position is selected,
      // add the new one to end of list, and select new one.
      if (index == -1 || (index + 1 == size)) {
        listModel.addElement(nameField.getText());
        list.setSelectedIndex(size);

        // Otherwise insert the new one after the current selection,
        // and select new one.
      } else {
        listModel.insertElementAt(nameField.getText(), index + 1);
        list.setSelectedIndex(index + 1);
      }
    }
  }

  // Listen for clicks on the up and down arrow buttons.
  class UpDownListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      // This method can be called only when
      // there's a valid selection,
      // so go ahead and move the list item.
      int moveMe = list.getSelectedIndex();

      if (e.getActionCommand().equals(upString)) {
        // UP ARROW BUTTON
        if (moveMe != 0) {
          // not already at top
          swap(moveMe, moveMe - 1);
          list.setSelectedIndex(moveMe - 1);
          list.ensureIndexIsVisible(moveMe - 1);
        }
      } else {
        // DOWN ARROW BUTTON
        if (moveMe != listModel.getSize() - 1) {
          // not already at bottom
          swap(moveMe, moveMe + 1);
          list.setSelectedIndex(moveMe + 1);
          list.ensureIndexIsVisible(moveMe + 1);
        }
      }
    }
  }

  // Swap two elements in the list.
  private void swap(int a, int b) {
    Object aObject = listModel.getElementAt(a);
    Object bObject = listModel.getElementAt(b);
    listModel.set(a, bObject);
    listModel.set(b, aObject);
  }

  // Listener method for list selection changes.
  public void valueChanged(ListSelectionEvent e) {
    if (e.getValueIsAdjusting() == false) {

      if (list.getSelectedIndex() == -1) {
        // No selection: disable delete, up, and down buttons.
        deleteButton.setEnabled(false);
        upButton.setEnabled(false);
        downButton.setEnabled(false);
        nameField.setText("");

      } else if (list.getSelectedIndices().length > 1) {
        // Multiple selection: disable up and down buttons.
        deleteButton.setEnabled(true);
        upButton.setEnabled(false);
        downButton.setEnabled(false);

      } else {
        // Single selection: permit all operations.
        deleteButton.setEnabled(true);
        upButton.setEnabled(true);
        downButton.setEnabled(true);
        nameField.setText(list.getSelectedValue().toString());
      }
    }
  }

  /** Returns an ImageIcon, or null if the path was invalid. */
  protected static ImageIcon createImageIcon(String imageName) {
    String imgLocation = "toolbarButtonGraphics/navigation/" + imageName
        + ".gif";
    java.net.URL imageURL = Main.class.getResource(imgLocation);

    if (imageURL == null) {
      System.err.println("Resource not found: " + imgLocation);
      return null;
    } else {
      return new ImageIcon(imageURL);
    }
  }

  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event-dispatching thread.
   */
  private static void createAndShowGUI() {
    // Create and set up the window.
    JFrame frame = new JFrame("ListDataEventDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    // Create and set up the content pane.
    JComponent newContentPane = new Main();
    newContentPane.setOpaque(true); // content panes must be opaque
    frame.setContentPane(newContentPane);

    // Don't let the content pane get too small.
    // (Works if the Java look and feel provides
    // the window decorations.)
    newContentPane.setMinimumSize(new Dimension(newContentPane
        .getPreferredSize().width, 100));

    // Display the window.
    frame.pack();
    frame.setVisible(true);
  }

  public static void main(String[] args) {
    // Schedule a job for the event-dispatching thread:
    // creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });
  }
}

   
    
  

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