Java Swing How to - Set selection mode and handle selection event








Question

We would like to know how to set selection mode and handle selection event.

Answer

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/*
 * SimpleTableSelectionDemo.java requires no other files.
 */

import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.ListSelectionModel;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
/**
 * SimpleTableSelectionDemo is just like SimpleTableDemo, except that it detects
 * selections, printing information about the current selection to standard
 * output.
 */
public class Main extends JPanel {
  private boolean DEBUG = false;
  private boolean ALLOW_COLUMN_SELECTION = false;
  private boolean ALLOW_ROW_SELECTION = true;

  public Main() {
    super(new GridLayout(1, 0));

    final String[] columnNames = { "First Name", "Last Name", "Sport",
        "# of Years", "Vegetarian" };

    final Object[][] data = {
        { "Mary", "Campione", "Snowboarding", new Integer(5),
            new Boolean(false) },
        { "Alison", "Huml", "Rowing", new Integer(3), new Boolean(true) },
        { "Kathy", "Walrath", "Knitting", new Integer(2), new Boolean(false) },
        { "Sharon", "Zakhour", "Speed reading", new Integer(20),
            new Boolean(true) },
        { "Philip", "Milne", "Pool", new Integer(10), new Boolean(false) } };

    final JTable table = new JTable(data, columnNames);
    table.setPreferredScrollableViewportSize(new Dimension(500, 70));
    table.setFillsViewportHeight(true);

    table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    if (ALLOW_ROW_SELECTION) { // true by default
      ListSelectionModel rowSM = table.getSelectionModel();
      rowSM.addListSelectionListener(new ListSelectionListener() {
        public void valueChanged(ListSelectionEvent e) {
          // Ignore extra messages.
          if (e.getValueIsAdjusting())
            return;

          ListSelectionModel lsm = (ListSelectionModel) e.getSource();
          if (lsm.isSelectionEmpty()) {
            System.out.println("No rows are selected.");
          } else {
            int selectedRow = lsm.getMinSelectionIndex();
            System.out.println("Row " + selectedRow + " is now selected.");
          }
        }
      });
    } else {
      table.setRowSelectionAllowed(false);
    }

    if (ALLOW_COLUMN_SELECTION) { // false by default
      if (ALLOW_ROW_SELECTION) {
        // We allow both row and column selection, which
        // implies that we *really* want to allow individual
        // cell selection.
        table.setCellSelectionEnabled(true);
      }
      table.setColumnSelectionAllowed(true);
      ListSelectionModel colSM = table.getColumnModel().getSelectionModel();
      colSM.addListSelectionListener(new ListSelectionListener() {
        public void valueChanged(ListSelectionEvent e) {
          // Ignore extra messages.
          if (e.getValueIsAdjusting())
            return;

          ListSelectionModel lsm = (ListSelectionModel) e.getSource();
          if (lsm.isSelectionEmpty()) {
            System.out.println("No columns are selected.");
          } else {
            int selectedCol = lsm.getMinSelectionIndex();
            System.out.println("Column " + selectedCol + " is now selected.");
          }
        }
      });
    }

    if (DEBUG) {
      table.addMouseListener(new MouseAdapter() {
        public void mouseClicked(MouseEvent e) {
          printDebugData(table);
        }
      });
    }

    // Create the scroll pane and add the table to it.
    JScrollPane scrollPane = new JScrollPane(table);

    // Add the scroll pane to this panel.
    add(scrollPane);
  }

  private void printDebugData(JTable table) {
    int numRows = table.getRowCount();
    int numCols = table.getColumnCount();
    javax.swing.table.TableModel model = table.getModel();

    System.out.println("Value of data: ");
    for (int i = 0; i < numRows; i++) {
      System.out.print("    row " + i + ":");
      for (int j = 0; j < numCols; j++) {
        System.out.print("  " + model.getValueAt(i, j));
      }
      System.out.println();
    }
    System.out.println("--------------------------");
  }

  /**
   * 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("SimpleTableSelectionDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

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

    // 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();
      }
    });
  }
}