Freezing the first column of a JTable

Courtesy of Nobuo Tamemasa (http://www2.gol.com/users/tame/swing/examples/JTableExamples1.html)



RowHeaderRenderer.java:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
 
/**
 * @version 1.0 11/09/98
 */
 
class RowHeaderRenderer extends JLabel implements ListCellRenderer {
  
  RowHeaderRenderer(JTable table) {
    JTableHeader header = table.getTableHeader();
    setOpaque(true);
    setBorder(UIManager.getBorder("TableHeader.cellBorder"));
    setHorizontalAlignment(CENTER);
    setForeground(header.getForeground());
    setBackground(header.getBackground());
    setFont(header.getFont());
  }
  
  public Component getListCellRendererComponent( JList list, 
         Object value, int index, boolean isSelected, boolean cellHasFocus) {
    setText((value == null) ? "" : value.toString());
    return this;
  }
}
 
public class RowHeaderExample extends JFrame {
 
  public RowHeaderExample() {
    super( "Row Header Example" );
    setSize( 300, 150 );
         
    ListModel lm = new AbstractListModel() {
      String headers[] = {"a", "b", "c", "d", "e", "f", "g", "h", "i"};
      public int getSize() { return headers.length; }
      public Object getElementAt(int index) {
        return headers[index];
      }
    };
 
    DefaultTableModel dm = new DefaultTableModel(lm.getSize(),10);
    JTable table = new JTable( dm );
    table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
    
    JList rowHeader = new JList(lm);    
    rowHeader.setFixedCellWidth(50);
    
    rowHeader.setFixedCellHeight(table.getRowHeight()
                               + table.getRowMargin());
//                             + table.getIntercellSpacing().height);
    rowHeader.setCellRenderer(new RowHeaderRenderer(table));
 
    JScrollPane scroll = new JScrollPane( table );
    scroll.setRowHeaderView(rowHeader);
    getContentPane().add(scroll, BorderLayout.CENTER);
  }
 
  public static void main(String[] args) {
    RowHeaderExample frame = new RowHeaderExample();
    frame.addWindowListener( new WindowAdapter() {
      public void windowClosing( WindowEvent e ) {
        System.exit(0);
      }
    });
    frame.setVisible(true);
  }
}

Changing the setMnemonic behavior of JButton so that it responds to CTRL instead of ALT

Try this workaround!

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
   
public class Main extends JFrame {
   JList list; 
 
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      final JButton button = new JButton("Click-Me!");
 
      ActionListener al = new ActionListener() {
         public void actionPerformed(ActionEvent ae) {
            System.out.println("Button was clicked!");
         }
      };
      button.addActionListener(al);
  
      // don't use button.setMnemonic('C') if you want only the CTRL mask to work,
      // use button.getModel() instead. 
      button.getModel().setMnemonic('C');
      KeyStroke keyStroke = KeyStroke.getKeyStroke('C', Event.CTRL_MASK, false); 
      button.registerKeyboardAction(al, keyStroke, JComponent.WHEN_FOCUSED); 
      
      getContentPane().add(button);
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      setSize(400, 400);
   }
 
   public static void main(String[] args) {
      (new Main()).show();
   }
}

Scrolling a JList to the selected item

You can use the method ensureIndexIsVisible as shown in following example:

import javax.swing.event.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.awt.*;
  
public class Main extends JFrame {
 
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      Vector v = new Vector();
      for (int i=0; i<50; i++) {
         v.addElement("Item #" + i);
      }
      final JList list = new JList(v);
 
      final JTextField textfield = new JTextField(5);
      getContentPane().add(new JLabel("Scroll to:"));
      getContentPane().add(textfield);
      JButton button = new JButton("Scroll!");
      getContentPane().add(button);
      button.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent ae) {
            int n = Integer.parseInt(textfield.getText());
            list.ensureIndexIsVisible(n);
         }
      });
      getContentPane().add(new JScrollPane(list));    
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      setSize(200, 230);
   }
   
   public static void main(String[] args) {
      (new Main()).show();
   }
}

Creating a JTable with a multi-line header

Courtesy of Nobuo Tamemasa (http://www2.gol.com/users/tame/swing/examples/JTableExamples1.html)



MultiLineHeaderExample.java:

import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
  
/**
 * @version 1.0 11/09/98
 */
public class MultiLineHeaderExample extends JFrame {
  MultiLineHeaderExample() {
    super( "Multi-Line Header Example" );
 
    DefaultTableModel dm = new DefaultTableModel();
    dm.setDataVector(new Object[][]{{"a","b","c"},
                                    {"A","B","C"}},
                     new Object[]{"1stnalpha","2ndnbeta","3rdngamma"});
 
    JTable table = new JTable( dm );
    MultiLineHeaderRenderer renderer = new MultiLineHeaderRenderer();
    Enumeration enum = table.getColumnModel().getColumns();
    while (enum.hasMoreElements()) {
      ((TableColumn)enum.nextElement()).setHeaderRenderer(renderer);
    }   
    JScrollPane scroll = new JScrollPane( table );
    getContentPane().add( scroll );
    setSize( 400, 110 );
    setVisible(true);
  }
 
  public static void main(String[] args) {
    MultiLineHeaderExample frame = new MultiLineHeaderExample();
    frame.addWindowListener( new WindowAdapter() {
      public void windowClosing( WindowEvent e ) {
        System.exit(0);
      }
    });
  }
}

MultiLineHeaderRenderer.java:

import java.io.*;
import java.util.*;
import java.awt.*;
import javax.swing.*;
import javax.swing.table.*;


/**
 * @version 1.0 11/09/98
 */
public class MultiLineHeaderRenderer extends JList implements TableCellRenderer {
  public MultiLineHeaderRenderer() {
    setOpaque(true);
    setForeground(UIManager.getColor("TableHeader.foreground"));
    setBackground(UIManager.getColor("TableHeader.background"));
    setBorder(UIManager.getBorder("TableHeader.cellBorder"));
    ListCellRenderer renderer = getCellRenderer();
    ((JLabel)renderer).setHorizontalAlignment(JLabel.CENTER);
    setCellRenderer(renderer);
  }
 
  public Component getTableCellRendererComponent(JTable table, Object value,
                   boolean isSelected, boolean hasFocus, int row, int column) {
    setFont(table.getFont());
    String str = (value == null) ? "" : value.toString();
    BufferedReader br = new BufferedReader(new StringReader(str));
    String line;
    Vector v = new Vector();
    try {
      while ((line = br.readLine()) != null) {
        v.addElement(line);
      }
    } catch (IOException ex) {
      ex.printStackTrace();
    }
    setListData(v);
    return this;
  }
}

Creating a rounded JButton

Extend the JButton class and override the paintComponent and paintBorder methods. To ensure that only mouse-clicks are accepted within the round shape, override the contains method too.
Main.java:

import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;
import java.awt.*;
   
public class Main extends JFrame implements ActionListener {
   JList list; 
 
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      RoundButton rbutton = new RoundButton("Click me!");
      rbutton.addActionListener(this);
      getContentPane().add(BorderLayout.CENTER, rbutton);
  
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      setSize(400, 400);
   }
 
   public void actionPerformed(ActionEvent ae) {
      System.out.println("Your pressed the "" + ae.getActionCommand() + "" button");
   }
   
   public static void main(String[] args) {
      (new Main()).show();
   }
}
 
class RoundButton extends JButton
{
   // for mouse detection purposes
   Shape shape;

   public RoundButton(String label) {
      super(label);
      // allows us to paint a round background
      // if true, it would be rectangular
      setContentAreaFilled(false);
   }
 
   protected void paintComponent(Graphics g) {
      // if the button is pressed and ready to be released
      if (getModel().isArmed()) {
         g.setColor(Color.lightGray);
      } else {
         g.setColor(getBackground());
      }
 
      g.fillOval(0, 0, getSize().width-1, getSize().height-1);
 
      super.paintComponent(g);
   }
 
   // paint a round border as opposed to a rectangular one
   protected void paintBorder(Graphics g) {
      g.setColor(getForeground());
      g.drawOval(0, 0, getSize().width-1, getSize().height-1);
   }
 
   // only clicks within the round shape should be accepted
   public boolean contains(int x, int y) {
      if (shape == null || !shape.getBounds().equals(getBounds())) {
         shape = new Ellipse2D.Float(0, 0, getWidth(), getHeight());
      }
 
      return shape.contains(x, y);
   }
}

Creating a JTextField as an element of JList

This example uses an EditableJList, a custom JList that only allows an EditableJList.EditableListModel as model. Our EditableListModel can only contain JTextComponents (JTextField, JTextArea, …) items.
The behavior is such that when double-clicking on the JList, the selected item is detected using the method locationToIndex and a border is added to it. The border will be removed when the textfield looses focus. To ensure that the JList element is being updated while editing the textfield, every DocumentEvent is captured and fireContentsChanged is called.
Main.java:

import javax.swing.event.*;
import javax.swing.text.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.awt.*;
  
public class Main extends JFrame {
 
   public Main() {
      getContentPane().setLayout(new BorderLayout());
 
      EditableJList.EditableListModel listModel = new EditableJList.EditableListModel();
 
      // populate listmodel
      Random r = new Random();
      for (int i=0; i&lt;50; i++) {
         String item = &quot;list item # &quot; + (Math.abs(r.nextInt()) % 100);
         JTextField tc = new JTextField(item);
//         JTextArea tc = new JTextArea(item);
//         JEditorPane tc = new JEditorPane(&quot;text/html&quot;, &quot;&lt;h3&gt;&quot; + item + &quot;&lt;/h3&gt;&quot;);
         listModel.addElement(tc);
      }
 
      EditableJList list = new EditableJList(listModel); 
      getContentPane().add(BorderLayout.CENTER, new JScrollPane(list));    
  
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      pack();
   }
 
   public static void main(String[] args) {
      (new Main()).show();
   }
}
 
class EditableJList extends JList {
   public EditableJList(EditableListModel listModel) {
      setModel(listModel);
      addMouseListener();
 
      // set our custom cell renderer
      setCellRenderer(new TextComponentCellRenderer()); 
   }
 
   private void addMouseListener() {  
      MouseListener mouseListener = new MouseAdapter() {
         public void mouseClicked(MouseEvent e) {
            if (e.getClickCount() == 2) {
               EditableListModel listModel = (EditableListModel) getModel();
 
               // determine the clicked item
               int index = locationToIndex(e.getPoint());
               Object value = listModel.getElementAt(index);
               final JTextComponent tc = (JTextComponent) value;
 
               // set the appropriate border for editing 
               String classname = tc.getClass().getName().toString();
               classname = classname.substring(classname.lastIndexOf(&quot;.&quot;));
               tc.setBorder(UIManager.getBorder(classname + &quot;border&quot;));
 
               // make this border appear in the JList
               listModel.updateItem(index);
 
               tc.addFocusListener(new FocusListener() {
                  public void focusGained(FocusEvent fe) {
                     // no selection color desired when editing a JTextComponent
                     clearSelection();
                  }
 
                  public void focusLost(FocusEvent fe) {
                     // remove the border again when stopped editing
                     tc.setBorder(null);
                  }
               });
 
               // request the focus on this component to be able to edit it
               tc.requestFocus();
 
               // listen to all key events on the JTextComponent and update the 
               // JList item every time.  Without this, you won't see the changes.           
               tc.getDocument().addDocumentListener(new UpdateListDocumentListener(listModel, index));
            }
         }
      };
 
      addMouseListener(mouseListener);
   }
 
   // DocumentListener that takes care of updating a JList item
   // when editing it.  Calls updateItem on our custom EditableListModel
   private class UpdateListDocumentListener implements DocumentListener {
      private EditableListModel elm;
      private int index;
 
      public UpdateListDocumentListener(EditableListModel elm, int index) {
         this.elm = elm;
         this.index = index;
      }
 
      public void insertUpdate(DocumentEvent e) {
         elm.updateItem(index);
      }
 
      public void removeUpdate(DocumentEvent e) {
         elm.updateItem(index);
      }
 
      public void changedUpdate(DocumentEvent e) {
         elm.updateItem(index);
      }
   }
 
   private class TextComponentCellRenderer implements ListCellRenderer {
      public Component getListCellRendererComponent(
         JList list,
         Object value,            // value to display
         int index,               // cell index
         boolean isSelected,      // is the cell selected
         boolean cellHasFocus)    // the list and the cell have the focus
      {
         JTextComponent tc = (JTextComponent) value;
         if (isSelected) {
            tc.setBackground(list.getSelectionBackground());
            tc.setForeground(list.getSelectionForeground());
         }
         else {
            tc.setBackground(list.getBackground());
            tc.setForeground(list.getForeground());
         }
 
         tc.setEnabled(list.isEnabled());
         tc.setFont(list.getFont());
         tc.setBorder(null);
 
         return (Component) value;
      }
   }
 
   public static class EditableListModel extends DefaultListModel {
      public void updateItem(int index) {
         fireContentsChanged(this, index, index);
      }

      public void addElement(JTextComponent tc) {
         super.addElement(tc);
      }
   }
}

Creating an editable JList

Courtesy of Nobuo Tamemasa (http://www2.gol.com/users/tame/swing/examples/JTableExamples1.html)



EditableListExample.java:

import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
 
/**
 * @version 1.0 12/24/98
 */
public class EditableListExample extends JFrame {
 
  public EditableListExample() {
    super(&quot;Editable List Example&quot;);
    
    String[] data = {&quot;a&quot;,&quot;b&quot;,&quot;c&quot;,&quot;d&quot;,&quot;e&quot;,&quot;f&quot;,&quot;g&quot;};
    
    JList list = new JList( data );
    JScrollPane scrollList = new JScrollPane( list );
    scrollList.setMinimumSize(new Dimension(100,80));
    Box listBox = new Box(BoxLayout.Y_AXIS);
    listBox.add(scrollList);
    listBox.add(new JLabel(&quot;JList&quot;));
         
    DefaultTableModel dm = new DefaultTableModel();
    Vector dummyHeader = new Vector();
    dummyHeader.addElement(&quot;&quot;);
    dm.setDataVector(
      strArray2Vector(data),
      dummyHeader);
    JTable table = new JTable( dm );
    table.setShowGrid(false);
    table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    JScrollPane scrollTable = new JScrollPane( table );
    scrollTable.setColumnHeader(null);
    scrollTable.setMinimumSize(new Dimension(100,80));
    Box tableBox = new Box(BoxLayout.Y_AXIS);
    tableBox.add(scrollTable);
    tableBox.add(new JLabel(&quot;JTable&quot;));
    
    Container c = getContentPane();
    c.setLayout(new BoxLayout(c, BoxLayout.X_AXIS));
    c.add(listBox);
    c.add(new JSeparator(SwingConstants.VERTICAL));
    //c.add(new JLabel(&quot;test&quot;));
    //c.add(new JSeparator(SwingConstants.HORIZONTAL));
    c.add(tableBox);
    setSize( 220, 130 );
    setVisible(true);
  } 
   
  private Vector strArray2Vector(String[] str) {
    Vector vector = new Vector();
    for (int i=0;i&lt;str.length;i++) {
      Vector v = new Vector();
      v.addElement(str[i]);
      vector.addElement(v);
    }
    return vector;
  }

  public static void main(String[] args) {
    final EditableListExample frame = new EditableListExample();
    frame.addWindowListener( new WindowAdapter() {
      public void windowClosing( WindowEvent e ) {
        System.exit(0);
      }
    });
  }
}

Center a text over a JButton’s icon

Use the JButton’s methods setHorizontalTextPosition and setVerticalTextPosition.
Main.java:

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
   
public class Main extends JFrame implements ActionListener {
   JList list; 
 
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      JButton fbutton = new JButton("Text Over Image", new ImageIcon("female.gif"));
      fbutton.addActionListener(this);
      fbutton.setVerticalTextPosition(SwingConstants.CENTER);
      fbutton.setHorizontalTextPosition(SwingConstants.CENTER); 
 
      getContentPane().add(BorderLayout.CENTER, fbutton);
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      setSize(400, 400);
   }
 
   public void actionPerformed(ActionEvent ae) {
      System.out.println("Your pressed the "" + ae.getActionCommand() + "" button");
   }
   
   public static void main(String[] args) {
      (new Main()).show();
   }
}

Detecting a double-click on an element in a JList

For detecting double-clicking, add a MouseListener and catch the MouseEvents where clickCount is equal to 2.

Here’s an example:

import javax.swing.event.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.awt.*;
  
public class Main extends JFrame {
 
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      Vector v = new Vector();
      for (int i=0; i<50; i++) {
         v.addElement("Item #" + i);
      }
      getContentPane().add(new JLabel("Double-clicked on: "));
      final JTextField dblTextField = new JTextField(15);
      getContentPane().add(dblTextField);
      final JList list = new JList(v);
 
      // catch double-click events
      list.addMouseListener(new MouseAdapter() {
         public void mouseClicked(MouseEvent me) {
            if (me.getClickCount() == 2) {
               dblTextField.setText(""+list.getSelectedValue()); 
            }
         }
      });
 
      getContentPane().add(new JScrollPane(list));    
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      setSize(200, 300);
   }
   
   public static void main(String[] args) {
      (new Main()).show();
   }
}

Creating a JList with icons and text

Main.java:

import java.awt.image.*;
import javax.swing.*;
import java.util.*;
import java.awt.*;
  
public class Main 
{
   public static void main(String args[]) {
      JFrame frame = new JFrame("JList ImageIcon Demonstration");
 
      DefaultListModel dlm = new DefaultListModel();
      dlm.addElement(new ListEntry("Audio", new ImageIcon("audio.gif")));
      dlm.addElement(new ListEntry("Control Panel", new ImageIcon("controlpanel.gif")));
      dlm.addElement(new ListEntry("Folder", new ImageIcon("folder.gif")));
      dlm.addElement(new ListEntry("Local Disk (C:)", new ImageIcon("mycomp.gif")));
      dlm.addElement(new ListEntry("doc on '192.168.0.1' (Z:)", new ImageIcon("network.gif")));
 
      JList list = new JList(dlm);
      list.setCellRenderer(new ListEntryCellRenderer());
         
      frame.getContentPane().add(BorderLayout.CENTER, new JScrollPane(list)); 
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setVisible(true);
   }
}
 
class ListEntry 
{
   private String value;
   private ImageIcon icon;
 
   public ListEntry(String value, ImageIcon icon) {
      this.value = value;
      this.icon = icon;
   }
 
   public String getValue() {
      return value;
   }
 
   public ImageIcon getIcon() {
      return icon;
   }
 
   public String toString() {
      return value;
   }
}
 
class ListEntryCellRenderer
 extends JLabel implements ListCellRenderer
{
   private JLabel label;
 
   public Component getListCellRendererComponent(JList list, Object value,
                                                 int index, boolean isSelected,
                                                 boolean cellHasFocus) {
      ListEntry entry = (ListEntry) value;
 
      setText(value.toString());
      setIcon(entry.getIcon());
  
      if (isSelected) {
         setBackground(list.getSelectionBackground());
         setForeground(list.getSelectionForeground());
      }
      else {
         setBackground(list.getBackground());
         setForeground(list.getForeground());
      } 
 
      setEnabled(list.isEnabled());
      setFont(list.getFont());
      setOpaque(true);
 
      return this;
   }
}