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();
   }
}

Defining the size of a JComboBox

If you want to change the size of the JComboBox component itself, use:

   combobox.setPreferredSize(new Dimension(x, y));

If you want to have control over the popupwidth and popupheight, extend JComboBox and add the necessary functionality to a custom ComboBoxUI:
Main.java:

import javax.swing.plaf.metal.*;
import javax.swing.plaf.basic.*;
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<20; i++)
         v.addElement("ComboBox Item #" + i);
      SizedJComboBox combobox = new SizedJComboBox(v);
 
      combobox.setPopupWidth(190);
      combobox.setPopupHeight(30);
 
      getContentPane().add(combobox);
  
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent we) {
            System.exit(1);
         }
      });      
   
      setSize(new Dimension(200, 200));
   } 
 
   public static void main(String[] args) throws Exception {
      Main main = new Main();
      main.setVisible(true);
   }
}
 
class SizedJComboBox extends JComboBox {
   protected int popupWidth;
   protected int popupHeight;
 
   public SizedJComboBox(ComboBoxModel aModel) {
      super(aModel);
      setUI(new SizedComboBoxUI());
   }
 
   public SizedJComboBox(final Object[] items) { 
      super(items); 
      setUI(new SizedComboBoxUI());
   } 
 
   public SizedJComboBox(Vector items) { 
      super(items); 
      setUI(new SizedComboBoxUI()); 
   } 
 
   public void setPopupWidth(int width) { 
      popupWidth = width; 
   }
 
   public void setPopupHeight(int height) {
      popupHeight = height;
   } 
 
   public Dimension getPopupSize() { 
      Dimension size = getSize(); 
      if (popupWidth < 1) popupWidth = size.width; 
      return new Dimension(popupWidth, popupHeight); 
   } 
}
 
class SizedComboBoxUI extends MetalComboBoxUI {
   protected ComboPopup createPopup() { 
      BasicComboPopup popup = new BasicComboPopup(comboBox) { 
         public void show() { 
            Dimension popupSize = ((SizedJComboBox) comboBox).getPopupSize(); 
            popupSize.setSize(popupSize.width, popupSize.height < 1 ? getPopupHeightForRowCount(comboBox.getMaximumRowCount()) : popupSize.height); 
            Rectangle popupBounds = computePopupBounds( 0, 
                  comboBox.getBounds().height, popupSize.width, popupSize.height); 
            scroller.setMaximumSize(popupBounds.getSize()); 
            scroller.setPreferredSize(popupBounds.getSize()); 
            scroller.setMinimumSize(popupBounds.getSize()); 
            list.invalidate(); 
            int selectedIndex = comboBox.getSelectedIndex(); 
            if (selectedIndex == -1) { 
               list.clearSelection(); 
            } else { 
               list.setSelectedIndex( selectedIndex ); 
            } 
            list.ensureIndexIsVisible( list.getSelectedIndex() ); 
            setLightWeightPopupEnabled(comboBox.isLightWeightPopupEnabled()); 
 
            show(comboBox, popupBounds.x, popupBounds.y); 
         } 
      }; 
 
      popup.getAccessibleContext().setAccessibleParent(comboBox); 
      return popup; 
   } 
} 

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();
   }
}

Changing the font of a JMenuItem

You can either embed HTML in the JMenuItem’s text, or you can call the method setFont.

Main.java:

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
   
public class Main extends JFrame {
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      JMenuBar menuBar = new JMenuBar();
      JMenu menu = new JMenu("Sex");
      JMenuItem menuItem1 = new JMenuItem("<html><font size=-1>male</font></html>");
      JMenuItem menuItem2 = new JMenuItem("<html><font size=+1>female</font></html>");
      JMenuItem menuItem3 = new JMenuItem("androgyne");
      menuItem3.setFont(new Font("Monospaced", Font.ITALIC, 36));
 
      // add the MenuItems to the Menu 
      menu.add(menuItem1);
      menu.add(menuItem2);
      menu.add(menuItem3);
 
      menuBar.add(menu);
 
      this.setJMenuBar(menuBar); 
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      setSize(400, 400);
   }
 
   public static void main(String[] args) {
      (new Main()).show();
   }
}

Using a JSpinner to walk through dates

Use the SpinnerDateModel.

Main.java:

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
 
public class Main extends JFrame 
{
   public Main()
   {
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent we) {
            System.exit(1);
         }
      });
 
      getContentPane().setLayout(new FlowLayout(FlowLayout.LEFT));
      final SpinnerDateModel spinnerModel = new SpinnerDateModel();
      JSpinner spinner = new JSpinner(spinnerModel);
 
      final JTextField textfield = new JTextField(25);
      JButton button = new JButton(&quot;Get date&quot;);
      button.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent ae) { 
            textfield.setText(&quot;&quot;+spinnerModel.getDate());
         }
      });
 
      getContentPane().add(spinner);
      getContentPane().add(button);
      getContentPane().add(textfield);
   }
  
   public static void main(String args[])
   {
      Main main = new Main();
      main.setSize(300, 150);
      main.setVisible(true);
   }
}

Catching the Enter key event on a JTextField

The following example shows a JDialog with one JTextField. When the Enter key is detected, it will perform a doClick on the OK button.

Main.java:

import javax.swing.event.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
 
public class Main extends JDialog
{
   public Main() {
      getContentPane().setLayout(new GridLayout(2, 1, 20, 20)); 
      final JTextField inputField = new JTextField();
      getContentPane().add(inputField);
 
      final JButton okButton = new JButton("Ok");
      JButton cancelButton = new JButton("Cancel");
      JPanel panel = new JPanel(new GridLayout(1, 2));
      panel.add(okButton);
      panel.add(cancelButton);
 
      getContentPane().add(panel);     
        
      okButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent ae) {
            System.out.println("Ok pressed, textfield = " + inputField.getText());
            System.exit(0);
         }
      });
      cancelButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent ae) {
            System.out.println("Cancel pressed, textfield = " + inputField.getText());
            System.exit(0);
         }
      });
 
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent we) {
            System.exit(0);
         }
      });
 
      // catch the enter key in the JTextField and perform an OK click on the JButton
      inputField.addKeyListener(new KeyAdapter() {
         public void keyPressed(KeyEvent e) {
            if (e.getKeyCode()==KeyEvent.VK_ENTER) {
               okButton.doClick();
            }
         }
      });
 
      pack();
      centerDialog();
   }
 
   public void centerDialog() {
      Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
      int x = (int) ((d.getWidth() - getWidth()) / 2);
      int y = (int) ((d.getHeight() - getHeight()) / 2);
      setLocation(x, y);
   }
 
   public static void main(String []args) {
      Main main = new Main();
      main.setVisible(true);
   }
}

Creating a JLabel with the text underlined

The easiest way is to use the HTML tag u. If you don’t want to use the HTML feature, check out How do I create an underlined JLabel without using HTML?

Main.java:

import java.awt.event.*;
import java.awt.font.*; 
import javax.swing.*;
import java.util.*;
import java.text.*;
import java.awt.*;
   
public class Main extends JFrame {
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      JLabel label = new JLabel("<html><u>Underlined text with HTML</u></html>");
      getContentPane().add(label);
  
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      setSize(300, 200);
   }
 
   public static void main(String[] args) {
      (new Main()).show();
   }
}

Localizing a JColorChooser

With the UIManager class, you have control over the text labels that appear in a default colorchooser. Look at following example. Note that you cannot change the text “Sample Text” of the default preview label (instead, you can create your own with setPreviewPane).

Main.java:

import javax.swing.event.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
 
public class Main extends JFrame {
   public Main() {
      super("JColorChooser Demonstration");
 
      UIManager.put("ColorChooser.swatchesNameText", "My Swatches"); 
      UIManager.put("ColorChooser.swatchesRecentText", "My Recent"); 
      UIManager.put("ColorChooser.hsbNameText", "My HSB"); 
      UIManager.put("ColorChooser.rgbNameText", "My RGB"); 
      UIManager.put("ColorChooser.previewText", "My Preview"); 
      UIManager.put("ColorChooser.rgbRedText", "My Red"); 
      UIManager.put("ColorChooser.rgbGreenText", "My Green"); 
      UIManager.put("ColorChooser.rgbBlueText", "My Blue"); 
  
      getContentPane().setLayout(new FlowLayout()); 
      final JColorChooser colorChooser = new JColorChooser(); 
 
      getContentPane().add(colorChooser);
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent e) {
            System.exit(0);
         }
      });
   }
 
   public static void main(String[] args) {
      Main main = new Main();
      main.pack();
      main.setVisible(true);
   }
}

Creating a JTable with fixed rows

Courtesy of Nobuo Tamemasa (http://www2.gol.com/users/tame/swing/examples/JTableExamples6.html)



FixedRowExample.java:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
import javax.swing.event.*;

/**
 * @version 1.0 03/05/99
 */
public class FixedRowExample extends JFrame {
  Object[][] data;
  Object[] column;
  JTable fixedTable,table;
  private int FIXED_NUM = 2;

  public FixedRowExample() {
    super( "Fixed Row Example" );
    
    data =  new Object[][]{
        {      "a","","","","",""},
        {      "","b","","","",""},
        {      "","","c","","",""},
        {      "","","","d","",""},
        {      "","","","","e",""},
        {      "","","","","","f"},
        {"fixed1","","","","","","",""},
        {"fixed2","","","","","","",""}};
    column = new Object[]{"A","B","C","D","E","F"};
        
    AbstractTableModel    model = new AbstractTableModel() {
      public int getColumnCount() { return column.length; }
      public int getRowCount() { return data.length - FIXED_NUM; }
      public String getColumnName(int col) {
       return (String)column[col]; 
      }
      public Object getValueAt(int row, int col) { 
        return data[row][col]; 
      }
      public void setValueAt(Object obj, int row, int col) { 
        data[row][col] = obj; 
      }
      public boolean CellEditable(int row, int col) { 
        return true; 
      }
    };
    
    AbstractTableModel fixedModel = new AbstractTableModel() {      
      public int getColumnCount() { return column.length; }
      public int getRowCount() { return FIXED_NUM; }
      public Object getValueAt(int row, int col) { 
        return data[row + (data.length - FIXED_NUM)][col]; 
      }
    };
    
    table = new JTable( model );
    table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
    table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    
    fixedTable = new JTable( fixedModel );
    fixedTable.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
    fixedTable.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    
    JScrollPane scroll      = new JScrollPane( table );
    scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);

    
    JScrollPane fixedScroll = new JScrollPane( fixedTable ) {
      public void setColumnHeaderView(Component view) {} // work around
    };                                                   //
                                             // fixedScroll.setColumnHeader(null); 
    
    fixedScroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
    JScrollBar bar = fixedScroll.getVerticalScrollBar();
    JScrollBar dummyBar = new JScrollBar() {
      public void paint(Graphics g) {}
    };
    dummyBar.setPreferredSize(bar.getPreferredSize());
    fixedScroll.setVerticalScrollBar(dummyBar);
    
    final JScrollBar bar1 = scroll.getHorizontalScrollBar();
    JScrollBar bar2 = fixedScroll.getHorizontalScrollBar();
    bar2.addAdjustmentListener(new AdjustmentListener() {
      public void adjustmentValueChanged(AdjustmentEvent e) {
        bar1.setValue(e.getValue());
      }
    });
    
    
    scroll.setPreferredSize(new Dimension(400, 100));
    fixedScroll.setPreferredSize(new Dimension(400, 52));  // Hmm...
    getContentPane().add(     scroll, BorderLayout.CENTER);
    getContentPane().add(fixedScroll, BorderLayout.SOUTH);    
  }

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