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("Get date");
      button.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent ae) { 
            textfield.setText(""+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);
   }
}

Changing the background of a JLabel

Call the method setBackground on your component but don’t forget to set your component to be opaque. A component that is not opaque (default) lets whatever is behind them show through. Their backgrounds are determined by the component that is shown behind them.

Main.java:

import javax.swing.text.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.*;
import java.awt.*;
   
public class Main extends JFrame {
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      JLabel label = new JLabel("Colored label");
      label.setOpaque(true);
      label.setBackground(Color.white);
 
      getContentPane().add(label);     
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      setSize(300, 100);
   }
 
   public static void main(String[] args) {
      (new Main()).show();
   }
}

Creating a vertical JLabel

Code currently works only for 90 or -90 degrees only. It was written to support the answer to the question “How do I create vertically oriented JTable headers”.

Main.java:

import javax.swing.plaf.basic.*;
import javax.swing.border.*;
import javax.swing.text.*;
import java.awt.event.*;
import java.awt.font.*;
import java.awt.geom.*;
import javax.swing.*;
import java.util.*;
import java.awt.*;
 
public class Main extends JFrame
{
   public Main() {
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent we) {
            System.exit(0);
         }
      });
 
      getContentPane().setLayout(new FlowLayout(FlowLayout.LEFT));
 
      JLabel normalLabel = new JLabel("Normal JLabel");
      normalLabel.setBorder(LineBorder.createBlackLineBorder());
 
      JLabel verticalLabel1 = new JLabel("Vertical JLabel, 90 degrees");
      verticalLabel1.setUI(new VerticalLabelUI(90));
      verticalLabel1.setBorder(LineBorder.createBlackLineBorder());
 
      JLabel verticalLabel2 = new JLabel("Vertical JLabel, -90 degrees");
      verticalLabel2.setUI(new VerticalLabelUI(-90));
      verticalLabel2.setBorder(LineBorder.createBlackLineBorder());
 
      getContentPane().add(normalLabel);
      getContentPane().add(verticalLabel1);
      getContentPane().add(verticalLabel2);
   }
 
   public static void main(String []args) {
      Main main = new Main();
      main.pack();
      main.setVisible(true);
   }
}
 
class VerticalLabelUI extends BasicLabelUI
{
   protected float degrees;
   private static Rectangle paintIconR = new Rectangle();
   private static Rectangle paintTextR = new Rectangle();
   private static Rectangle paintViewR = new Rectangle();
   private static Insets paintViewInsets = new Insets(0, 0, 0, 0);
 
   VerticalLabelUI(float degrees) {
      this.degrees = degrees;
   }
 
   public Dimension getPreferredSize(JComponent c) {
      Dimension dim = super.getPreferredSize(c);
      return new Dimension( dim.height, dim.width );
   }
 
   public void paint(Graphics g, JComponent c) {
      JLabel label = (JLabel)c;
      String text = label.getText();
      Icon icon = (label.isEnabled()) ? label.getIcon() : label.getDisabledIcon();
 
      if ((icon == null) && (text == null)) {
         return;
      }
 
      FontMetrics fm = g.getFontMetrics();
      paintViewInsets = c.getInsets(paintViewInsets);
 
      paintViewR.x = paintViewInsets.left;
      paintViewR.y = paintViewInsets.top;    	
      paintViewR.height = c.getWidth() - (paintViewInsets.left + paintViewInsets.right);
      paintViewR.width = c.getHeight() - (paintViewInsets.top + paintViewInsets.bottom);
 
      paintIconR.x = paintIconR.y = paintIconR.width = paintIconR.height = 0;
      paintTextR.x = paintTextR.y = paintTextR.width = paintTextR.height = 0;
 
      String clippedText = 
            layoutCL(label, fm, text, icon, paintViewR, paintIconR, paintTextR);
 
      Graphics2D g2d = (Graphics2D) g;
      // save old value
      AffineTransform affineTransformOld = g2d.getTransform();
 
      double radians = degrees * (Math.PI / 180); 
      g2d.rotate(radians);
      Dimension d = getPreferredSize(c);      
      if (degrees == 90) {
         g2d.translate(0,-d.width);
      } 
      else {
         g2d.translate(-d.height, 0);
      }
 
      if (icon != null) {
         icon.paintIcon(c, g, paintIconR.x, paintIconR.y);
      }
 
      if (text != null) {
         View v = (View) c.getClientProperty(BasicHTML.propertyKey);
         if (v != null) {
            v.paint(g, paintTextR);
         }
         else {
            int textX = paintTextR.x;
            int textY = paintTextR.y + fm.getAscent();
 
            if (label.isEnabled()) {
               paintEnabledText(label, g, clippedText, textX, textY);
            }
            else {
               paintDisabledText(label, g, clippedText, textX, textY);
            }
         }
      } 	
    	
      g2d.setTransform(affineTransformOld);
   }
}

Add a background image to a JTable

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.table.*;
 
public class BackgroundTable 
{ 
   public static void main(String[] args) {
      JFrame frame = new JFrame("Table Example"); 
      frame.addWindowListener( new WindowAdapter() { 
         public void windowClosing(WindowEvent e) 
         { 
            Window w = e.getWindow(); 
            w.setVisible(false); 
            w.dispose(); 
            System.exit(0); 
         } 
      }); 
 
      JTable imTable = new JTable(35, 3) { 
         public Component prepareRenderer(TableCellRenderer renderer, int row, int column) 
         { 
            Component c = super.prepareRenderer( renderer, row, column); 
            // We want renderer component to be 
            //transparent so background image is visible 
            if( c instanceof JComponent ) 
               ((JComponent)c).setOpaque(false); 
            return c; 
         }
   
         public void paint( Graphics g ) 
         { 
            ImageIcon image = new ImageIcon("FIREFALL.gif"); 
            // tile the background image 
            Dimension d = getSize(); 
            for( int x = 0; x < d.width; x += image.getIconWidth() ) 
            for( int y = 0; y < d.height; y += image.getIconHeight() ) 
            g.drawImage( image.getImage(), x, y, null, null ); 
            // Now let the paint do its usual work 
            super.paint(g); 
         } 
      }; 
 
      //make the table transparent 
      imTable.setOpaque(false); 
 
      JScrollPane jsp = new JScrollPane(imTable); 
      frame.getContentPane().add(jsp); 
 
      frame.pack(); 
      frame.show(); 
   } 
}

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);
  }
}

Embedding a JTextArea in a JTable cell

JTextAreaTableExample.java:

import javax.swing.border.*;
import javax.swing.event.*;
import javax.swing.table.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.awt.*;
  
public class JTextAreaTableExample extends JFrame {
 
  public JTextAreaTableExample() {
    super( "JTextAreaTableExample Example" );
  
    DefaultTableModel dtm = new DefaultTableModel() {
       // make first cell uneditable
       public boolean isCellEditable(int row, int column)
       {
          return !(column == 0);
       }
    };
 
    dtm.setDataVector(new Object[][]{{ "JTextArea1", "This is a testnon long linesn" },
                                     { "JTextArea2", "Hello, world!" }},
                      new Object[]{ "String","JTextArea"});
                     
    JTable table = new JTable(dtm);
    table.getColumn("JTextArea").setCellRenderer(new TextAreaRenderer());
    table.getColumn("JTextArea").setCellEditor(new TextAreaEditor());
 
    table.setRowHeight(80);
    JScrollPane scroll = new JScrollPane(table);
    getContentPane().add(scroll);
 
    setSize( 400, 250 );
    setVisible(true);
  }
 
  public static void main(String[] args) {
    JTextAreaTableExample frame = new JTextAreaTableExample();
    frame.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
  }
}
  
class TextAreaRenderer extends JScrollPane implements TableCellRenderer
{
   JTextArea textarea;
 
   public TextAreaRenderer() {
      textarea = new JTextArea();
      textarea.setLineWrap(true);
      textarea.setWrapStyleWord(true);
      textarea.setBorder(new TitledBorder("This is a JTextArea"));
      getViewport().add(textarea);
   }
 
   public Component getTableCellRendererComponent(JTable table, Object value,
                                  boolean isSelected, boolean hasFocus,
                                  int row, int column)
   {
      if (isSelected) {
         setForeground(table.getSelectionForeground());
         setBackground(table.getSelectionBackground());
         textarea.setForeground(table.getSelectionForeground());
         textarea.setBackground(table.getSelectionBackground());
      } else {
         setForeground(table.getForeground());
         setBackground(table.getBackground());
         textarea.setForeground(table.getForeground());
         textarea.setBackground(table.getBackground());
      }
 
      textarea.setText((String) value); 
      textarea.setCaretPosition(0);
      return this;
   }
}
 
class TextAreaEditor extends DefaultCellEditor {
   protected JScrollPane scrollpane;
   protected JTextArea textarea; 
 
   public TextAreaEditor() {
      super(new JCheckBox());
      scrollpane = new JScrollPane();
      textarea = new JTextArea();  
      textarea.setLineWrap(true);
      textarea.setWrapStyleWord(true);
      textarea.setBorder(new TitledBorder("This is a JTextArea"));
      scrollpane.getViewport().add(textarea);
   }
 
   public Component getTableCellEditorComponent(JTable table, Object value,
                                   boolean isSelected, int row, int column) {
      textarea.setText((String) value);
 
      return scrollpane;
   }
 
   public Object getCellEditorValue() {
      return textarea.getText();
   }
}

Getting an event when a selection on my JTree changes

Implement a TreeSelectionListener and add it using addTreeSelectionListener.

Main.java:

import javax.swing.*;
import javax.swing.tree.*;
import javax.swing.event.*;
import java.awt.*;
import java.net.*;
import java.awt.event.*;
 
public class Main extends JFrame
{
   public Main() {
      DefaultMutableTreeNode root = createNodes();
      JTree tree = new JTree(root);
 
      tree.addTreeSelectionListener(new TreeSelectionListener() {
         public void valueChanged(TreeSelectionEvent e) {         
            TreePath path = e.getPath();
            System.out.println(path.getLastPathComponent());     
         }
      });
 
      getContentPane().add(new JScrollPane(tree));
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent we) {
            System.exit(0);
         }
      });
   }
 
   public static DefaultMutableTreeNode createNodes() {
      DefaultMutableTreeNode root = new DefaultMutableTreeNode("Java");
      
      DefaultMutableTreeNode j2se = new DefaultMutableTreeNode("J2SE");
      DefaultMutableTreeNode j2ee = new DefaultMutableTreeNode("J2EE");
      DefaultMutableTreeNode j2me = new DefaultMutableTreeNode("J2ME");
 
      j2se.add(new DefaultMutableTreeNode("http://java.sun.com/j2se/"));
      j2ee.add(new DefaultMutableTreeNode("http://java.sun.com/j2ee/"));
      j2me.add(new DefaultMutableTreeNode("http://java.sun.com/j2me/"));
 
      root.add(j2se);
      root.add(j2ee);
      root.add(j2me);
 
      return root;
   }
 
   public static void main(String []args) {
      Main main = new Main();
      main.setSize(400, 400);
      main.setVisible(true);
   }
}

Binding a control key to a JTextArea component

In the following example, the CTRL-L key is mapped to an Action when pressed in the JTextArea.

Main.java:

import javax.swing.event.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
 
public class Main extends JFrame
{
   public Main() {
      JTextArea ta = new JTextArea();
      getContentPane().add(new JScrollPane(ta));
 
      Action gotoLineAction = new AbstractAction("gotoline") {
         public void actionPerformed(ActionEvent ae) {
            String value = JOptionPane.showInputDialog("Goto line no");
            System.out.println("Include functionality here to goto line " + value); 
         }
      };
 
      ta.getInputMap().put(KeyStroke.getKeyStroke("control L"), "gotoline");
      ta.getActionMap().put(gotoLineAction.getValue(Action.NAME), gotoLineAction);
  
      ta.setText("Press CTRL-L!");
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent we) {
            System.exit(1);
         }
      });
   }
 
   public static void main(String []args) {
      Main main = new Main();
      main.setSize(400, 400);
      main.setVisible(true);
   }
}

Changing the color of the lines between JTable header cells

Main.java:

import javax.swing.plaf.basic.*;
import javax.swing.border.*;
import javax.swing.*;
import javax.swing.table.*;
import java.awt.*;
import java.awt.event.*;
 
public class Main extends JFrame 
{
   public Main() {
      String[] header = {"column #1","column #2","column #3", "column #4"};
      String[][] data = {{"1","2","3","4"},
                         {"5","6","7","8"}};
 
      JTable table = new JTable(data, header);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      getContentPane().add(new JScrollPane(table));
 
      MyHeaderRenderer renderer = new MyHeaderRenderer();
      System.out.println(table.getTableHeader().getDefaultRenderer());
      table.getTableHeader().setDefaultRenderer(renderer);
       
      setSize(300,200);
   } 

 
   public static void main( String args[] ) { 
      Main main = new Main();
      main.setVisible(true);
   }
}
 
class MyHeaderRenderer extends DefaultTableCellRenderer 
{
   private static LineBorder border = new LeftColorLineBorder((Color) UIManager.get("Button.focus"));
 
   public java.awt.Component getTableCellRendererComponent(JTable table, Object value,
                                 boolean selected, boolean focus, int row, int col) {
      Component c = super.getTableCellRendererComponent(table, value, selected, focus, row, col);
 


      setHorizontalAlignment(JLabel.CENTER);
      setBorder(border);
      return c;
   }
}
 
class LeftColorLineBorder extends LineBorder
{
   public LeftColorLineBorder(Color color) {
      super(color, 1, false);
   }
 
   public LeftColorLineBorder(Color color, int thickness) {
      super(color, thickness, false);
   }
 
   public LeftColorLineBorder(Color color, int thickness, boolean roundedCorners) {
      super(color, thickness, roundedCorners);
   }
   
   public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
      super.paintBorder(c, g, x, y, width, height);
      g.setColor(Color.black);
      g.fillRect(x, y, x+4, y+height);
      g.fillRect(x+width-4, y, x+width, y+height);
   }
}