Java by API/javax.swing/JPanel

extends JPanel

  
import java.awt.Color;
import java.awt.Graphics;
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainClass extends JPanel {
  Color color;
  public MainClass(Color color) {
    this.color = color;
  }
  public void paintComponent(Graphics g) {
    int width = getWidth();
    int height = getHeight();
    g.setColor(color);
    g.drawOval(0, 0, width, height);
  }
  public static void main(String args[]) {
    JFrame frame = new JFrame("Oval Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new GridLayout(2, 2));
    Color colors[] = { Color.RED, Color.BLUE, Color.GREEN, Color.YELLOW };
    for (int i = 0; i < 4; i++) {
      MainClass panel = new MainClass(colors[i]);
      frame.add(panel);
    }
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}

JPanel: addAncestorListener(AncestorListener lis)

  
import javax.swing.JFrame;
import javax.swing.event.AncestorEvent;
import javax.swing.event.AncestorListener;
public class MainClass {
  public static void main(String[] a) {
    JFrame frame = new JFrame("Ancestor Sampler");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    AncestorListener ancestorListener = new AncestorListener() {
      public void ancestorAdded(AncestorEvent ancestorEvent) {
        System.out.println("Added");
      }
      public void ancestorMoved(AncestorEvent ancestorEvent) {
        System.out.println("Moved");
      }
      public void ancestorRemoved(AncestorEvent ancestorEvent) {
        System.out.println("Removed");
      }
    };
    frame.getRootPane().addAncestorListener(ancestorListener);
    frame.setSize(300, 200);
    frame.setVisible(true);
    frame.getRootPane().setVisible(false);
    frame.getRootPane().setVisible(true);
  }
}

JPanel: addContainerListener(ContainerListener l)

  
import java.awt.event.ContainerEvent;
import java.awt.event.ContainerListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main {
  public static void main(String[] a) {
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel buttonPanel = new JPanel();
    buttonPanel.addContainerListener(new ContainerListener() {
      public void componentAdded(ContainerEvent e) {
        displayMessage(" added to ", e);
      }
      public void componentRemoved(ContainerEvent e) {
        displayMessage(" removed from ", e);
      }
      void displayMessage(String action, ContainerEvent e) {
        System.out.println(((JButton) e.getChild()).getText() + " was" + action
            + e.getContainer().getClass().getName());
      }
    });
    buttonPanel.add(new JButton("A"));
    frame.add(buttonPanel);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}

JPanel: addKeyListener(KeyListener l)

  
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main extends JPanel implements KeyListener {
  private Point startPoint = new Point(0, 0);
  private Point endPoint = new Point(0, 0);
  public Main() {
    addKeyListener(this);
  }
  public void keyPressed(KeyEvent evt) {
    int keyCode = evt.getKeyCode();
    int d;
    if (evt.isShiftDown())
      d = 5;
    else
      d = 1;
    if (keyCode == KeyEvent.VK_LEFT)
      add(-d, 0);
    else if (keyCode == KeyEvent.VK_RIGHT)
      add(d, 0);
    else if (keyCode == KeyEvent.VK_UP)
      add(0, -d);
    else if (keyCode == KeyEvent.VK_DOWN)
      add(0, d);
  }
  public void keyReleased(KeyEvent evt) {
  }
  public void keyTyped(KeyEvent evt) {
  }
  public boolean isFocusTraversable() {
    return true;
  }
  public void add(int dx, int dy) {
    endPoint.x += dx;
    endPoint.y += dy;
    Graphics g = getGraphics();
    g.drawLine(startPoint.x, startPoint.y, endPoint.x, endPoint.y);
    g.dispose();
    startPoint.x = endPoint.x;
    startPoint.y = endPoint.y;
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.setTitle("Sketch");
    frame.setSize(300, 200);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container contentPane = frame.getContentPane();
    contentPane.add(new Main());
    frame.setVisible(true);
  }
}

JPanel: addMouseListener(MouseListener mous)

  
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainClass extends JPanel {
  public MainClass() {
      addMouseListener(new MouseAdapter() { 
          public void mousePressed(MouseEvent me) { 
            System.out.println(me); 
          } 
        }); 
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.getContentPane().add(new MainClass());
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    
    frame.setSize(200, 200);
    frame.setVisible(true);
  }
}

JPanel: addMouseMotionListener(MouseMotionListener lis)

  
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainClass {
  public static void main(String[] args) {
    JFrame aWindow = new JFrame();
    aWindow.setBounds(200, 200, 200, 200);
    aWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container content = aWindow.getContentPane();
    content.add(new MouseMotionEvents());
    aWindow.setVisible(true);
  }
}
class MouseMotionEvents extends JPanel implements MouseListener,
    MouseMotionListener {
  Point p;
  public MouseMotionEvents() {
    addMouseListener(this);
    addMouseMotionListener(this);
  }
  public void mouseClicked(MouseEvent me) {
  }
  public void mouseEntered(MouseEvent me) {
  }
  public void mouseExited(MouseEvent me) {
  }
  public void mousePressed(MouseEvent me) {
    p = me.getPoint();
    repaint();
  }
  public void mouseReleased(MouseEvent me) {
    p = null;
    repaint();
  }
  public void mouseDragged(MouseEvent me) {
    p = me.getPoint();
    repaint();
  }
  public void mouseMoved(MouseEvent me) {
  }
  public void paint(Graphics g) {
    if (p != null) {
      Dimension d = getSize();
      int xc = d.width / 2;
      int yc = d.height / 2;
      g.drawLine(xc, yc, p.x, p.y);
    }
  }
}

JPanel: getFocusTraversalKeys(int id)

  
import java.awt.AWTKeyStroke;
import java.awt.KeyboardFocusManager;
import java.util.Set;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.KeyStroke;
public class Main {
  public static void main(String[] args) {
    JFrame aWindow = new JFrame("This is a Border Layout");
    aWindow.setBounds(30, 30, 300, 300);
    aWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel p = new JPanel();
    p.add(new JTextField(10));
    p.add(new JTextField(10));
    p.add(new JTextField(10));
    p.add(new JTextField(10));
    p.add(new JTextField(10));
    p.add(new JTextField(10));
    Set<AWTKeyStroke> set = p.getFocusTraversalKeys(KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS);
    //set = new HashSet(set);
    KeyStroke up = KeyStroke.getKeyStroke("A");
    set.add(up);
    System.out.println(set);
    p.setFocusTraversalKeys(KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, set);
    aWindow.add(p);
    aWindow.setVisible(true);
  }
}

JPanel: isFocusCycleRoot()

  
import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Focus Cycle Sample");
    Container contentPane = frame.getContentPane();
    contentPane.setLayout(new GridLayout(3,3));
    for (int i = 0; i < 8; i++) {
      JButton button = new JButton("" + i);
      contentPane.add(button);
    }
    JPanel panel = new FocusCycleConstrainedJPanel();
    panel.setLayout(new GridLayout(1, 3));
    for (int i = 0; i < 3; i++) {
      JButton button = new JButton("" + (i + 3));
      panel.add(button);
    }
    contentPane.add(panel);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}
class FocusCycleConstrainedJPanel extends JPanel {
  public boolean isFocusCycleRoot() {
    return true;
  }
}

JPanel: paintComponent(Graphics g)

  
import java.awt.Color;
import java.awt.Graphics;
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainClass extends JPanel {
  Color color;
  public MainClass(Color color) {
    this.color = color;
  }
  public void paintComponent(Graphics g) {
    int width = getWidth();
    int height = getHeight();
    g.setColor(color);
    g.drawOval(0, 0, width, height);
  }
  public static void main(String args[]) {
    JFrame frame = new JFrame("Oval Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new GridLayout(2, 2));
    Color colors[] = { Color.RED, Color.BLUE, Color.GREEN, Color.YELLOW };
    for (int i = 0; i < 4; i++) {
      MainClass panel = new MainClass(colors[i]);
      frame.add(panel);
    }
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}

JPanel: repaint()

  
import java.awt.Color;
import java.awt.Container;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainClass {
  public static void main(String[] args) {
    JFrame aWindow = new JFrame();
    aWindow.setBounds(200, 200, 200, 200);
    aWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container content = aWindow.getContentPane();
    content.add(new MouseMotionAdapterDemo());
    aWindow.setVisible(true);
  }
}
class MouseMotionAdapterDemo extends JPanel {
  public MouseMotionAdapterDemo() {
    setBackground(Color.white);
    addMouseListener(new Adapter1(this));
    addMouseMotionListener(new Adapter2(this));
  }
}
class Adapter1 extends MouseAdapter {
  MouseMotionAdapterDemo mmad;
  public Adapter1(MouseMotionAdapterDemo mmad) {
    this.mmad = mmad;
  }
  public void mouseReleased(MouseEvent me) {
    mmad.setBackground(Color.white);
    mmad.repaint();
  }
}
class Adapter2 extends MouseMotionAdapter {
  MouseMotionAdapterDemo mmad;
  public Adapter2(MouseMotionAdapterDemo mmad) {
    this.mmad = mmad;
  }
  public void mouseDragged(MouseEvent me) {
    mmad.setBackground(Color.cyan);
    mmad.repaint();
  }
}

JPanel: setBackground(Color c)

  
import java.awt.Color;
import java.awt.Container;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainClass {
  public static void main(String[] args) {
    JFrame aWindow = new JFrame();
    aWindow.setBounds(200, 200, 200, 200);
    aWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container content = aWindow.getContentPane();
    content.add(new MouseMotionAdapterDemo());
    aWindow.setVisible(true);
  }
}
class MouseMotionAdapterDemo extends JPanel {
  public MouseMotionAdapterDemo() {
    setBackground(Color.white);
    addMouseListener(new Adapter1(this));
    addMouseMotionListener(new Adapter2(this));
  }
}
class Adapter1 extends MouseAdapter {
  MouseMotionAdapterDemo mmad;
  public Adapter1(MouseMotionAdapterDemo mmad) {
    this.mmad = mmad;
  }
  public void mouseReleased(MouseEvent me) {
    mmad.setBackground(Color.white);
    mmad.repaint();
  }
}
class Adapter2 extends MouseMotionAdapter {
  MouseMotionAdapterDemo mmad;
  public Adapter2(MouseMotionAdapterDemo mmad) {
    this.mmad = mmad;
  }
  public void mouseDragged(MouseEvent me) {
    mmad.setBackground(Color.cyan);
    mmad.repaint();
  }
}

JPanel: setBorder(Border border)

  
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Main extends JFrame {
  public static void main(String[] args) {
    String lyrics = "<html>Line<br>line<br>line</html>";
    JPanel panel = new JPanel();
    panel.setLayout(new BorderLayout(10, 10));
    JLabel label = new JLabel(lyrics);
    label.setFont(new Font("Georgia", Font.PLAIN, 14));
    label.setForeground(new Color(50, 50, 25));
    panel.add(label, BorderLayout.CENTER);
    panel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
    JFrame f = new JFrame();
    f.add(panel);
    f.pack();
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
  }
}

JPanel: setComponentPopupMenu(JPopupMenu popup)

  
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.JTextArea;
import javax.swing.JTextField;
public class Main implements ActionListener {
  JTextArea textArea = new JTextArea();
  public Main() {
    final JPopupMenu contextMenu = new JPopupMenu("Edit");
    contextMenu.add(makeMenuItem("Save"));
    contextMenu.add(makeMenuItem("Save As"));
    contextMenu.add(makeMenuItem("Close"));
    JFrame frame = new JFrame();
    JPanel panel = new JPanel();
    panel.setLayout(new BorderLayout());
    frame.add(panel);
    panel.setComponentPopupMenu(contextMenu);
    textArea.setInheritsPopupMenu(true);
    panel.add(BorderLayout.CENTER, textArea);
    JTextField textField = new JTextField();
    textField.setInheritsPopupMenu(true);
    panel.add(BorderLayout.SOUTH, textField);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(400, 200);
    frame.setVisible(true);
  }
  public void actionPerformed(ActionEvent e) {
    textArea.append(e.getActionCommand() + "\n");
  }
  private JMenuItem makeMenuItem(String label) {
    JMenuItem item = new JMenuItem(label);
    item.addActionListener(this);
    return item;
  }
  public static void main(String[] args) {
    new Main();
  }
}

JPanel: setFocusCycleRoot(boolean value)

  
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainClass {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Focus Cycle Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new GridLayout(3,3));
    for (int i = 0; i < 3; i++) {
      JButton button = new JButton("" + i);
      frame.add(button);
    }
    JPanel panel = new JPanel();
    panel.setFocusCycleRoot(true);
    panel.setFocusTraversalPolicyProvider(true);
    panel.setLayout(new GridLayout(1, 3));
    for (int i = 0; i < 3; i++) {
      JButton button = new JButton("" + (i + 3));
      panel.add(button);
    }
    frame.add(panel);
    for (int i = 0; i < 3; i++) {
      JButton button = new JButton("" + (i + 6));
      frame.add(button);
    }
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}

JPanel: setFocusTraversalPolicyProvider(boolean value)

  
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainClass {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Focus Cycle Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new GridLayout(3,3));
    for (int i = 0; i < 3; i++) {
      JButton button = new JButton("" + i);
      frame.add(button);
    }
    JPanel panel = new JPanel();
    panel.setFocusCycleRoot(true);
    panel.setFocusTraversalPolicyProvider(true);
    panel.setLayout(new GridLayout(1, 3));
    for (int i = 0; i < 3; i++) {
      JButton button = new JButton("" + (i + 3));
      panel.add(button);
    }
    frame.add(panel);
    for (int i = 0; i < 3; i++) {
      JButton button = new JButton("" + (i + 6));
      frame.add(button);
    }
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}

JPanel: setLayout(null)

  
import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
public class MainClass extends JPanel {
  public MainClass() {
    JRadioButton radMarriedYes = new JRadioButton("Yes?", true);
    JRadioButton radMarriedNo = new JRadioButton("No?", false);
    JRadioButton radGolfYes = new JRadioButton("Yes?", false);
    JRadioButton radGolfNo = new JRadioButton("No?", true);
    ButtonGroup radioGroup1 = new ButtonGroup();
    ButtonGroup radioGroup2 = new ButtonGroup();
    setLayout(null);
    add(radMarriedYes);
    add(radMarriedNo);
    add(radGolfYes);
    add(radGolfNo);
    radioGroup1.add(radMarriedYes);
    radioGroup1.add(radMarriedNo);
    radioGroup2.add(radGolfYes);
    radioGroup2.add(radGolfNo);
    radMarriedYes.setBounds(30, 50, 50, 20);
    radMarriedNo.setBounds(30, 80, 50, 20);
    radGolfYes.setBounds(150, 50, 50, 20);
    radGolfNo.setBounds(150, 80, 50, 20);
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.getContentPane().add(new MainClass());
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(200, 200);
    frame.setVisible(true);
  }
}

JPanel: setOpaque(boolean isOpaque)

  
import java.awt.Color;
import java.awt.FlowLayout;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainClass extends JFrame {
  public MainClass() {
    super("Opaque JPanel Demo");
    setSize(400, 200);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    JPanel opaque = createNested(true);
    JPanel notOpaque = createNested(false);
    getContentPane().setLayout(new FlowLayout());
    getContentPane().add(opaque);
    getContentPane().add(notOpaque);
  }
  public static void main(String[] args) {
    MainClass oe = new MainClass();
    oe.setVisible(true);
  }
  public JPanel createNested(boolean opaque) {
    JPanel outer = new JPanel(new FlowLayout());
    JPanel inner = new JPanel(new FlowLayout());
    outer.setBackground(Color.white);
    inner.setBackground(Color.black);
    inner.setOpaque(opaque);
    inner.setBorder(BorderFactory.createLineBorder(Color.gray));
    inner.add(new JButton("Button"));
    outer.add(inner);
    return outer;
  }
}

JPanel: setPreferredSize(Dimension preferredSize)

  
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.border.Border;
public class Main {
  public static void main(String args[]) {
    JFrame f = new JFrame("Label Demo");
    f.setLayout(new FlowLayout());
    f.setSize(200, 360);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    
    JLabel label= new JLabel("asdf");
    Border border = BorderFactory.createLineBorder(Color.BLACK);
    label.setBorder(border);
    label.setPreferredSize(new Dimension(150, 100));
    f.add(label);
    f.setVisible(true);
  }
}

JPanel: setToolTipText(String htmlString)

  
import java.awt.BorderLayout;
import java.awt.Color;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JToolTip;
public class MainClass {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Tooltip");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel = new JPanel();
    panel.setToolTipText("<HtMl>Tooltip<br>Message");
    frame.add(panel, BorderLayout.CENTER);
    JButton button = new JButton("Hello, World") {
      public JToolTip createToolTip() {
        JToolTip tip = super.createToolTip();
        tip.setBackground(Color.YELLOW);
        tip.setForeground(Color.RED);
        return tip;
      }
      public boolean contains(int x, int y) {
        if (x < 100) {
          setToolTipText("x < 100");
        } else {
          setToolTipText("else");
        }
        return super.contains(x, y);
      }
    };
    
    button.setToolTipText("Hello, World");
    frame.add(button, BorderLayout.NORTH);
    frame.setSize(300, 150);
    frame.setVisible(true);
  }
}