11.4 选择组件

1 复选框

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

/**
 * @version 1.34 2015-06-12
 * @author Cay Horstmann
 */
public class CheckBoxTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new CheckBoxFrame();
         frame.setTitle("CheckBoxTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

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

/**
 * A frame with a sample text label and check boxes for selecting font
 * attributes.
 */
public class CheckBoxFrame extends JFrame
{
   private JLabel label;
   private JCheckBox bold;
   private JCheckBox italic;
   private static final int FONTSIZE = 24;

   public CheckBoxFrame()
   {
      // add the sample text label

      label = new JLabel("The quick brown fox jumps over the lazy dog.");
      label.setFont(new Font("Serif", Font.BOLD, FONTSIZE));
      add(label, BorderLayout.CENTER);

      // this listener sets the font attribute of
      // the label to the check box state

      ActionListener listener = event -> {
         int mode = 0;
         if (bold.isSelected()) mode += Font.BOLD;
         if (italic.isSelected()) mode += Font.ITALIC;
         label.setFont(new Font("Serif", mode, FONTSIZE));
      };

      // add the check boxes

      JPanel buttonPanel = new JPanel();

      bold = new JCheckBox("Bold");
      bold.addActionListener(listener);
      bold.setSelected(true);
      buttonPanel.add(bold);

      italic = new JCheckBox("Italic");
      italic.addActionListener(listener);
      buttonPanel.add(italic);

      add(buttonPanel, BorderLayout.SOUTH);
      pack();
   }
}

---

2 单选按钮

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

/**
 * @version 1.34 2015-06-12
 * @author Cay Horstmann
 */
public class RadioButtonTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new RadioButtonFrame();
         frame.setTitle("RadioButtonTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

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

/**
 * A frame with a sample text label and radio buttons for selecting font sizes.
 */
public class RadioButtonFrame extends JFrame
{
   private JPanel buttonPanel;
   private ButtonGroup group;
   private JLabel label;
   private static final int DEFAULT_SIZE = 36;

   public RadioButtonFrame()
   {      
      // add the sample text label

      label = new JLabel("The quick brown fox jumps over the lazy dog.");
      label.setFont(new Font("Serif", Font.PLAIN, DEFAULT_SIZE));
      add(label, BorderLayout.CENTER);

      // add the radio buttons

      buttonPanel = new JPanel();
      group = new ButtonGroup();

      addRadioButton("Small", 8);
      addRadioButton("Medium", 12);
      addRadioButton("Large", 18);
      addRadioButton("Extra large", 36);

      add(buttonPanel, BorderLayout.SOUTH);
      pack();
   }

   /**
    * Adds a radio button that sets the font size of the sample text.
    * @param name the string to appear on the button
    * @param size the font size that this button sets
    */
   public void addRadioButton(String name, int size)
   {
      boolean selected = size == DEFAULT_SIZE;
      JRadioButton button = new JRadioButton(name, selected);
      group.add(button);
      buttonPanel.add(button);

      // this listener sets the label font size

      ActionListener listener = event -> label.setFont(new Font("Serif", Font.PLAIN, size));

      button.addActionListener(listener);
   }
}

---

3 边框

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

/**
 * @version 1.34 2015-06-13
 * @author Cay Horstmann
 */
public class BorderTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new BorderFrame();
         frame.setTitle("BorderTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;

/**
 * A frame with radio buttons to pick a border style.
 */
public class BorderFrame extends JFrame
{
   private JPanel demoPanel;
   private JPanel buttonPanel;
   private ButtonGroup group;

   public BorderFrame()
   {
      demoPanel = new JPanel();
      buttonPanel = new JPanel();
      group = new ButtonGroup();

      addRadioButton("Lowered bevel", BorderFactory.createLoweredBevelBorder());
      addRadioButton("Raised bevel", BorderFactory.createRaisedBevelBorder());
      addRadioButton("Etched", BorderFactory.createEtchedBorder());
      addRadioButton("Line", BorderFactory.createLineBorder(Color.BLUE));
      addRadioButton("Matte", BorderFactory.createMatteBorder(10, 10, 10, 10, Color.BLUE));
      addRadioButton("Empty", BorderFactory.createEmptyBorder());

      Border etched = BorderFactory.createEtchedBorder();
      Border titled = BorderFactory.createTitledBorder(etched, "Border types");
      buttonPanel.setBorder(titled);

      setLayout(new GridLayout(2, 1));
      add(buttonPanel);
      add(demoPanel);
      pack();
   }

   public void addRadioButton(String buttonName, Border b)
   {
      JRadioButton button = new JRadioButton(buttonName);
      button.addActionListener(event -> demoPanel.setBorder(b));
      group.add(button);
      buttonPanel.add(button);
   }
}

4 组合框

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

/**
 * @version 1.35 2015-06-12
 * @author Cay Horstmann
 */
public class ComboBoxTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new ComboBoxFrame();
         frame.setTitle("ComboBoxTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

import java.awt.BorderLayout;
import java.awt.Font;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

/**
 * A frame with a sample text label and a combo box for selecting font faces.
 */
public class ComboBoxFrame extends JFrame
{
   private JComboBox faceCombo;
   private JLabel label;
   private static final int DEFAULT_SIZE = 24;

   public ComboBoxFrame()
   {
      // add the sample text label

      label = new JLabel("The quick brown fox jumps over the lazy dog.");
      label.setFont(new Font("Serif", Font.PLAIN, DEFAULT_SIZE));
      add(label, BorderLayout.CENTER);

      // make a combo box and add face names

      faceCombo = new JComboBox<>();
      faceCombo.addItem("Serif");
      faceCombo.addItem("SansSerif");
      faceCombo.addItem("Monospaced");
      faceCombo.addItem("Dialog");
      faceCombo.addItem("DialogInput");

      // the combo box listener changes the label font to the selected face name

      faceCombo.addActionListener(event ->
         label.setFont(
            new Font(faceCombo.getItemAt(faceCombo.getSelectedIndex()), 
               Font.PLAIN, DEFAULT_SIZE)));

      // add combo box to a panel at the frame's southern border

      JPanel comboPanel = new JPanel();
      comboPanel.add(faceCombo);
      add(comboPanel, BorderLayout.SOUTH);
      pack();
   }
}

---

5 滑动条

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

/**
 * @version 1.15 2015-06-12
 * @author Cay Horstmann
 */
public class SliderTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         SliderFrame frame = new SliderFrame();
         frame.setTitle("SliderTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

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

/**
 * A frame with many sliders and a text field to show slider values.
 */
public class SliderFrame extends JFrame
{
   private JPanel sliderPanel;
   private JTextField textField;
   private ChangeListener listener;

   public SliderFrame()
   {
      sliderPanel = new JPanel();
      sliderPanel.setLayout(new GridBagLayout());

      // common listener for all sliders
      listener = event -> {
         // update text field when the slider value changes
         JSlider source = (JSlider) event.getSource();
         textField.setText("" + source.getValue());
      };

      // add a plain slider

      JSlider slider = new JSlider();
      addSlider(slider, "Plain");

      // add a slider with major and minor ticks

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);
      addSlider(slider, "Ticks");

      // add a slider that snaps to ticks

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setSnapToTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);
      addSlider(slider, "Snap to ticks");

      // add a slider with no track

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);
      slider.setPaintTrack(false);
      addSlider(slider, "No track");

      // add an inverted slider

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);
      slider.setInverted(true);
      addSlider(slider, "Inverted");

      // add a slider with numeric labels

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setPaintLabels(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);
      addSlider(slider, "Labels");

      // add a slider with alphabetic labels

      slider = new JSlider();
      slider.setPaintLabels(true);
      slider.setPaintTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);

      Dictionary labelTable = new Hashtable<>();
      labelTable.put(0, new JLabel("A"));
      labelTable.put(20, new JLabel("B"));
      labelTable.put(40, new JLabel("C"));
      labelTable.put(60, new JLabel("D"));
      labelTable.put(80, new JLabel("E"));
      labelTable.put(100, new JLabel("F"));

      slider.setLabelTable(labelTable);
      addSlider(slider, "Custom labels");

      // add a slider with icon labels

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setPaintLabels(true);
      slider.setSnapToTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(20);

      labelTable = new Hashtable();

      // add card images

      labelTable.put(0, new JLabel(new ImageIcon("nine.gif")));
      labelTable.put(20, new JLabel(new ImageIcon("ten.gif")));
      labelTable.put(40, new JLabel(new ImageIcon("jack.gif")));
      labelTable.put(60, new JLabel(new ImageIcon("queen.gif")));
      labelTable.put(80, new JLabel(new ImageIcon("king.gif")));
      labelTable.put(100, new JLabel(new ImageIcon("ace.gif")));

      slider.setLabelTable(labelTable);
      addSlider(slider, "Icon labels");

      // add the text field that displays the slider value

      textField = new JTextField();
      add(sliderPanel, BorderLayout.CENTER);
      add(textField, BorderLayout.SOUTH);
      pack();
   }

   /**
    * Adds a slider to the slider panel and hooks up the listener
    * @param s the slider
    * @param description the slider description
    */
   public void addSlider(JSlider s, String description)
   {
      s.addChangeListener(listener);
      JPanel panel = new JPanel();
      panel.add(s);
      panel.add(new JLabel(description));
      panel.setAlignmentX(Component.LEFT_ALIGNMENT);
      GridBagConstraints gbc = new GridBagConstraints();
      gbc.gridy = sliderPanel.getComponentCount();
      gbc.anchor = GridBagConstraints.WEST;
      sliderPanel.add(panel, gbc);
   }
}