java.lang.Object
 Ｌ java.awt.Component
     Ｌ java.awt.Container
         Ｌ javax.swing.JComponent
             Ｌ javax.swing.JComboBox

public class JComboBox extends JComponent implements ItemSelectable, ListDataListener, ActionListener, Accessible 

JComboBoxクラスのコンストラクタ

JComboBox
public JComboBox()

JComboBox combo = new JComboBox();

サンプルプログラム

/**
 * JComboBoxクラスの定義とコンストラクタ
 */
import javax.swing.*;
import java.awt.BorderLayout;

public class JComboBoxTest1 extends JFrame{

  public static void main(String[] args){
    JComboBoxTest1 frame = new JComboBoxTest1();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest1(){
    JComboBox combo = new JComboBox();

    JPanel p = new JPanel();
    p.add(combo);

    getContentPane().add(p, BorderLayout.CENTER);
  }
}

JComboBox
public JComboBox(Object[] items)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
JComboBox combo = new JComboBox(combodata);

サンプルプログラム

/**
 * コンボボックスの初期データを配列を使って設定する
 */
import javax.swing.*;
import java.awt.BorderLayout;

public class JComboBoxTest2 extends JFrame{

  public static void main(String[] args){
    JComboBoxTest2 frame = new JComboBoxTest2();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest2(){
    String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
    JComboBox combo = new JComboBox(combodata);

    JPanel p = new JPanel();
    p.add(combo);

    getContentPane().add(p, BorderLayout.CENTER);
  }
}

JComboBox
public JComboBox(Vector items)

Vector combodata = new Vector();
combodata.add("Swing");
combodata.add("Java2D");
combodata.add("Java3D");
combodata.add("JavaMail");
JComboBox combo = new JComboBox(combodata);

サンプルプログラム

/**
 * コンボボックスの初期データをVectorクラスを使って設定する
 */
import javax.swing.*;
import java.awt.BorderLayout;
import java.util.Vector;

public class JComboBoxTest3 extends JFrame{

  public static void main(String[] args){
    JComboBoxTest3 frame = new JComboBoxTest3();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest3(){
    Vector combodata = new Vector();
    combodata.add("Swing");
    combodata.add("Java2D");
    combodata.add("Java3D");
    combodata.add("JavaMail");

    JComboBox combo = new JComboBox(combodata);

    JPanel p = new JPanel();
    p.add(combo);

    getContentPane().add(p, BorderLayout.CENTER);
  }
}

setPreferredSize
public void setPreferredSize(Dimension preferredSize)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
JComboBox combo = new JComboBox(combodata);
combo.setPreferredSize(new Dimension(180, 60));

サンプルプログラム

/**
 * コンボボックスのサイズを設定する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;

public class JComboBoxTest4 extends JFrame{

  public static void main(String[] args){
    JComboBoxTest4 frame = new JComboBoxTest4();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest4(){
    String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
    JComboBox combo = new JComboBox(combodata);
    combo.setPreferredSize(new Dimension(180, 40));

    JPanel p = new JPanel();
    p.add(combo);

    getContentPane().add(p, BorderLayout.CENTER);
  }
}

setMaximumRowCount
public void setMaximumRowCount(int count)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
JComboBox combo = new JComboBox(combodata);
combo.setMaximumRowCount(5);

サンプルプログラム

/**
 * ドロップダウンリストで表示可能な最大項目数を設定する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;

public class JComboBoxTest5 extends JFrame{

  public static void main(String[] args){
    JComboBoxTest5 frame = new JComboBoxTest5();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest5(){
    String[] startTime = {"08:00","09:00","10:00","11:00",
                          "12:00","13:00","14:00","15:00",
                          "16:00","17:00","18:00","19:00"};

    String[] endTime = {"08:00","09:00","10:00","11:00",
                          "12:00","13:00","14:00","15:00",
                          "16:00","17:00","18:00","19:00"};

    JComboBox combo1 = new JComboBox(startTime);
    combo1.setPreferredSize(new Dimension(80, 30));

    JComboBox combo2 = new JComboBox(endTime);
    combo2.setPreferredSize(new Dimension(80, 30));
    combo2.setMaximumRowCount(5);

    JPanel p = new JPanel();
    p.add(new JLabel("start:"));
    p.add(combo1);
    p.add(new JLabel("  end:"));
    p.add(combo2);

    getContentPane().add(p, BorderLayout.CENTER);
  }
}

setSelectedIndex
public void setSelectedIndex(int anIndex)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
JComboBox combo = new JComboBox(combodata);
combo.setSelectedIndex(2);

setSelectedItem
public void setSelectedItem(Object anObject)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
JComboBox combo = new JComboBox(combodata);
combo.setSelectedItem("Java3D");

サンプルプログラム

/**
 * コンボボックスで指定の項目を選択する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;

public class JComboBoxTest6 extends JFrame{

  public static void main(String[] args){
    JComboBoxTest6 frame = new JComboBoxTest6();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest6(){
    String[] startTime = {"08:00","09:00","10:00","11:00",
                          "12:00","13:00","14:00","15:00",
                          "16:00","17:00","18:00","19:00"};

    String[] endTime = {"08:00","09:00","10:00","11:00",
                          "12:00","13:00","14:00","15:00",
                          "16:00","17:00","18:00","19:00"};

    JComboBox combo1 = new JComboBox(startTime);
    combo1.setPreferredSize(new Dimension(80, 30));
    combo1.setSelectedIndex(1);

    JComboBox combo2 = new JComboBox(endTime);
    combo2.setPreferredSize(new Dimension(80, 30));
    combo2.setSelectedItem("15:00");

    JPanel p = new JPanel();
    p.add(new JLabel("start:"));
    p.add(combo1);
    p.add(new JLabel("  end:"));
    p.add(combo2);

    getContentPane().add(p, BorderLayout.CENTER);
  }
}

getSelectedItem
public Object getSelectedItem()

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
JComboBox combo = new JComboBox(combodata);

String data = (String)combo.getSelectedItem();

選択されている項目のインデックスを取得する

getSelectedIndex
public int getSelectedIndex()

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
JComboBox combo = new JComboBox(combodata);

int index = combo.getSelectedIndex();

サンプルプログラム

/**
 * 選択されている項目を取得する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;
import java.awt.event.*;

public class JComboBoxTest7 extends JFrame implements ActionListener{

  JComboBox startCombo;
  JComboBox endCombo;
  JLabel label;

  public static void main(String[] args){
    JComboBoxTest7 frame = new JComboBoxTest7();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest7(){
    String[] startTime = {"08:00","09:00","10:00","11:00",
                          "12:00","13:00","14:00","15:00",
                          "16:00","17:00","18:00","19:00"};

    String[] endTime = {"08:00","09:00","10:00","11:00",
                          "12:00","13:00","14:00","15:00",
                          "16:00","17:00","18:00","19:00"};

    startCombo = new JComboBox(startTime);
    startCombo.setPreferredSize(new Dimension(80, 30));

    startCombo.addActionListener(this);

    endCombo = new JComboBox(endTime);
    endCombo.setPreferredSize(new Dimension(80, 30));

    endCombo.addActionListener(this);

    JPanel p = new JPanel();
    p.add(new JLabel("start:"));
    p.add(startCombo);
    p.add(new JLabel("  end:"));
    p.add(endCombo);

    label = new JLabel();
    JPanel labelPanel = new JPanel();
    labelPanel.add(label);

    getContentPane().add(p, BorderLayout.CENTER);
    getContentPane().add(labelPanel, BorderLayout.PAGE_END);
  }

  public void actionPerformed(ActionEvent e) {
    String start;
    String end;

    if (startCombo.getSelectedIndex() == -1){
        start = "(not select)";
    }else{
        start = (String)startCombo.getSelectedItem();
    }

    if (endCombo.getSelectedIndex() == -1){
        end = "(not select)";
    }else{
        end = (String)endCombo.getSelectedItem();
    }

    label.setText("START:" + start + ", END:" + end);
  }
}

setEnabled
public void setEnabled(boolean b)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
JComboBox combo = new JComboBox(combodata);

combo.setEnabled(false);

サンプルプログラム

/**
 * コンボボックスを無効にする
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;

public class JComboBoxTest8 extends JFrame{

  public static void main(String[] args){
    JComboBoxTest8 frame = new JComboBoxTest8();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest8(){
    String[] startTime = {"08:00","09:00","10:00","11:00",
                          "12:00","13:00","14:00","15:00",
                          "16:00","17:00","18:00","19:00"};

    String[] endTime = {"08:00","09:00","10:00","11:00",
                          "12:00","13:00","14:00","15:00",
                          "16:00","17:00","18:00","19:00"};

    JComboBox startCombo = new JComboBox(startTime);
    startCombo.setPreferredSize(new Dimension(80, 30));

    JComboBox endCombo = new JComboBox(endTime);
    endCombo.setPreferredSize(new Dimension(80, 30));
    endCombo.setEnabled(false);

    JPanel p = new JPanel();
    p.add(new JLabel("start:"));
    p.add(startCombo);
    p.add(new JLabel("  end:"));
    p.add(endCombo);

    getContentPane().add(p, BorderLayout.CENTER);
  }
}

java.lang.Object
 Ｌ javax.swing.AbstractListModel
     Ｌ javax.swing.DefaultComboBoxModel

public class DefaultComboBoxModel extends AbstractListModel implements MutableComboBoxModel, Serializable

DefaultComboBoxModelクラスのコンストラクタ

DefaultComboBoxModel
public DefaultComboBoxModel()

DefaultComboBoxModel model = new DefaultComboBoxModel();

JComboBox
public JComboBox(ComboBoxModel aModel)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);
JComboBox combo = new JComboBox(model);

メソッドを使って設定する

setModel
public void setModel(ComboBoxModel aModel)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

JComboBox combo = new JComboBox();
combo.setModel(combo);

サンプルプログラム

/**
 * データモデルからJComboBoxオブジェクトを作成する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;

public class JComboBoxTest9 extends JFrame{

  JComboBox startCombo;
  JComboBox endCombo;

  public static void main(String[] args){
    JComboBoxTest9 frame = new JComboBoxTest9();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest9(){
    String[] startTime = {"08:00","09:00","10:00","11:00",
                          "12:00","13:00","14:00","15:00",
                          "16:00","17:00","18:00","19:00"};

    String[] endTime = {"08:00","09:00","10:00","11:00",
                          "12:00","13:00","14:00","15:00",
                          "16:00","17:00","18:00","19:00"};

    DefaultComboBoxModel startModel = new DefaultComboBoxModel(startTime);
    JComboBox startCombo = new JComboBox(startModel);

    startCombo.setPreferredSize(new Dimension(80, 30));

    DefaultComboBoxModel endModel = new DefaultComboBoxModel(endTime);
    JComboBox endCombo = new JComboBox();
    endCombo.setModel(endModel);
    endCombo.setPreferredSize(new Dimension(80, 30));

    JPanel p = new JPanel();
    p.add(new JLabel("start:"));
    p.add(startCombo);
    p.add(new JLabel("  end:"));
    p.add(endCombo);

    getContentPane().add(p, BorderLayout.CENTER);
  }
}

DefaultComboBoxModel
public DefaultComboBoxModel(Object[] items)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

Vectorを使って初期データを設定する

DefaultComboBoxModel
public DefaultComboBoxModel(Vector v)

Vector combodata = new Vector();
combodata.add("Swing");
combodata.add("Java2D");
combodata.add("Java3D");
combodata.add("JavaMail");
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

サンプルプログラム

/**
 * データモデルの初期データを設定する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;
import java.util.Vector;

public class JComboBoxTest10 extends JFrame{

  JComboBox startCombo;
  JComboBox endCombo;

  public static void main(String[] args){
    JComboBoxTest10 frame = new JComboBoxTest10();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest10(){
    Vector combodata = new Vector();
    combodata.add("Swing");
    combodata.add("Java2D");
    combodata.add("Java3D");
    combodata.add("JavaMail");

    DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);
    JComboBox combo = new JComboBox(model);

    combo.setPreferredSize(new Dimension(80, 30));

    JPanel p = new JPanel();
    p.add(combo);

    getContentPane().add(p, BorderLayout.CENTER);
  }
}

addElement
public void addElement(Object anObject)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

model.addElement("Servlet");

サンプルプログラム

/**
 * データモデルにデータを追加する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;
import java.awt.event.*;

public class JComboBoxTest11 extends JFrame implements ActionListener{

  DefaultComboBoxModel model;
  JTextField text;
  JButton button;

  public static void main(String[] args){
    JComboBoxTest11 frame = new JComboBoxTest11();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest11(){
    String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
    model = new DefaultComboBoxModel(combodata);

    JComboBox combo = new JComboBox(model);
    combo.setPreferredSize(new Dimension(80, 30));

    JPanel p = new JPanel();
    p.add(combo);

    text = new JTextField(10);
    button = new JButton("add");
    button.addActionListener(this);

    JPanel controlPanel = new JPanel();
    controlPanel.add(text);
    controlPanel.add(button);

    getContentPane().add(p, BorderLayout.CENTER);
    getContentPane().add(controlPanel, BorderLayout.PAGE_END);
  }

  public void actionPerformed(ActionEvent e) {
    String newdata = text.getText();

    if ((newdata == null) || (newdata.equals(""))){
      return;
    }

    model.addElement(newdata);
    text.setText("");
  }
}

insertElementAt
public void insertElementAt(Object anObject,
                            int index)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

model.insertElementAt("Servlet", 2);

サンプルプログラム

/**
 * データモデルの指定の位置にデータを挿入する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;
import java.awt.event.*;

public class JComboBoxTest12 extends JFrame implements ActionListener{

  DefaultComboBoxModel model;
  JTextField datatext;
  JTextField indextext;
  JButton button;

  public static void main(String[] args){
    JComboBoxTest12 frame = new JComboBoxTest12();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest12(){
    String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
    model = new DefaultComboBoxModel(combodata);

    JComboBox combo = new JComboBox(model);
    combo.setPreferredSize(new Dimension(80, 30));

    JPanel p = new JPanel();
    p.add(combo);

    datatext = new JTextField(6);
    indextext = new JTextField(2);
    button = new JButton("insert");
    button.addActionListener(this);

    JPanel controlPanel = new JPanel();
    controlPanel.add(new JLabel("index:"));
    controlPanel.add(indextext);
    controlPanel.add(new JLabel("data:"));
    controlPanel.add(datatext);
    controlPanel.add(button);

    getContentPane().add(p, BorderLayout.CENTER);
    getContentPane().add(controlPanel, BorderLayout.PAGE_END);
  }

  public void actionPerformed(ActionEvent e) {
    int index = Integer.parseInt(indextext.getText());
    String newdata = datatext.getText();

    if ((newdata == null) || (newdata.equals(""))){
      return;
    }

    model.insertElementAt(newdata, index);
    indextext.setText("");
    datatext.setText("");
  }
}

removeElementAt
public void removeElementAt(int index)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

model.removeElementAt(1);

removeElement
public void removeElement(Object anObject)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

model.removeElement("Java2D");

サンプルプログラム

/**
 * データモデルからデータを削除する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;
import java.awt.event.*;

public class JComboBoxTest13 extends JFrame implements ActionListener{

  DefaultComboBoxModel model;
  JTextField indextext;
  JButton button;

  public static void main(String[] args){
    JComboBoxTest13 frame = new JComboBoxTest13();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest13(){
    String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
    model = new DefaultComboBoxModel(combodata);

    JComboBox combo = new JComboBox(model);
    combo.setPreferredSize(new Dimension(80, 30));

    JPanel p = new JPanel();
    p.add(combo);

    indextext = new JTextField(2);
    button = new JButton("delete");
    button.addActionListener(this);

    JPanel controlPanel = new JPanel();
    controlPanel.add(new JLabel("index:"));
    controlPanel.add(indextext);
    controlPanel.add(button);

    getContentPane().add(p, BorderLayout.CENTER);
    getContentPane().add(controlPanel, BorderLayout.PAGE_END);
  }

  public void actionPerformed(ActionEvent e) {
    int index = Integer.parseInt(indextext.getText());

    int size = model.getSize();
    if ((index < 0) || (index >= size)){
        indextext.setText("");
        return;
    }

    model.removeElementAt(index);
    indextext.setText("");
  }
}

setSelectedItem
public void setSelectedItem(Object anObject)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

model.setSelectedItem("Java2D");

getElementAt
public Object getElementAt(int index)

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

model.setSelectedItem(model.getElementAt(1));

サンプルプログラム

/**
 * データモデルで指定の項目を選択する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;

public class JComboBoxTest14 extends JFrame{

  public static void main(String[] args){
    JComboBoxTest14 frame = new JComboBoxTest14();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest14(){
    String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
    DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

    JComboBox combo = new JComboBox(model);
    combo.setPreferredSize(new Dimension(80, 30));

    model.setSelectedItem(model.getElementAt(1));

    JPanel p = new JPanel();
    p.add(combo);

    getContentPane().add(p, BorderLayout.CENTER);
  }
}

getSelectedItem
public Object getSelectedItem()

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

String data = (String)model.getSelectedItem();

サンプルプログラム

/**
 * データモデルで選択された項目を取得する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;
import java.awt.event.*;

public class JComboBoxTest15 extends JFrame implements ItemListener{

  DefaultComboBoxModel model;
  JLabel label;

  public static void main(String[] args){
    JComboBoxTest15 frame = new JComboBoxTest15();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest15(){
    String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
    model = new DefaultComboBoxModel(combodata);

    JComboBox combo = new JComboBox(model);
    combo.setPreferredSize(new Dimension(80, 30));
    combo.addItemListener(this);

    JPanel p = new JPanel();
    p.add(combo);

    label = new JLabel();

    JPanel labelPanel = new JPanel();
    labelPanel.add(label);

    getContentPane().add(p, BorderLayout.CENTER);
    getContentPane().add(labelPanel, BorderLayout.PAGE_END);
  }

  public void itemStateChanged(ItemEvent e) {
    if (e.getStateChange() == ItemEvent.SELECTED){
      String data = (String)model.getSelectedItem();
      label.setText(data);
    }
  }
}

getSize
public int getSize()

String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

int count = model.getSize();

サンプルプログラム

/**
 * データモデルに含まれるデータの個数を取得する
 */
import javax.swing.*;
import java.awt.Dimension;
import java.awt.BorderLayout;
import java.awt.event.*;

public class JComboBoxTest16 extends JFrame implements ActionListener{

  DefaultComboBoxModel model;
  JButton button;

  public static void main(String[] args){
    JComboBoxTest16 frame = new JComboBoxTest16();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest16(){
    String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
    model = new DefaultComboBoxModel(combodata);

    JComboBox combo = new JComboBox(model);
    combo.setPreferredSize(new Dimension(80, 30));

    JPanel p = new JPanel();
    p.add(combo);

    button = new JButton("get all data");
    button.addActionListener(this);

    JPanel controlPanel = new JPanel();
    controlPanel.add(button);

    getContentPane().add(p, BorderLayout.CENTER);
    getContentPane().add(controlPanel, BorderLayout.PAGE_END);
  }

  public void actionPerformed(ActionEvent e) {
    int count = model.getSize();

    System.out.println("データ総数は:" + count + "です");

    for (int i = 0 ; i < count ; i++){
      String data = (String)model.getElementAt(i);
      System.out.println(data);
    }
  }
}

[xxxxxxxx@dddddddddddd JComboBox]$ データ総数は:4です
Swing
Java2D
Java3D
JavaMail

class MyCellRenderer extends JLabel implements ListCellRenderer {
 public Component getListCellRendererComponent(
           JList list,
           Object value,
           int index,
           boolean isSelected,
           boolean cellHasFocus){
 
    /* 必要な処理を記述する */

  }
}

setRenderer
public void setRenderer(ListCellRenderer aRenderer)

JComboBox combo = new JComboBox();

MyCellRenderer renderer = new MyCellRenderer();
combo.setRenderer(renderer);

getListCellRendererComponent
Component getListCellRendererComponent(JList list,
                                       Object value,
                                       int index,
                                       boolean isSelected,
                                       boolean cellHasFocus)

class MyCellRenderer extends JLabel implements ListCellRenderer {
  public Component getListCellRendererComponent(
            JList list,
            Object value,
            int index,
            boolean isSelected,
            boolean cellHasFocus){

    return this;
  }
}

呼び出し元のオブジェクトの判別

class MyCellRenderer extends JLabel implements ListCellRenderer {
  public Component getListCellRendererComponent(
            JList list,
            Object value,
            int index,
            boolean isSelected,
            boolean cellHasFocus){

    setText(value.toString());

    return this;
  }
}

class MyCellRenderer extends JLabel implements ListCellRenderer {
  public Component getListCellRendererComponent(
            JList list,
            Object value,
            int index,
            boolean isSelected,
           boolean cellHasFocus){

     String data = value.toString();
     setText(data.toUpperCase());

     return this;
  }
}

選択項目かどうかの判別

class MyCellRenderer extends JLabel implements ListCellRenderer {
  public Component getListCellRendererComponent(
            JList list,
            Object value,
            int index,
            boolean isSelected,
            boolean cellHasFocus){

     String data = value.toString();
     setText(data.toUpperCase());

     setOpaque(true);

     if (isSelected){
       setForeground(Color.white);
       setBackground(Color.black);
     }else{
       setForeground(Color.black);
       setBackground(Color.white);
     }

     return this;
  }
}

class MyCellRenderer extends JLabel implements ListCellRenderer {
  MyCellRenderer(){
    setOpaque(true);
  }

  public Component getListCellRendererComponent(
            JList list,
            Object value,
            int index,
            boolean isSelected,
            boolean cellHasFocus){

     String data = value.toString();
     setText(data.toUpperCase());

     if (isSelected){
       setForeground(Color.white);
       setBackground(Color.black);
     }else{
       setForeground(Color.black);
       setBackground(Color.white);
     }

     return this;
   }
}

サンプルプログラム

/**
 * getListCellRendererComponentメソッド
 */
import javax.swing.*;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.BorderLayout;
import java.awt.Component;

public class JComboBoxTest17 extends JFrame{

  public static void main(String[] args){
    JComboBoxTest17 frame = new JComboBoxTest17();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest17(){
    String[] combodata = {"Swing", "Java2D", "Java3D", "JavaMail"};
    DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

    JComboBox combo = new JComboBox(model);
    combo.setPreferredSize(new Dimension(140, 30));

    MyCellRenderer renderer = new MyCellRenderer();
    combo.setRenderer(renderer);

    JPanel p = new JPanel();
    p.add(combo);

    getContentPane().add(p, BorderLayout.CENTER);
  }

  class MyCellRenderer extends JLabel implements ListCellRenderer{
    MyCellRenderer(){
      setOpaque(true);
    }

    public Component getListCellRendererComponent(
            JList list,
            Object value,
            int index,
            boolean isSelected,
            boolean cellHasFocus){

      String data = value.toString();
      setText(data.toUpperCase());

      if (isSelected){
        setForeground(Color.white);
        setBackground(Color.black);
      }else{
        setForeground(Color.black);
        setBackground(Color.white);
      }

      return this;
    }
  }
}

class ComboLabel{
  String text;
  Icon icon;

  ComboLabel(String text, Icon icon){
    this.text = text;
    this.icon = icon;
  }

  public String getText(){
    return text;
  }

  public Icon getIcon(){
    return icon;
  }
}

DefaultComboBoxModel model = new DefaultComboBoxModel();
model.addElement(new ComboLabel("Text1", new ImageIcon("gazou1.png")));
model.addElement(new ComboLabel("Text2", new ImageIcon("gazou2.png")));
model.addElement(new ComboLabel("Text3", new ImageIcon("gazou3.png")));
model.addElement(new ComboLabel("Text4", new ImageIcon("gazou4.png")));

JComboBox combo = new JComboBox(model);

class MyCellRenderer extends JLabel implements ListCellRenderer {
  public Component getListCellRendererComponent(
            JList list,
            Object value,
            int index,
            boolean isSelected,
            boolean cellHasFocus){

     ComboLabel data = (ComboLabel)value;
     setText(data.getText());
     setIcon(data.getIcon());

     return this;
  }
}

サンプルプログラム

/**
 * コンボボックスに画像を表示する
 */
import javax.swing.*;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.BorderLayout;
import java.awt.Component;

public class JComboBoxTest18 extends JFrame{

  public static void main(String[] args){
    JComboBoxTest18 frame = new JComboBoxTest18();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest18(){
    DefaultComboBoxModel model = new DefaultComboBoxModel();
    model.addElement(new ComboLabel("Lion", new ImageIcon("./img/chapp_2.gif")));
    model.addElement(new ComboLabel("Elephant", new ImageIcon("./img/uma_b3.gif")));
    model.addElement(new ComboLabel("Ostrich", new ImageIcon("./img/tohoho.gif")));
    model.addElement(new ComboLabel("Hippo", new ImageIcon("./img/uma2.gif")));

    JComboBox combo = new JComboBox(model);

    MyCellRenderer renderer = new MyCellRenderer();
    combo.setRenderer(renderer);

    JPanel p = new JPanel();
    p.add(combo);

    getContentPane().add(p, BorderLayout.CENTER);
  }

  class ComboLabel{
    String text;
    Icon icon;

    ComboLabel(String text, Icon icon){
      this.text = text;
      this.icon = icon;
    }

    public String getText(){
      return text;
    }

    public Icon getIcon(){
      return icon;
    }
  }

  class MyCellRenderer extends JLabel implements ListCellRenderer{

    MyCellRenderer(){
      setOpaque(true);
    }

    public Component getListCellRendererComponent(
            JList list,
            Object value,
            int index,
            boolean isSelected,
            boolean cellHasFocus){

      ComboLabel data = (ComboLabel)value;
      setText(data.getText());
      setIcon(data.getIcon());

      if (isSelected){
        setForeground(Color.white);
        setBackground(Color.black);
      }else{
        setForeground(Color.black);
        setBackground(Color.white);
      }

      return this;
    }
  }
}

class MyCellRenderer extends JLabel implements ListCellRenderer {
  public Component getListCellRendererComponent(
            JList list,
            Object value,
            int index,
            boolean isSelected,
            boolean cellHasFocus){

      String data = value.toString();
      setText(data);

      if (isSelected){
        setForeground(Color.white);
        setBackground(Color.black);
      }else{
        setForeground(Color.black);

      if (index % 2 == 0){
        setBackground(Color.white);
      }else{
        setBackground(new Color(238, 232, 170));
      }
    }

    return this;
  }
}

サンプルプログラム

/**
 * 1行毎に背景色を変更する
 */
import javax.swing.*;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.BorderLayout;
import java.awt.Component;

public class JComboBoxTest19 extends JFrame{

  public static void main(String[] args){
    JComboBoxTest19 frame = new JComboBoxTest19();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  JComboBoxTest19(){
    String[] combodata = {"08:00","09:00","10:00","11:00",
                          "12:00","13:00","14:00","15:00",
                          "16:00","17:00","18:00","19:00"};

    DefaultComboBoxModel model = new DefaultComboBoxModel(combodata);

    JComboBox combo = new JComboBox(model);
    combo.setPreferredSize(new Dimension(140, 30));

    MyCellRenderer renderer = new MyCellRenderer();
    combo.setRenderer(renderer);

    JPanel p = new JPanel();
    p.add(combo);

    getContentPane().add(p, BorderLayout.CENTER);
  }

  class MyCellRenderer extends JLabel implements ListCellRenderer{

    MyCellRenderer(){
      setOpaque(true);
    }

    public Component getListCellRendererComponent(
            JList list,
            Object value,
            int index,
            boolean isSelected,
            boolean cellHasFocus){

      String data = value.toString();
      setText(data);

      if (isSelected){
        setForeground(Color.white);
        setBackground(Color.black);
      }else{
        setForeground(Color.black);

        if (index % 2 == 0){
          setBackground(Color.white);
        }else{
          setBackground(new Color(238, 232, 170));
        }
      }

      return this;
    }
  }
}