comboboxes.java

Thinking in JAVA第四版源代码

//: gui/ComboBoxes.java
// Using drop-down lists.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import static net.mindview.util.SwingConsole.*;

public class ComboBoxes extends JFrame {
  private String[] description = {
    "Ebullient", "Obtuse", "Recalcitrant", "Brilliant",
    "Somnescent", "Timorous", "Florid", "Putrescent"
  };
  private JTextField t = new JTextField(15);
  private JComboBox c = new JComboBox();
  private JButton b = new JButton("Add items");
  private int count = 0;
  public ComboBoxes() {
    for(int i = 0; i < 4; i++)
      c.addItem(description[count++]);
    t.setEditable(false);
    b.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        if(count < description.length)
          c.addItem(description[count++]);
      }
    });
    c.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        t.setText("index: "+ c.getSelectedIndex() + "   " +
         ((JComboBox)e.getSource()).getSelectedItem());
      }
    });
    setLayout(new FlowLayout());
    add(t);
    add(c);
    add(b);
  }
  public static void main(String[] args) {
    run(new ComboBoxes(), 200, 175);
  }
} ///:~