choicepanel.java

Java实例入门

package beantest;

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

/**
 * Title:        制作一个JavaBean
 * Description:  这个工程中我们制作了一个用于日期显示的JavaBean
 * Copyright:    Copyright (c) 2001
 * Company:
 * @author
 * @version 1.0
 */
public class ChoicePanel extends JPanel {
  private ButtonGroup bg = new ButtonGroup();
  private GridLayout gl = new GridLayout(5,1,5,5);
  private JRadioButton item1 = new JRadioButton("Month Day Year");
  private JRadioButton item2 = new JRadioButton("Month Day Year Era");
  private JRadioButton item3 = new JRadioButton("Year Month Day");
  private JRadioButton item4 = new JRadioButton("Month Year");
  private JRadioButton item5 = new JRadioButton("Day Month Year");
  private transient Vector actionListeners;

  public ChoicePanel() {
    try  {
      jbInit();
    }
    catch (Exception ex) {
      ex.printStackTrace();
    }
  }

  void jbInit() throws Exception {
    this.setLayout(gl);

    bg.add(item1);    bg.add(item2);
    bg.add(item3);    bg.add(item4);
    bg.add(item5);

    this.add(item1, null);    this.add(item2, null);
    this.add(item3, null);    this.add(item4, null);
    this.add(item5, null);

    item1.addItemListener(new java.awt.event.ItemListener() {
      public void itemStateChanged(ItemEvent e) {
        choiceChanged(e);
      }
    });

    item2.addItemListener(new java.awt.event.ItemListener() {
      public void itemStateChanged(ItemEvent e) {
        choiceChanged(e);
      }
    });

    item3.addItemListener(new java.awt.event.ItemListener() {
      public void itemStateChanged(ItemEvent e) {
        choiceChanged(e);
      }
    });

    item4.addItemListener(new java.awt.event.ItemListener() {
      public void itemStateChanged(ItemEvent e) {
        choiceChanged(e);
      }
    });

    item5.addItemListener(new java.awt.event.ItemListener() {
      public void itemStateChanged(ItemEvent e) {
        choiceChanged(e);
      }
    });


  }

  //
  // allow for the setting of a given radio button by int value
  //
  // method is called in a "one" based mechanism (i.e., if you want to select
  // the first radio button you call setSelectedItem(1);
  //
  public void setSelectedItem(int which){
    Enumeration e = bg.getElements();
    JRadioButton jr = null;
    int i = 0;

    try{
      for( ; i <= which; i++)
        jr = (JRadioButton)e.nextElement();
    }
    catch(NoSuchElementException x){
      x.printStackTrace();
    }
    jr.setSelected(true);
  }

  //
  // allows you to ask the component "which item is selected right now" and get
  // back a 1 based response (i.e., if the third radio button is selected this
  // method returns 3
  //
  public int getSelectedItem(){
    Enumeration e = bg.getElements();
    int which = 0;
    JRadioButton jr = null;

    try{
      while(e.hasMoreElements()){
        which +=1;
        jr = (JRadioButton)e.nextElement();
        if( jr.isSelected() )
          break;
      }
    }
    catch(NoSuchElementException x){
      x.printStackTrace();
      return 0;
    }

    return which-1;
  }

  //
  // when selection changes, find out which control is now selected and fire
  // the appropriate event
  //
  // this method is listened to in the 'live' version of the Customizer
  void choiceChanged(ItemEvent e){

    if(e.getStateChange() == ItemEvent.SELECTED){
      System.out.println("Selected Logic entered");
      if(item1.isSelected())
        fireActionPerformed(new ActionEvent(this, 1, "item1Selected"));

      else if(item2.isSelected())
        fireActionPerformed(new ActionEvent(this, 2, "item2Selected"));

      else if(item3.isSelected())
        fireActionPerformed(new ActionEvent(this, 3, "item3Selected"));

      else if(item4.isSelected())
        fireActionPerformed(new ActionEvent(this, 4, "item4Selected"));

      else if(item5.isSelected())
        fireActionPerformed(new ActionEvent(this, 5, "item5Selected"));
    }
  }

  public synchronized void removeActionListener(ActionListener l) {
    if (actionListeners != null && actionListeners.contains(l)) {
      Vector v = (Vector) actionListeners.clone();
      v.removeElement(l);
      actionListeners = v;
    }
  }

  public synchronized void addActionListener(ActionListener l) {
    Vector v = actionListeners == null ? new Vector(2) : (Vector) actionListeners.clone();
    if (!v.contains(l)) {
      v.addElement(l);
      actionListeners = v;
    }
  }

  protected void fireActionPerformed(ActionEvent e) {
    if (actionListeners != null) {
      Vector listeners = actionListeners;
      int count = listeners.size();
      for (int i = 0; i < count; i++)
        ((ActionListener) listeners.elementAt(i)).actionPerformed(e);
    }
  }

}