Java Swing组件下拉菜单控件JComboBox用法示例-编程学习网

本文实例讲述了Java Swing组件下拉菜单控件JComboBox用法。分享给大家供大家参考，具体如下：

JComboBox是Swing中的下拉菜单控件。它永远只能选中一个项目，然而比单选按钮节省空间。如果使用setEditable设置为true则内部选项的文本可以编辑，因此这种组件被称为组合框。注意，对选项的编辑只会影响当前项，而不会改变列表内容。可以使用addItem方法来添加选项列表，或者使用insertItemAt在任何位置插入选项；然而如果有大量选项需要添加，这种方法是非常笨重的，可以先构造一个DefaultComboBoxModel，使用addElement加载选项，最后在调用JComboBox的setModel方法。

常用方法如下：

Java Swing组件下拉菜单控件JComboBox用法示例

示例代码：

JComboBoxBasicUseDemo.java

package awtDemo;import java.awt.BorderLayout;import java.awt.Font;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.ItemEvent;import java.awt.event.ItemListener;import javax.swing.JComboBox;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.event.PopupMenuEvent;import javax.swing.event.PopupMenuListener;public class JComboBoxBasicUseDemo extends JFrame{  private static final long serialVersionUID = -8161981948004677531L;  int DEFAULT_WIDTH = 600;  int DEFAULT_HEIGHT = 400;  private JLabel label;  private JComboBox<String> faceCombo;  private static final int FONTSIZE = 12;    @SuppressWarnings("unused")    public JComboBoxBasicUseDemo(){    setTitle("JComboBoxDemo - www.jb51.net");    setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);    //添加label    label = new JLabel("欢迎来到编程网 www.jb51.net");    label.setFont(new Font("Serif",Font.PLAIN, FONTSIZE));    add(label, BorderLayout.CENTER);    //actionListener    ActionListener actionListener = new ActionListener(){      public void actionPerformed(ActionEvent e) {        if(e.getSource() instanceof JComboBox){          @SuppressWarnings({ "unchecked", "rawtypes" })          JComboBox<String> comboBox = (JComboBox)e.getSource();          String fontName = comboBox.getSelectedItem().toString();          label.setFont(new Font(fontName, Font.PLAIN, FONTSIZE));          System.out.printf("%s%n", "actionPerformed called");        }      }    };    //popupMenuListener    PopupMenuListener popupMenuListener = new PopupMenuListener() {      @Override      public void popupMenuCanceled(PopupMenuEvent e) {        System.out.println("下拉菜单取消");      }      @SuppressWarnings("unchecked")            @Override      public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {        System.out.println("下拉菜单合上");        JComboBox<String> source = (JComboBox<String>)e.getSource();      }      @Override      public void popupMenuWillBecomeVisible(PopupMenuEvent e) {        System.out.println("下拉菜单弹出");      }    };    //itemListener    ItemListener itemListener = new ItemListener() {      @Override      public void itemStateChanged(ItemEvent arg0) {        // TODO Auto-generated method stub        if(ItemEvent.SELECTED == arg0.getStateChange()){          String selectedItem = arg0.getItem().toString();          label.setFont(new Font(selectedItem, Font.PLAIN, FONTSIZE));          System.out.printf("new selected item : %s%n",selectedItem);        }        if(ItemEvent.DESELECTED == arg0.getStateChange()){          String selectedItem = arg0.getItem().toString();          System.out.printf("deselected item : %s%n",selectedItem);        }      }      };    //添加一个JComboBox    faceCombo = new JComboBox<String>();    faceCombo.setEditable(true);    //faceCombo.addActionListener(actionListener);    //faceCombo.addPopupMenuListener(popupMenuListener);    faceCombo.addItemListener(itemListener);    faceCombo.setEnabled(true);    faceCombo.addItem("Serif");    faceCombo.addItem("SansSerif");    faceCombo.addItem("Monospaced");    faceCombo.addItem("Dialog");    faceCombo.addItem("DialogInput");    add(faceCombo, BorderLayout.SOUTH);  }  public static void main(String[] args) {    // TODO Auto-generated method stub    //创建窗体并指定标题    JComboBoxBasicUseDemo frame = new JComboBoxBasicUseDemo();    //关闭窗体后退出程序    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);    //自动适配所有控件大小    //frame.pack();    //设置窗体位置在屏幕中央    frame.setLocationRelativeTo(null);    //显示窗体    frame.setVisible(true);  }}

阅读原文内容投诉

免责声明：

① 本站未注明“稿件来源”的信息均来自网络整理。其文字、图片和音视频稿件的所属权归原作者所有。本站收集整理出于非商业性的教育和科研之目的，并不意味着本站赞同其观点或证实其内容的真实性。仅作为临时的测试数据，供内部测试之用。本站并未授权任何人以任何方式主动获取本站任何信息。

② 本站未注明“稿件来源”的临时测试数据将在测试完成后最终做删除处理。有问题或投稿请发送至: 邮箱/279061341@qq.com QQ/279061341