mainframe.java

Java编程100例,提供了很多经典实例来说明Java

package jcomboboxdemo;

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

/**
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2002</p>
 * <p>Company: </p>
 * @author unascribed
 * @version 1.0
 */

public class MainFrame extends JFrame {
  private JPanel contentPane;
  private BorderLayout borderLayout1 = new BorderLayout();
  private JLabel jLabel1 = new JLabel();

  private String[] defaultSites={
        "http://www.pku.edu.cn",
        "http://www.edu.cn",
        "http://e.pku.edu.cn",
        "http://www.tsinghua.edu.cn",
        "http://www.google.com"
  };

  private String defaultEdit="http://www.pku.edu.cn";
  private JComboBox jComboBox1 = new JComboBox(defaultSites);

  //Construct the frame
  public MainFrame() {
    enableEvents(AWTEvent.WINDOW_EVENT_MASK);
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  //Component initialization
  private void jbInit() throws Exception  {
    //setIconImage(Toolkit.getDefaultToolkit().createImage(MainFrame.class.getResource("[Your Icon]")));
    contentPane = (JPanel) this.getContentPane();
    jLabel1.setFont(new java.awt.Font("Dialog", 0, 14));
    jLabel1.setHorizontalAlignment(SwingConstants.CENTER);
    jLabel1.setText("  地  址：");
    contentPane.setLayout(borderLayout1);
    this.setSize(new Dimension(468, 59));
    this.setTitle("JComboBoxDemo");
    jComboBox1.setFont(new java.awt.Font("Dialog", 0, 14));
    jComboBox1.setEditable(true);
    jComboBox1.setMaximumRowCount(5);
    jComboBox1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        jComboBox1_actionPerformed(e);
      }
    });
    jComboBox1.configureEditor(jComboBox1.getEditor(),defaultEdit);
    ComboBoxEditor comboxEditor=jComboBox1.getEditor();
    Component editorComp = comboxEditor.getEditorComponent();
    editorComp.setBackground(Color.white);
    editorComp.setForeground(Color.red);
    editorComp.setFont(new Font("Dialog",Font.PLAIN,14));
    contentPane.add(jLabel1, BorderLayout.WEST);
    contentPane.add(jComboBox1, BorderLayout.CENTER);
  }
  //Overridden so we can exit when window is closed
  protected void processWindowEvent(WindowEvent e) {
    super.processWindowEvent(e);
    if (e.getID() == WindowEvent.WINDOW_CLOSING) {
      System.exit(0);
    }
  }

  void jComboBox1_actionPerformed(ActionEvent e) {
    boolean isItemPresent = false;

    for(int i=0;i<jComboBox1.getItemCount();i++)
    {
        if(jComboBox1.getItemAt(i).equals(jComboBox1.getSelectedItem())){
                isItemPresent=false;
                break;
        }
    }

    if(!isItemPresent){
        jComboBox1.insertItemAt(jComboBox1.getSelectedItem(),0);
        isItemPresent=false;
    }



  }
}