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

public class FontsListJFrame extends JFrame implements ListSelectionListener
{
    private JList list;
    private JTextArea text;
    
    public FontsListJFrame()
    {
        super("系统字体预览");
        Dimension dim = getToolkit().getScreenSize();      //获得屏幕分辨率
        this.setBounds(dim.width/4,dim.height/4,dim.width/2,dim.height/2);//窗口居中
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);

        GraphicsEnvironment ge=GraphicsEnvironment.getLocalGraphicsEnvironment();
        String[] fontsName=ge.getAvailableFontFamilyNames(); //获得系统字体
        this.list = new JList(fontsName);      
        this.getContentPane().add(new JScrollPane(this.list));
        this.list.addListSelectionListener(this);          //注册选择事件监听器
        this.list.setCellRenderer(new CheckBoxListCellRenderer()); //设置自定义的单元渲染器
        
        this.text = new JTextArea("Welcome  欢迎");
        this.getContentPane().add(this.text,"South");
        this.setVisible(true);
    }

    class CheckBoxListCellRenderer extends JCheckBox implements ListCellRenderer  //列表框单元渲染器
    {                                                      //必须是内部类
        public Component getListCellRendererComponent(JList list,Object value,int index,boolean isSelected,boolean cellHasFocus)
        {
            setText(value.toString());
            setFont(new Font(value.toString(),Font.BOLD,16));       //以当前字符串作为字体名设置字体
            setBackground(isSelected ? Color.lightGray : Color.white); //选中数据项背景浅灰色
            setForeground(isSelected ? Color.red : Color.black);    //选中数据项红色显示
            setSelected(isSelected);                                //当前数据项选中状态
            return this;
        }
    }

    public void valueChanged(ListSelectionEvent e)         //在列表框中选择数据项时触发
    {                                        //一次选择，执行两次该事件？？为什么
        String selected = (String)list.getSelectedValue();
//        System.out.println(selected);
        this.text.setFont(new Font(selected,Font.BOLD,56));
    }
    
    public static void main(String[] args) 
    {
        new FontsListJFrame();
    }
}

        this.list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);   //设置为单选

  ////////////////////////////////

        if (e.getValueIsAdjusting()) {
            String selected = (String) list.getSelectedValue();
//            System.out.println(selected);
            this.text.setFont(new Font(selected, Font.BOLD, 56));
        }