Jlist的使用

               以前对JList不大了解，只知道显示固定的数据，今天特地的看了一下JList的API，基本弄懂了JList的用法，可以实现JList的动态更新和图片加载。

      这是主类

package jlist_v1;

import java.awt.BorderLayout;

public class MyJistText extends JFrame {

	private JPanel contentPane;
	private JLabel label;
	private JList list;
    private Vector<Object>  dataVec;
    private JList< Object> list2;
    private int count=1;
    private JComboBox comboBox;
	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					MyJistText frame = new MyJistText();
					frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the frame.
	 */
	public MyJistText() {
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 450, 300);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		contentPane.setLayout(new BorderLayout(0, 0));
		setContentPane(contentPane);
		
		JScrollPane scrollPane = new JScrollPane();
		contentPane.add(scrollPane, BorderLayout.WEST);
		String[] words= { "quick", "brown", "hungry", "wild"};
		list = new JList(words);
		list.addMouseListener(new MouseAdapter() {
			@Override
			public void mouseClicked(MouseEvent e) {
				
				if(e.getClickCount()==2){
					//得到双击的item的index
					 int index = list.locationToIndex(e.getPoint());
		             System.out.println("Double clicked on Item " + index);
		             	//实现list2的动态更新
					dataVec.addElement(""+count++);
					list2.setModel(new StringListModel(dataVec));
					
				}
			}
		});
		scrollPane.setViewportView(list);
		//list.setLayoutOrientation(JList.HORIZONTAL_WRAP);
	//	list.setVisibleRowCount(2);//设置可见的行数
	//	list.setCellRenderer(new FontCellRenderer());
		list.setCellRenderer(new MyCellRenderer());
		list.addListSelectionListener(new ListSelectionListener() {
			@Override
			public void valueChanged(ListSelectionEvent e) {
				boolean flag=e.getValueIsAdjusting();
				int last=e.getLastIndex();
				if(flag){System.out.println("按下"+last);}
				else{
					 System.out.println("松开"+last);
				     System.out.println(list.getSelectedValue());
				     label.setText(list.getSelectedValue().toString());
				}
			
			
			}
		});
		dataVec=new Vector<Object>();
		dataVec.add("100");
		list2=new JList<Object>();
		list2.setModel(new StringListModel(dataVec));
		JScrollPane scrollPane_1 = new JScrollPane(list2);
		contentPane.add(scrollPane_1, BorderLayout.EAST);
		
		label = new JLabel("");
		contentPane.add(label, BorderLayout.SOUTH);
		
		comboBox = new JComboBox(words);
		comboBox.addItemListener(new ItemListener() {
			
			@Override
			public void itemStateChanged(ItemEvent e) {
				System.out.println(comboBox.getItemAt(comboBox.getSelectedIndex()));
			}
		});
		
		contentPane.add(comboBox, BorderLayout.NORTH);
		
		
	}

}

 要实现JList的动态更新，需要实现ListModel接口

class StringListModel implements ListModel
{
	
	private Vector<Object> dataVec;
	

	public StringListModel(Vector<Object> dataVec) {
		super();
		this.dataVec = dataVec;
	}

	@Override
	public int getSize() {
		return dataVec.size();
	}

	@Override
	public Object getElementAt(int index) {
		return dataVec.elementAt(index);
	}

	@Override
	public void addListDataListener(ListDataListener l) {
	}

	@Override
	public void removeListDataListener(ListDataListener l) {
	}
  
 
}

 

要实现JList元素的特殊效果，如加载图片，背景颜色设置，需要实现ListCellRenderer接口

class MyCellRenderer extends JLabel implements ListCellRenderer {
     final static ImageIcon longIcon = new ImageIcon("images/qq.png");
     final static ImageIcon shortIcon = new ImageIcon("images/weixin.png");
     
     public Component getListCellRendererComponent(
       JList list,              // the list
       Object value,            // value to display
       int index,               // cell index
       boolean isSelected,      // is the cell selected
       boolean cellHasFocus)    // does the cell have focus
     {
         String s = value.toString();
         setText(s);
         setIcon((s.length()>5) ? longIcon : shortIcon);
         if (isSelected) {
             setBackground(Color.CYAN);
             setForeground(list.getSelectionForeground());
         } else {
             setBackground(list.getBackground());
             setForeground(list.getForeground());
         }
         setEnabled(list.isEnabled());
         setFont(list.getFont());
         setOpaque(true);
         return this;
     }
 }

          这些在api中都有相应的范例，不做过多介绍，只不过，通过对JTABLE,JLIST和JCOMBOBOX的研究发现，其动态更新都需要实现相应的model，更改外观都需要实现相应的渲染器，这些组件都采用了MVC架构，知道这一点，对于其他组件的学习就容易多了。