如何在JList中突出显示一个项目?[副本]

基于SUN的ListDemo示例。

如果您在textfield中输入一些不在列表中的文本,并点击highlight,则会添加该文本。

如果文本在列表中,并且您点击了highlight,则列表中的条目将临时高亮显示为蓝色。

注意,这里的解决方案和匹配字段仅用于演示。为了更正确地实施,请考虑提出的其他想法并考虑使用 javax.swing.Timer

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

public class ListDemo extends JPanel {
    private JList list;
    private DefaultListModel listModel;
    public String match = null;

    private static final String hireString = "Highlight";
    private JTextField employeeName;

    public ListDemo() {
        super(new BorderLayout());

        listModel = new DefaultListModel();
        listModel.addElement("Test1");
        listModel.addElement("Test2");
        listModel.addElement("Test3");

        list = new JList(listModel);
        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        list.setSelectedIndex(0);
        list.setVisibleRowCount(5);
        list.setCellRenderer(new MyListCellRenderer());
        JScrollPane listScrollPane = new JScrollPane(list);

        JButton hireButton = new JButton(hireString);
        HireListener hireListener = new HireListener(hireButton);
        hireButton.setActionCommand(hireString);
        hireButton.addActionListener(hireListener);
        hireButton.setEnabled(false);

        employeeName = new JTextField(10);
        employeeName.addActionListener(hireListener);
        employeeName.getDocument().addDocumentListener(hireListener);
        listModel.getElementAt(list.getSelectedIndex()).toString();

        JPanel buttonPane = new JPanel();
        buttonPane.setLayout(new BoxLayout(buttonPane,
                                           BoxLayout.LINE_AXIS));
        buttonPane.add(Box.createHorizontalStrut(5));
        buttonPane.add(employeeName);
        buttonPane.add(hireButton);
        buttonPane.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));

        add(listScrollPane, BorderLayout.CENTER);
        add(buttonPane, BorderLayout.PAGE_END);
    }
    class MyListCellRenderer extends JLabel implements ListCellRenderer {
        public MyListCellRenderer() {
            setOpaque(true);
        }
        public Component getListCellRendererComponent(JList paramlist, Object value, int index, boolean isSelected, boolean cellHasFocus) {
            setText(value.toString());
            if (value.toString().equals(match)) {
                setBackground(Color.BLUE);
                SwingWorker worker = new SwingWorker() {
                    @Override
                    public Object doInBackground() {
                        try {
                            Thread.sleep(5000);
                        } catch (InterruptedException e) { /*Who cares*/ }
                        return null;
                    }
                    @Override
                    public void done() {
                        match = null;
                        list.repaint();
                    }
                };
                worker.execute();
            } else
                setBackground(Color.RED);
            return this;
        }
    }
    class HireListener implements ActionListener, DocumentListener {
        private boolean alreadyEnabled = false;
        private JButton button;
        public HireListener(JButton button) {
            this.button = button;
        }
        public void actionPerformed(ActionEvent e) {
            String name = employeeName.getText();
            if (listModel.contains(name)) {
                match = name;
                list.repaint();
                employeeName.requestFocusInWindow();
                employeeName.selectAll();
                return;
            }
            if (name.equals("")) {
                Toolkit.getDefaultToolkit().beep();
                employeeName.requestFocusInWindow();
                employeeName.selectAll();
                return;
            }
            int index = list.getSelectedIndex();
            if (index == -1)
                index = 0;
            else
                index++;
            listModel.insertElementAt(employeeName.getText(), index);
            employeeName.requestFocusInWindow();
            employeeName.setText("");
            list.setSelectedIndex(index);
            list.ensureIndexIsVisible(index);
        }
        public void insertUpdate(DocumentEvent e) {
            enableButton();
        }
        public void removeUpdate(DocumentEvent e) {
            handleEmptyTextField(e);
        }
        public void changedUpdate(DocumentEvent e) {
            if (!handleEmptyTextField(e))
                enableButton();
        }
        private void enableButton() {
            if (!alreadyEnabled)
                button.setEnabled(true);
        }
        private boolean handleEmptyTextField(DocumentEvent e) {
            if (e.getDocument().getLength() <= 0) {
                button.setEnabled(false);
                alreadyEnabled = false;
                return true;
            }
            return false;
        }
    }
    private static void createAndShowGUI() {
        JFrame frame = new JFrame("ListDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JComponent newContentPane = new ListDemo();
        newContentPane.setOpaque(true);
        frame.setContentPane(newContentPane);
        frame.pack();
        frame.setVisible(true);
    }
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() { createAndShowGUI(); }
        });
    }
}

简单地说,使用以下方法将自定义ListCellRenderer设置为JList:

list.setCellRenderer(myListCellrenderer);

public Component getListCellRendererComponent(.....) {
    Component c = super.getListCellRendererComponent();
    c.setBackGround(Color.blue)
    return c;
}

上面的示例假设您的自定义呈现器覆盖DefaultListCellRenderer

实现方法的自定义ListCellRenderer getListCellRendererComponent ,将可以访问 JList 以及它重新定义的价值。这为您提供了几个选项来确定何时绘制 n

1. 你可以把 让渲染器询问背景使用哪种颜色。这个 列表框 第一排是绿色,然后开始荡秋千 Timer 触发重绘,使背景恢复正常
2. 当业务逻辑决定何时应该将行显示为绿色时,您还可以选择在行的backing对象上设置状态,并在中测试该状态 ,如果状态正确,则将bg设置为绿色。同样,您可以选择设置摆动 还原备份对象的状态。