在滚动窗格中获取滚动条以"always on"

Question

我有两个滚动窗格，我正试图将滚动条设置为始终可见。由于某种原因，当我尝试使用下面的代码(滚动代码(时，我得到了一个错误，即"方法setHorizontalScrollBarPolicy(int(对于类型JTextPane是未定义的"。有什么建议吗？

滚动代码：

scrollPane.setHorizontalScrollBarPolicy(
   JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
scrollPane.setVerticalScrollBarPolicy(
   JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

我创建滚动窗格的代码：

JPanel ScrollPanes = new JPanel();
frame.getContentPane().add(ScrollPanes, BorderLayout.CENTER);
ScrollPanes.setLayout(new GridLayout(0, 2, 0, 0));
JTextPane textPane_0 = new JTextPane();
ScrollPanes.add(textPane_0);
textPane_0.setHorizontalScrollBarPolicy(
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
textPane_0.setVerticalScrollBarPolicy(
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
JTextPane textPane_1 = new JTextPane();
ScrollPanes.add(textPane_1);

完整代码：

package swing;
import java.awt.EventQueue;
public class Swing {
    private JFrame frame;
    private JTextField textField;
    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Swing window = new Swing();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }
    /**
     * Create the application.
     */
    public Swing() {
        initialize();
    }
    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frame = new JFrame();
        frame.setBounds(100, 100, 600, 500);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel TopApps = new JPanel();
        frame.getContentPane().add(TopApps, BorderLayout.NORTH);
        TopApps.setLayout(new FlowLayout(FlowLayout.LEFT, 5, 5));

        JComboBox comboBox = new JComboBox();
        comboBox.setPreferredSize(new Dimension(100, 20));
        TopApps.add(comboBox);
        textField = new JTextField();
        TopApps.add(textField);
        textField.setColumns(20);
        JScrollPane scrollPanes = new JScrollPane();
        frame.getContentPane().add(scrollPanes, BorderLayout.CENTER);
        scrollPanes.setLayout(new GridLayout(0, 2, 0, 0));
        JTextPane textPane_0 = new JTextPane();
        scrollPanes.add(textPane_0);
        textPane_0.setBorder(BorderFactory.createLoweredBevelBorder());
        scrollPanes.setHorizontalScrollBarPolicy(
                JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
            scrollPanes.setVerticalScrollBarPolicy(
                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        JTextPane textPane_1 = new JTextPane();
        scrollPanes.add(textPane_1);
        textPane_1.setBorder(BorderFactory.createLoweredBevelBorder());
        scrollPanes.setHorizontalScrollBarPolicy(
                JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
            scrollPanes.setVerticalScrollBarPolicy(
                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        JPanel bottomPanel = new JPanel();
        frame.getContentPane().add(bottomPanel, BorderLayout.SOUTH);
        bottomPanel.setLayout(new GridLayout(2, 1, 5, 0));
        bottomPanel.setBorder(BorderFactory.createLoweredBevelBorder());
        JTextPane bText = new JTextPane();
        bottomPanel.add(bText);
        bText.setBorder(BorderFactory.createLoweredBevelBorder());
        JLabel status = new JLabel("Status");
        bottomPanel.add(status);
        status.setHorizontalAlignment(JLabel.CENTER);
    }
}

Answer 1

textPane_0是JTextPane的实例，而不是JScrollPane，因此它没有setHorizontalScrollBarPolicy方法。

您可能想要将textPane_0和textPane_1包装在JScrollPane的新实例中，设置其滚动条属性并将其添加到框架中。

换句话说，使用

JTextPane textPane_0 = new JTextPane();
JScrollPane jScrollPane1 = new JScrollPane(textPane_0);//warp text pane
//and set properties of wrapper
jScrollPane1.setHorizontalScrollBarPolicy(
        JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
jScrollPane1.setVerticalScrollBarPolicy(
        JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
ScrollPanes.add(jScrollPane1);

JTextPane textPane_1 = new JTextPane();
JScrollPane jScrollPane2 = new JScrollPane(textPane_1);
jScrollPane2.setHorizontalScrollBarPolicy(
        JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
jScrollPane2.setVerticalScrollBarPolicy(
        JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
ScrollPanes.add(jScrollPane2);

演示：

class Demo {
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(500,400);
        JPanel ScrollPanes = new JPanel();
        frame.getContentPane().add(ScrollPanes, BorderLayout.CENTER);
        ScrollPanes.setLayout(new GridLayout(0, 2, 0, 0));
        JTextPane textPane_0 = new JTextPane();
        JScrollPane jScrollPane1 = new JScrollPane(textPane_0);
        jScrollPane1.setHorizontalScrollBarPolicy(
                JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
        jScrollPane1.setVerticalScrollBarPolicy(
                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        ScrollPanes.add(jScrollPane1);

        JTextPane textPane_1 = new JTextPane();
        JScrollPane jScrollPane2 = new JScrollPane(textPane_1);
        jScrollPane2.setHorizontalScrollBarPolicy(
                JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
        jScrollPane2.setVerticalScrollBarPolicy(
                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        ScrollPanes.add(jScrollPane2);

        frame.setVisible(true);

    }
}

Answer 2

JPanel ScrollPanes = new JPanel();

应为：

JScrollPane ScrollPanes = new JScrollPane();

或者更好，使用正确的命名法：

JScrollPane scrollPanes = new JScrollPane();

然后更改：

textPane_0.setHorizontalScrollBarPolicy(
    JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
textPane_0.setVerticalScrollBarPolicy(
    JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

收件人：

scrollPanes.setHorizontalScrollBarPolicy(
    JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
scrollPanes.setVerticalScrollBarPolicy(
    JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);