swing - jScrollPane 保持捕捉到底部

Question

我试图从数据库中检索数据并使用带有 scrollPane 的 textArea 进行显示。这是我的代码：

public class eForumThreadContent {

private JFrame jFrame = null; // @jve:decl-index=0:visual-constraint="74,36"
private JPanel jContentPane = null;
private JLabel jLoginLink = null;
private JTextField jTextField_search = null;
private JButton jButtonSearch = null;
private JLabel jLabel_sessionborder = null;
private JButton jButton_home = null;
private JLabel jLabel_searchBackgroundColor = null;
private JButton jButton_signOut = null;
private JButton jButton_postNewThread = null;
private JButton jButton_back = null;
private JLabel jLabel_replyBy = null;
private JLabel jLabel_username = null;
private JLabel jLabel_reply = null;
private JTextArea jTextArea_reply = null;
private JButton jButton_postReply = null;
private JTable jTableComment = null;
private JScrollPane jScrollPaneComment = null;
private JButton jButton_bookmark = null;
private JButton jButton_myAcc = null;
private  String userName; // @jve:decl-index=0:
DBController db = new DBController();  //  @jve:decl-index=0:
private  int topicId;
private JLabel jLabel_topicTitle = null;
private JLabel jLabel_topicBy = null;
private JLabel jLabel_separator = null;
private JLabel jLabel_title = null;
private JScrollPane jScrollPane_areaScrollPane = null;
private JTextArea jTextArea_content = null;
private JScrollPane jScrollPane_descContent = null;
/**
 * This method initializes jFrame
 * 
 * @return javax.swing.JFrame
 */
JFrame getJFrame() {
    if (jFrame == null) {
        jFrame = new JFrame();
        jFrame.setSize(new Dimension(946, 762));
        jFrame.setContentPane(getJContentPane());
        jFrame.setTitle("eForum");
    }
    return jFrame;
}

/**
 * This method initializes jContentPane
 * 
 * @return javax.swing.JPanel
 */
private JPanel getJContentPane() {
    if (jContentPane == null) {
        jLabel_title = new JLabel();
        jLabel_title.setBounds(new Rectangle(75, 167, 77, 51));
        jLabel_title.setFont(new Font("Dialog", Font.PLAIN, 24));
        jLabel_title.setHorizontalAlignment(SwingConstants.LEFT);
        jLabel_title.setText("Title : ");
        jLabel_separator = new JLabel();
        jLabel_separator.setBounds(new Rectangle(73, 278, 784, 8));
        jLabel_separator.setBackground(new Color(102,102,102));
        jLabel_separator.setOpaque(true);
        jLabel_topicBy = new JLabel();
        jLabel_topicBy.setBounds(new Rectangle(761, 217, 175, 41));
        jLabel_topicBy.setFont(new Font("Dialog", Font.PLAIN, 18));
        jLabel_topicTitle = new JLabel();
        jLabel_topicTitle.setBounds(new Rectangle(161, 167, 757, 50));
        jLabel_topicTitle.setFont(new Font("Dialog", Font.PLAIN, 24));
        jLabel_reply = new JLabel();
        jLabel_reply.setBounds(new Rectangle(106, 528, 132, 37));
        jLabel_reply.setFont(new Font("Dialog", Font.PLAIN, 24));
        jLabel_reply.setText("Comment");
        jLabel_username = new JLabel();
        jLabel_username.setBounds(new Rectangle(256, 483, 315, 32));
        jLabel_username.setFont(new Font("Dialog", Font.PLAIN, 24));
        jLabel_username.setText(userName);
        jLabel_replyBy = new JLabel();
        jLabel_replyBy.setBounds(new Rectangle(106, 481, 137, 38));
        jLabel_replyBy.setFont(new Font("Dialog", Font.PLAIN, 24));
        jLabel_replyBy.setText("Reply by");
        jLabel_searchBackgroundColor = new JLabel();
        jLabel_searchBackgroundColor
                .setBounds(new Rectangle(2, 64, 930, 44));
        jLabel_searchBackgroundColor
                .setBackground(new Color(102, 102, 102));
        jLabel_searchBackgroundColor.setOpaque(true);
        jLabel_sessionborder = new JLabel();
        jLabel_sessionborder.setBounds(new Rectangle(-1, 40, 930, 25));
        jLabel_sessionborder.setBorder(BorderFactory.createMatteBorder(0,
                0, 1, 0, Color.black));
        jLabel_sessionborder.setText("");
        jLoginLink = new JLabel();
        jLoginLink.setBounds(new Rectangle(34, 34, 259, 25));
        jLoginLink.setBorder(BorderFactory.createMatteBorder(0, 0, 0, 0,
                Color.black));
        jLoginLink.setFont(new Font("Dialog", Font.PLAIN, 24));
        jLoginLink.setText("Logged in as " + userName);
        jContentPane = new JPanel();
        jContentPane.setLayout(null);
        jContentPane.setBackground(Color.white);
        jContentPane.add(jLoginLink, null);
        jContentPane.add(getJTextField_search(), null);
        jContentPane.add(getJButtonSearch(), null);
        jContentPane.add(jLabel_sessionborder, null);
        jContentPane.add(getJButton_home(), null);
        jContentPane.add(jLabel_searchBackgroundColor, null);
        jContentPane.add(getJButton_signOut(), null);
        jContentPane.add(getJButton_postNewThread(), null);
        jContentPane.add(getJButton_back(), null);
        jContentPane.add(jLabel_replyBy, null);
        jContentPane.add(jLabel_username, null);
        jContentPane.add(jLabel_reply, null);
        jContentPane.add(getJTextArea_reply(), null);
        jContentPane.add(getJButton_postReply(), null);
        jContentPane.add(getJScrollPaneComment(), null);
        jContentPane.add(getJButton_bookmark(), null);
        jContentPane.add(getJButton_myAcc(), null);
        jContentPane.add(jLabel_topicTitle, null);
        jContentPane.add(jLabel_topicBy, null);
        jContentPane.add(jLabel_separator, null);
        jContentPane.add(jLabel_title, null);
        jContentPane.add(getJScrollPane_areaScrollPane(), null);
        jContentPane.add(getJTextArea_content(), null);
        jContentPane.add(getJScrollPane_descContent(), null);
        SetUpTopicDetails();
    }
    return jContentPane;
}

/**
 * This constructor take in the userName from eForumLogin page. The username
 * will be display in jLoginLink.
 * 
 * @param userName
 */
public eForumThreadContent(String userName, int topicId) {
    this.userName = userName;
    this.topicId = topicId;

}

/**
 * This method initializes jTextField_search
 * 
 * @return javax.swing.JTextField
 */
private JTextField getJTextField_search() {
    if (jTextField_search == null) {
        jTextField_search = new JTextField(50);
        jTextField_search.setDocument (new JTextFieldLimit(50));
        jTextField_search.setBounds(new Rectangle(500, 75, 285, 29));
        jTextField_search.setFont(new Font("Dialog", Font.PLAIN, 24));
    }
    return jTextField_search;
}

/**
 * This method initializes jButtonSearch submitSearch is called when this
 * button is on click.
 * 
 * @return javax.swing.JButton
 */
private JButton getJButtonSearch() {
    if (jButtonSearch == null) {
        jButtonSearch = new JButton();
        jButtonSearch.setBounds(new Rectangle(797, 73, 114, 28));
        jButtonSearch.setFont(new Font("Dialog", Font.PLAIN, 24));
        jButtonSearch.setText("Search");
        jButtonSearch
                .addActionListener(new java.awt.event.ActionListener() {
                    public void actionPerformed(java.awt.event.ActionEvent e) {
                        submitSearch(e);
                    }
                });
    }
    return jButtonSearch;
}


public void submitSearch(ActionEvent e) {
    String search = jTextField_search.getText();
    if (search.equals("")) {
        JOptionPane.showMessageDialog(null,
                "Please enter keyword to search");
    } else {
        eForumSearch searchResult = new eForumSearch(userName, search);
        if (searchResult.searchKeyword() == true) {
            getJFrame().dispose();
            eForumSearchResult myWindow = new eForumSearchResult(userName,
                    search);
            myWindow.getJFrame().setVisible(true);
        } else {
            JOptionPane.showMessageDialog(null, "No results found");
        }
    }
}

/**
 * This method initializes jButton_home
 * 
 * @return javax.swing.JButton
 */
private JButton getJButton_home() {
    if (jButton_home == null) {
        jButton_home = new JButton();
        jButton_home.setBounds(new Rectangle(819, 2, 94, 60));
        jButton_home.setBackground(Color.white);
        jButton_home.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));
        jButton_home.setIcon(new ImageIcon(getClass().getResource(
                "/Home.png")));
        jButton_home
        .addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent e) {
                getJFrame().dispose();
                kioskHomepage myWindow = new kioskHomepage();
                myWindow.getJFrame().setVisible(true);
            }
        });
    }
    return jButton_home;
}

private JButton getJButton_signOut() {
    if (jButton_signOut == null) {
        jButton_signOut = new JButton();
        jButton_signOut.setBounds(new Rectangle(297, 35, 139, 24));
        jButton_signOut.setText("Sign out");
        jButton_signOut.setBorderPainted(false);
        jButton_signOut.setOpaque(false);
        jButton_signOut.setHorizontalAlignment(SwingConstants.LEFT);
        jButton_signOut.setFont(new Font("Dialog", Font.PLAIN, 24));
        jButton_signOut.setBackground(Color.lightGray);
        jButton_signOut
                .addActionListener(new java.awt.event.ActionListener() {
                    public void actionPerformed(java.awt.event.ActionEvent e) {
                        getJFrame().dispose();
                        eForumSignOut myWindow = new eForumSignOut(userName);
                        myWindow.getJFrame().setVisible(true);

                    }
                });
    }
    return jButton_signOut;
}

private JButton getJButton_postNewThread() {
    if (jButton_postNewThread == null) {
        jButton_postNewThread = new JButton();
        jButton_postNewThread.setBounds(new Rectangle(682, 118, 230, 36));
        jButton_postNewThread.setFont(new Font("Dialog", Font.PLAIN, 24));
        jButton_postNewThread.setText("Post New Thread");
        jButton_postNewThread
                .addActionListener(new java.awt.event.ActionListener() {
                    public void actionPerformed(java.awt.event.ActionEvent e) {
                        getJFrame().dispose();
                        eForumPostThread myWindow = new eForumPostThread(
                                userName);
                        myWindow.getJFrame().setVisible(true);
                    }
                });
    }
    return jButton_postNewThread;
}


public void SetUpTopicDetails() {
    db.setUp("IT Innovation Project");
    String sql = "Select topic_title,topic_description,topic_by from forumTopics WHERE topic_id = "
            + topicId + "";
    ResultSet resultSet = null;
    resultSet = db.readRequest(sql);
    try {
        while (resultSet.next()) {
            jLabel_topicTitle.setText(resultSet.getString("topic_title"));
            jTextArea_content.setText(resultSet.getString("topic_description"));
            jLabel_topicBy.setText(resultSet.getString("topic_by"));
        }
        resultSet.close();
    } catch (Exception e) {
        System.out.println(e);
    }
}

private JButton getJButton_back() {
    if (jButton_back == null) {
        jButton_back = new JButton();
        jButton_back.setBounds(new Rectangle(735, 679, 166, 36));
        jButton_back.setText("Back");
        jButton_back.setFont(new Font("Dialog", Font.PLAIN, 24));
        jButton_back.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent e) {
                getJFrame().dispose();
                eForumMainpage myWindow = new eForumMainpage(userName);
                myWindow.getJFrame().setVisible(true);
            }
        });
    }
    return jButton_back;
}

/**
 * This method initializes jTextArea_reply
 * 
 * @return javax.swing.JTextArea
 */
private JTextArea getJTextArea_reply() {
    if (jTextArea_reply == null) {
        jTextArea_reply = new JTextArea();
        jTextArea_reply.setBounds(new Rectangle(256, 525, 573, 130));
        jTextArea_reply.setFont(new Font("Dialog", Font.PLAIN, 24));
        jTextArea_reply.setLineWrap(true);
    }
    return jTextArea_reply;
}

private JButton getJButton_postReply() {
    if (jButton_postReply == null) {
        jButton_postReply = new JButton();
        jButton_postReply.setBounds(new Rectangle(567, 678, 155, 36));
        jButton_postReply.setFont(new Font("Dialog", Font.PLAIN, 24));
        jButton_postReply.setText("Post reply");
        jButton_postReply
                .addActionListener(new java.awt.event.ActionListener() {
                    public void actionPerformed(java.awt.event.ActionEvent e) {
                        submitReply(e);
                    }
                });
    }
    return jButton_postReply;
}

public void submitReply(ActionEvent e) {
    String replyBy = userName;
    String reply = jTextArea_reply.getText();
    if (reply.equals("")) {
        JOptionPane.showMessageDialog(null, "Comment cannot leave blank");
    } else {
        eForumTopics comment = new eForumTopics(replyBy, reply);
        if (comment.createComment() == true) {
            JOptionPane
                    .showMessageDialog(null,
                            "Reply submitted successfully.");
            SetUpJTableComment();
            jTextArea_reply.setText("");
        }
    }

}

private JTable getJTableComment() {
    String header[] = { "Comment", "Reply By" };
    if (jTableComment == null) {
    DefaultTableModel tableModel1 = (DefaultTableModel) jTableComment
            .getModel();
    tableModel1.setColumnIdentifiers(header);

    jTableComment.getColumnModel().getColumn(0).setMinWidth(685);
    jTableComment.getColumnModel().getColumn(0).setMaxWidth(750);

    jTableComment.getColumnModel().getColumn(1).setMinWidth(97);
    jTableComment.getColumnModel().getColumn(1).setMaxWidth(100);

    return jTableComment;
}

public void SetUpJTableComment() {
    DefaultTableModel tableModel1 = (DefaultTableModel) jTableComment
            .getModel();
    String[] data = new String[3];
    db.setUp("IT Innovation Project");
    String sql = "Select reply_content,reply_by from forumReplies WHERE reply_topic = "
            + topicId + "";
    ResultSet resultSet = null;
    resultSet = db.readRequest(sql);
    tableModel1.getDataVector().removeAllElements();

    try {
        while (resultSet.next()) {
            data[0] = resultSet.getString("reply_content");
            data[1] = resultSet.getString("reply_by");
            tableModel1.addRow(data);
        }
        resultSet.close();
    } catch (Exception e) {
        System.out.println(e);
    }
}

private JScrollPane getJScrollPaneComment() {
    if (jScrollPaneComment == null) {
        jScrollPaneComment = new JScrollPane();
        jScrollPaneComment.setBounds(new Rectangle(75, 290, 785, 175));
        jScrollPaneComment.setBorder(BorderFactory.createEmptyBorder());
        jScrollPaneComment.setViewportView(getJTableComment());
    }
    SetUpJTableComment();
    return jScrollPaneComment;
}

private JButton getJButton_bookmark() {
    if (jButton_bookmark == null) {
        jButton_bookmark = new JButton();
        jButton_bookmark.setBounds(new Rectangle(487, 119, 186, 36));
        jButton_bookmark.setFont(new Font("Dialog", Font.PLAIN, 24));
        jButton_bookmark.setText("Bookmark");
        jButton_bookmark
                .addActionListener(new java.awt.event.ActionListener() {
                    public void actionPerformed(java.awt.event.ActionEvent e) {
                        submitBookmark(e);
                    }
                });
    }
    return jButton_bookmark;
}

public void submitBookmark(ActionEvent e) {
    String bookmarkBy = userName;
    eForumTopics bookmark = new eForumTopics(bookmarkBy);
    if (bookmark.bookmarkThread() == true) {
        JOptionPane.showMessageDialog(null, "Thread has been bookmarked.");
    }
}

private JButton getJButton_myAcc() {
    if (jButton_myAcc == null) {
        jButton_myAcc = new JButton();
        jButton_myAcc.setBounds(new Rectangle(427, 27, 175, 41));
        jButton_myAcc.setText("My account");
        jButton_myAcc.setBorderPainted(false);
        jButton_myAcc.setOpaque(false);
        jButton_myAcc.setHorizontalAlignment(SwingConstants.LEFT);
        jButton_myAcc.setFont(new Font("Dialog", Font.PLAIN, 24));
        jButton_myAcc.setBackground(Color.lightGray);
        jButton_myAcc
                .addActionListener(new java.awt.event.ActionListener() {
                    public void actionPerformed(java.awt.event.ActionEvent e) {
                        getJFrame().dispose();
                        eForumMyAcc myWindow = new eForumMyAcc(userName);
                        myWindow.getJFrame().setVisible(true);
                    }
                });
    }
    return jButton_myAcc;
}

private JScrollPane getJScrollPane_areaScrollPane() {
    if (jScrollPane_areaScrollPane == null) {
        jScrollPane_areaScrollPane = new JScrollPane(jTextArea_reply);
        jScrollPane_areaScrollPane.setBounds(new Rectangle(257, 527, 598, 125));

    }
    return jScrollPane_areaScrollPane;
}

/**
 * This method initializes jTextArea_content    
 *  
 * @return javax.swing.JTextArea    
 */
private JTextArea getJTextArea_content() {
    if (jTextArea_content == null) {
        jTextArea_content = new JTextArea();
        jTextArea_content.setBounds(new Rectangle(75, 224, 678, 47));
    return jTextArea_content;
}

/**
 * This method initializes jScrollPane_descContent  
 *  
 * @return javax.swing.JScrollPane  
 */
private JScrollPane getJScrollPane_descContent() {
    if (jScrollPane_descContent == null) {
        jScrollPane_descContent = new JScrollPane(jTextArea_content);
        jScrollPane_descContent.setBounds(new Rectangle(75, 224, 660, 47));
    }
    return jScrollPane_descContent;
}

}

但是，滚动条会一直捕捉到 textArea 的底部，而不是 textArea 的前几行。提前致谢。

score 0 · Accepted Answer

这就是我所有的代码。没有其他的。其余代码与此无关。

然而，当我使用您迄今为止提供给我们的代码运行我的SSCCE时，它就像一个魅力：

import java.awt.Rectangle;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;

public class TestTextArea3 {

    private static final String TEXT = "This \r\n" + "    Is\r\n" + "    A\r\n" + "    Testing\r\n" + "    To\r\n" + "    Test\r\n"
            + "    ScrollPane.";

    private JTextArea jTextArea_content;
    private JScrollPane jScrollPane_descContent;

    private void initUI() {
        JFrame frame = new JFrame(TestTextArea3.class.getSimpleName());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        getJTextArea_content().setText(TEXT);
        frame.add(getJScrollPane_descContent());
        frame.pack();
        frame.setVisible(true);
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                getJTextArea_content().scrollRectToVisible(new Rectangle());
            }
        });
    }

    private JTextArea getJTextArea_content() {
        if (jTextArea_content == null) {
            // Changed the number of rows so activate scrolling
            jTextArea_content = new JTextArea(3, 30);
            jTextArea_content.setBounds(new Rectangle(75, 224, 678, 47));
        }
        return jTextArea_content;
    }

    private JScrollPane getJScrollPane_descContent() {
        if (jScrollPane_descContent == null) {
            jScrollPane_descContent = new JScrollPane(getJTextArea_content());
            jScrollPane_descContent.setBounds(new Rectangle(75, 224, 660, 47));
        }
        return jScrollPane_descContent;
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new TestTextArea3().initUI();
            }
        });
    }

}

swing - jScrollPane 保持捕捉到底部

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