Java - 滚动到 JTextArea 中的特定文本 [英] Java - Scroll to specific text inside JTextArea

问题描述

我正在尝试在我正在编写的当前程序中实现一个功能，我想学习如何向下滚动到 JTextArea 中的特定文本.例如，假设我有以下内容:

I'm trying to implement a feature inside the current program that I'm writing and I wanna learn how to scroll down to specific text inside a JTextArea. For example, lets say I have the following:

JTextArea area = new JTextArea(someReallyLongString);

someReallyLongString 将代表一个段落，或一段非常大的文本(其中垂直滚动条是可见的).所以我要做的是向下滚动到该文本区域内的特定文本.例如，假设 someReallyLongString 在滚动条中间附近包含单词the"(意味着该单词不可见)，我将如何向下滚动到该特定文本?

someReallyLongString would represent a paragraph, or a very large piece of text (in which the vertical scrollbar would be visible). And so what I am trying to do is scroll down to specific text within that text area. For example, lets say someReallyLongString contained the word "the" near the middle of the scrollbar (meaning this word is not visible), how would I scroll down to that specific text?

谢谢，任何帮助将不胜感激.

Thanks, any help would be greatly appreciating.

推荐答案

这是一个非常基本的例子.这基本上是遍历文档以找到单词在文档中的位置，并确保将文本移动到可视区域.

This is a VERY basic example. This basically walks the document to find the position of the word within the document and ensures that the text is moved to the viewable area.

它也突出了比赛

public class MoveToText {

    public static void main(String[] args) {
        new MoveToText();
    }

    public MoveToText() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new FindTextPane());
                frame.setSize(400, 400);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class FindTextPane extends JPanel {

        private JTextField findField;
        private JButton findButton;
        private JTextArea textArea;
        private int pos = 0;

        public FindTextPane() {
            setLayout(new BorderLayout());
            findButton = new JButton("Next");
            findField = new JTextField("Java", 10);
            textArea = new JTextArea();
            textArea.setWrapStyleWord(true);
            textArea.setLineWrap(true);

            Reader reader = null;
            try {
                reader = new FileReader(new File("Java.txt"));
                textArea.read(reader, null);
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                try {
                    reader.close();
                } catch (Exception e) {
                }
            }

            JPanel header = new JPanel(new GridBagLayout());

            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridx = 0;
            gbc.gridy = 0;
            gbc.anchor = GridBagConstraints.WEST;
            header.add(findField, gbc);
            gbc.gridx++;
            header.add(findButton, gbc);

            add(header, BorderLayout.NORTH);
            add(new JScrollPane(textArea));

            findButton.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    // Get the text to find...convert it to lower case for eaiser comparision
                    String find = findField.getText().toLowerCase();
                    // Focus the text area, otherwise the highlighting won't show up
                    textArea.requestFocusInWindow();
                    // Make sure we have a valid search term
                    if (find != null && find.length() > 0) {
                        Document document = textArea.getDocument();
                        int findLength = find.length();
                        try {
                            boolean found = false;
                            // Rest the search position if we're at the end of the document
                            if (pos + findLength > document.getLength()) {
                                pos = 0;
                            }
                            // While we haven't reached the end...
                            // "<=" Correction
                            while (pos + findLength <= document.getLength()) {
                                // Extract the text from teh docuemnt
                                String match = document.getText(pos, findLength).toLowerCase();
                                // Check to see if it matches or request
                                if (match.equals(find)) {
                                    found = true;
                                    break;
                                }
                                pos++;
                            }

                            // Did we find something...
                            if (found) {
                                // Get the rectangle of the where the text would be visible...
                                Rectangle viewRect = textArea.modelToView(pos);
                                // Scroll to make the rectangle visible
                                textArea.scrollRectToVisible(viewRect);
                                // Highlight the text
                                textArea.setCaretPosition(pos + findLength);
                                textArea.moveCaretPosition(pos);
                                // Move the search position beyond the current match
                                pos += findLength;
                            }

                        } catch (Exception exp) {
                            exp.printStackTrace();
                        }

                    }
                }
            });

        }
    }
}

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