如何在JTextArea中读取最后一个单词或最新单词

Question

I am making a Source code Editor using JtextArea.In that I want to do the following task." While user typing on Editor window(JtextArea),each and every time the updated text(last word) should compare with the set of words in the database, if it matches any one of the word then the definition will be open in new popup frame." My coding is like following

String str = textarea.getText();
        Class.forName(driver).newInstance();
        conn = DriverManager.getConnection(url+dbName,userName,password);
        String stm="select url from pingatabl where functn=?";
        PreparedStatement st = conn.prepareStatement(stm);
        st.setString(1, str);
         //Excuting Query
        ResultSet rs = st.executeQuery();
        if (rs.next()) {
        String s = rs.getString(1);
        //Sets Records in frame
        JFrame fm = new JFrame();
        fm.setVisible(true);
        fm.setSize(500,750);
        JEditorPane jm = new JEditorPane();
        fm.add(jm);
        jm.setPage(ClassLoader.getSystemResource(s));

In the above coding String str = textarea.getText(); reads all the text in the textarea.. but i need to get last word only. How can i get latest word from JTextArea..

Answer 1

Use a DocumentListener to monitor for changes to the text component and use javax.swing.text.Utilities to calculate the start/end index of the word in the Document , from which you can the extract the result

import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.Utilities;

public class TheLastWord {

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

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

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            setLayout(new BorderLayout());
            JTextArea ta = new JTextArea(10, 20);
            add(new JScrollPane(ta));
            JLabel lastWord = new JLabel("...");
            add(lastWord, BorderLayout.SOUTH);

            ta.getDocument().addDocumentListener(new DocumentListener() {

                @Override
                public void insertUpdate(DocumentEvent e) {
                    checkLastWord();
                }

                @Override
                public void removeUpdate(DocumentEvent e) {
                    checkLastWord();
                }

                @Override
                public void changedUpdate(DocumentEvent e) {
                    checkLastWord();
                }

                protected void checkLastWord() {
                    try {
                        int start = Utilities.getWordStart(ta, ta.getCaretPosition());
                        int end = Utilities.getWordEnd(ta, ta.getCaretPosition());
                        String text = ta.getDocument().getText(start, end - start);
                        lastWord.setText(text);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            });
        }

    }

}

Answer 2

You can use following code block if you want to get the last word in the testarea

String[] wordsArray = textarea.getText().split("\\s+");
String lastWord = wordsArray[wordsArray.length - 1];

But if you want to get the last updated word then you have to use a Listener for that. Check on DocumentListener and DocumentEvent http://docs.oracle.com/javase/7/docs/api/javax/swing/event/DocumentListener.html http://docs.oracle.com/javase/7/docs/api/javax/swing/event/DocumentEvent.html

Answer 3

To get the last line in your JEditorPane, split the text in the editor on \\n as shown below:

String text = editor.getText();

String[] lines = text.split("\n");

String lastLine = lines[lines.length-1]; System.out.println("Last line: " + lastLine);

Similarly, to get the last word, split the last line on space.

Answer 4

Here a code of method that returns the last word of a text

   public static String getLastWord(String s) {
    int endOfLine = s.length() - 1;
    boolean start = false;
    while (!start && endOfLine >= 0) {
        if (!Character.isLetter(s.charAt(endOfLine))) {
            endOfLine--;
        } else {
            start = true;
        }
    }
    final StringBuilder lastWord = new StringBuilder("");
    while (start && endOfLine >= 0) {
        if (!Character.isLetter(s.charAt(endOfLine))) {
            start = false;
        } else {
            lastWord.insert(0, s.charAt(endOfLine));
            endOfLine--;
        }
    }
    return lastWord.toString();

}