How to change highlighting color in Java Swing TextArea? And also, change the beginning of text corresponding to the highlighting location

Question

Problem 1: BY using defaulthighlighter, I can make the focused lines change to blue. Now I want to change it to other colors. Do anyone know how to change this parameter? --- solved

Problem 2: pos is the beginning index of my substring which I want to highlight. I use setCaretPosition(pos); to update the showing content. But it always appears at the bottom of the window. I want to have it at the top. Could anyone tell me how to deal with that?

I use one demo to show my problem:

import java.awt.Color;
import java.net.MalformedURLException;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;

public class Test {
    public static void main(final String[] args) throws MalformedURLException {
        SwingUtilities.invokeLater(new Runnable() {

        @Override
        public void run() {
            try {
                init();
            } catch (BadLocationException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
    });
}

private static void init() throws BadLocationException {
    JFrame frame = new JFrame();
    final JTextArea textArea = new JTextArea();
    JScrollPane pane = new JScrollPane(textArea);
    textArea.setText("Something. Something else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Samething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Sbmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Scmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Sdmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Semething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Sfmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Sgmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n");
    textArea.setSelectionColor(Color.RED);
    frame.add(pane);
    frame.setSize(300, 120);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);

    String turnToString2 = "Sdmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla";
    int pos2 = textArea.getText().indexOf(turnToString2);
    textArea.getHighlighter().addHighlight(pos2,
            pos2 + turnToString2.length(),
            new DefaultHighlighter.DefaultHighlightPainter(Color.yellow));
    textArea.setCaretPosition(pos2);

The result is :

I want it to be at the right top of the screen but in this code, it is shown at the bottom of the scrollpane. Can anyone know how to change this? THanks.

Demona

Check this out my latest edit, is this what you wanted ? – Humility

@nIcEcOw Hi, THanks so much for your edit. I now use Guillaume Polet's demo code to illustrate my problem. Could you run it and have a look at it? Thanks. – Demona

I had done that a bit, try to test it, by running the latest code, I hope that might can help :-) – Humility

Answer 1

You can achieve this, though not directly, since you have to save the reference to the Highlight that you had added to the said line, hence you have to traverse through all the Highlights to remove the one you want, have a look at the program attached, might be this will help you to attain what you so desire :

LATEST EDIT : NEW CODE, REMOVED SOME BUGS AND SEEMS LIKE ADDED THE DESIRED FUNCTIONALITY RELATED TO SETTING CARET POSITION

import java.awt.*;
import java.awt.event.*;
import java.util.Map;
import java.util.HashMap;
import javax.swing.*;
import javax.swing.text.*;

public class TextHighlight
{
    private JTextArea tarea;
    private JComboBox cbox;
    private JTextField lineField;
    private String[] colourNames = {"RED", "ORANGE", "CYAN"};

    private Highlighter.HighlightPainter redPainter;
    private Highlighter.HighlightPainter orangePainter;
    private Highlighter.HighlightPainter cyanPainter;   

    private int firstUpdateIndex;
    private int counter;

    private Map<Integer, Highlighter.Highlight> highlights = new HashMap<Integer, Highlighter.Highlight>();

    public TextHighlight()
    {
        redPainter = new DefaultHighlighter.DefaultHighlightPainter(Color.RED);
        orangePainter = new DefaultHighlighter.DefaultHighlightPainter(Color.ORANGE);
        cyanPainter = new DefaultHighlighter.DefaultHighlightPainter(Color.CYAN);

        firstUpdateIndex = -1;
        counter = 0;
    }

    private void createAndDisplayGUI()
    {
        final JFrame frame = new JFrame("Text HIGHLIGHT");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        JPanel contentPane = new JPanel();
        contentPane.setBorder(BorderFactory.createTitledBorder(
                BorderFactory.createEmptyBorder(5, 5, 5, 5), "Highlighter JTextArea"));

        tarea = new JTextArea(10, 10);
        JScrollPane scrollPane = new JScrollPane(tarea);
        contentPane.add(scrollPane);

        JButton remHighButton = new JButton("REMOVE HIGHLIGHT");
        remHighButton.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent ae)
            {
                String input = JOptionPane.showInputDialog(frame, "Please Enter Start Index : "
                                                        , "Highlighting Options : "
                                                        , JOptionPane.PLAIN_MESSAGE);

                if (input != null && (highlights.size() > 0))
                {               
                    int startIndex = Integer.parseInt(input.trim());
                    Highlighter highlighter = tarea.getHighlighter();
                    highlighter.removeHighlight(highlights.get(startIndex));
                    tarea.setCaretPosition(startIndex);
                    tarea.requestFocusInWindow();
                    highlights.remove(startIndex);
                }
            }
        });

        JButton button = new JButton("HIGHLIGHT TEXT");
        button.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent ae)
            {
                String text = null;
                text = tarea.getSelectedText();
                if (text != null && text.length() > 0)
                {
                    int startIndex = tarea.getText().indexOf(text);
                    int endIndex = startIndex + text.length();
                    Highlighter highlighter = tarea.getHighlighter();

                    int selection = JOptionPane.showConfirmDialog(
                                            frame, getOptionPanel(), "Highlight Colour : "
                                                , JOptionPane.OK_CANCEL_OPTION
                                                , JOptionPane.PLAIN_MESSAGE);

                    System.out.println("TEXT : " + text);
                    System.out.println("START INDEX : " + startIndex);
                    System.out.println("END INDEX : " + endIndex);

                    if (selection == JOptionPane.OK_OPTION)
                    {
                        String colour = (String) cbox.getSelectedItem();
                        try
                        {
                            if (colour == colourNames[0])
                            {
                                System.out.println("Colour Selected : " + colour);
                                highlighter.addHighlight(startIndex, endIndex, redPainter);
                            }
                            else if (colour == colourNames[1])
                            {
                                System.out.println("Colour Selected : " + colour);
                                highlighter.addHighlight(startIndex, endIndex, orangePainter);
                            }
                            else if (colour == colourNames[2])
                            {
                                System.out.println("Colour Selected : " + colour);
                                highlighter.addHighlight(startIndex, endIndex, cyanPainter);
                            }
                            Highlighter.Highlight[] highlightIndex = highlighter.getHighlights();
                            System.out.println("Lengh of Highlights used : " + highlightIndex.length);
                            highlights.put(startIndex, highlightIndex[highlightIndex.length - 1]);
                        }
                        catch(BadLocationException ble)
                        {
                            ble.printStackTrace();
                        }
                    }
                    else if (selection == JOptionPane.CANCEL_OPTION)
                    {
                        System.out.println("CANCEL BUTTON PRESSED.");
                    }
                    else if (selection == JOptionPane.CLOSED_OPTION)
                    {
                        System.out.println("JOPTIONPANE CLOSED DELIBERATELY.");
                    }                   
                }
            }
        });

        frame.add(remHighButton, BorderLayout.PAGE_START);
        frame.add(contentPane, BorderLayout.CENTER);
        frame.add(button, BorderLayout.PAGE_END);

        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    private JPanel getOptionPanel()
    {
        JPanel panel = new JPanel();
        panel.setBorder(BorderFactory.createTitledBorder(
                        BorderFactory.createLineBorder(Color.DARK_GRAY, 2), "COLOUR SELECTION"));
        panel.setLayout(new GridLayout(0, 2, 5, 5));

        JLabel colourLabel = new JLabel("Select One Colour : ");
        cbox = new JComboBox(colourNames);

        panel.add(colourLabel);
        panel.add(cbox);

        return panel;
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new TextHighlight().createAndDisplayGUI();
            }
        });
    }
}

OUTPUT :

BEGIN :

HIGHLIGHT FIRST LINE SECOND

REMOVED HIGHLIGHT

HIGHLIGHTING THE SAME LINE WITH DIFFERENT COLOUR

LATEST EDIT in lines with the SAMPLE CODE in the QUESTION

import java.awt.*;
import java.net.MalformedURLException;

import javax.swing.*;
import javax.swing.text.*;

public class Test {
    public static void main(final String[] args) throws MalformedURLException {
        SwingUtilities.invokeLater(new Runnable() {

        @Override
        public void run() {
            try {
                init();
            } catch (BadLocationException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
    });
}

private static void init() throws BadLocationException {
    JFrame frame = new JFrame();
    final JTextArea textArea = new JTextArea();
    JScrollPane pane = new JScrollPane(textArea);
    textArea.setText("Something. Something else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Samething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Sbmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Scmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Sdmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Semething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Sfmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nSomething. Sgmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n");
    textArea.setSelectionColor(Color.RED);
    frame.add(pane);
    frame.setSize(300, 120);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);

    String turnToString2 = "Sdmething else.\nA second line\na third line"
            + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla";
    int pos2 = textArea.getText().indexOf(turnToString2);
    Rectangle startIndex = textArea.modelToView(pos2);
    textArea.getHighlighter().addHighlight(pos2,
            pos2 + turnToString2.length(),
            new DefaultHighlighter.DefaultHighlightPainter(Color.yellow));    
    int y = startIndex.y + (pane.getHeight() - 10);
    System.out.println("Pane Height : " + pane.getHeight());
    System.out.println("X : " + startIndex.x);
    System.out.println("Y : " + y);
    System.out.println("Y (pos2) : " + startIndex.y);
    textArea.setCaretPosition(textArea.viewToModel(new Point(startIndex.x, y)));
    pane.scrollRectToVisible(new Rectangle(startIndex.x, y));
    }
}

Here is the OUTPUT :

Humility

Thanks so much for your example! I do learn sth.. However, do you have a solution for my problem 2? Specifically, suppose I have many lines which need the scrollPane generate scrollbar automatically. If I hightlight one line, I want the first line appeared in the window is the highlighting one. I use : windowText.setCaretPosition(pos); where the pos is the Highlighting substring's index. But it didn't work properly. THe highlighting line will appear at the end of this window. – Demona

This thing is a bit tricky, for me atleast, since if I do my changes then I can bring the cursor to the first edit, without touching JScrollPane, with Mouse or whatever, though If I manually change the position of the JScrollPane, then it never moves automatically :(, looking into that thingy – Humility

@nlcE cOw Thanks. I am not changing the position manually. Acutally my thing is I linked this Textarea With other panel. So when I click on some line, I want the same line highlighted in this TextArea as well. So I need the Caret to make the highlighting lines shown at the top, not only just shown in the window, which is not enough. It doesn't make sense the SetCaretPosition(Position) not working. It should bring the positioning line to the top.... – Demona

@Demona : " It should bring the positioning line to the top.... .", No setCaretPosition(...) will just change the position of the Caret, not the text. You have to insert the text yourself, by selecting it from a specified location and inserting at another location (at the TOP, I guess in your case ) – Humility

@nIcE cOw you have to remove from Highlighter[] and inside loop highlighter.removeHighlight() +1 – Free

@GuillaumePolet : Thankyou for that, same thing goes for your example too :-) – Humility

@Free : Sorry this time could't understand you, had I done something wrong here in my example ? :( – Humility

@Free : But those examples all deal with removing all highlights from the said Document, but not just one :( – Humility

@Demona : Though in this latest Edit, You are suppose to make the selection manually, by selecting text and then for removing the highlight, you have to provide the starting index of the highlighted text. – Humility

Answer 2

To set the selection background color, use setSelectionColor (illustrated below but not used).

I don't really understand what you're saying with it always appears at the bottom of the window. I want to have it at the top but I am guessing (and I may be wrong here) that your textarea is in a scrollpane and that by highlighting the text it scrolls to the end of your selection, so I suggest to set the caret position after highlighting the text.

Here is a sample of what I understood. Let me know if this is not what you're looking for:

import java.awt.Color;
import java.net.MalformedURLException;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;

public class Test {
    public static void main(final String[] args) throws MalformedURLException {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                try {
                    init();
                } catch (BadLocationException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

            }
        });
    }

    private static void init() throws BadLocationException {
        JFrame frame = new JFrame();
        final JTextArea textArea = new JTextArea();
        JScrollPane pane = new JScrollPane(textArea);
        textArea.setText("Something. Something else.\nA second line\na third line"
                + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n"
                + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla\nBlabla\n");
        textArea.setSelectionColor(Color.RED);
        frame.add(pane);
        frame.setSize(300, 120);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
        String turnToString = "Something else.\nA second line\na third line"
                + "Blabla\nBlabla\nBlabla\nBlabla\nBlabla";
        final int pos = textArea.getText().indexOf(turnToString);
        textArea.getHighlighter().addHighlight(pos,
                pos + turnToString.length(),
                new DefaultHighlighter.DefaultHighlightPainter(Color.yellow));
        textArea.scrollRectToVisible(new Rectangle(0, 0, pane.getViewport().getWidth(), pane.getViewport().getHeight()));
            SwingUtilities.invokeLater(new Runnable() {
                    @Override
                    public void run() {
                        textArea.setCaretPosition(pos);
                    }
            });
    }
}

Epanodos

@Free hey, we meet again ;-) I actually misunderstood the question regarding highlighting and selecting. I am not sure what the OP is looking for. Anyway, I radically changed my answer thanks to your helpful comments. Cheers. – Epanodos

@GuillaumePolet Thanks for your answer. BY using DefaultHighlightPainter(Color.yellow) instead, the color can be manipulated. As for the caretPosition, my problem is when there are say 20 lines shown in the scrollPane, the highlighted 2 lines are shown at the bottom, which is supposed to be showned at the first two lines within the current window. Do you know what's wrong? – Demona

@Demona Take my code or the one from mKorbel and try to illustrate the problem you are having; the edit your question with that code. Without a complete code, we cannot guess what the problem could be. We both try to show you highlighting that works but there must be some differences that makes your code not work correctly – Epanodos

@GuillaumePolet Thanks you for your suggestion. I've done that. Could you have a look at it? – Demona

@Demona I edited my post with a solution to make the caret line the first line visible in the scrollpane. It is a bit of an ugly hack but it works nicely. I don't see any direct API method to find where the scroll needs to go. An alternate solution would be to access the UI of the TextComponent and ask the mapper the exact Rectangle of the caret location and then scroll directly to that rectangle. – Epanodos

Answer 3

I think that not accesible to change these methods for all JTextComponents in the case that is there used Highlighter, but is possible to change Foreground only

for example

import java.awt.*;
import javax.swing.*;
import javax.swing.text.DefaultHighlighter;

public class TextAreaLineHightLight {

    public static void main(String[] args) throws Exception {
        UIManager.put("TextArea.selectionBackground", Color.yellow);
        UIManager.put("TextArea.selectionForeground", Color.red);

        String string = "Lorem ipsum eum putant gubergren evertitur in, "
                + "no assueverit vituperatoribus eum. Ea cibo offendit vim, est et vivendum qualisque prodesset. "
                + "Vis doctus expetenda contentiones an, no ius mazim epicuri expetendis, "
                + "saperet salutandi forensibus ne usu. Ex fugit alterum usu. "
                + "His ignota cotidieque in, augue erroribus eam no.";
        JTextArea textArea = new JTextArea(string);
        textArea.setLineWrap(true);
        textArea.setWrapStyleWord(true);
        JScrollPane textAreaScroll = new JScrollPane(textArea);
        JFrame frame = new JFrame();
        frame.setLayout(new BorderLayout());
        frame.add(textAreaScroll, BorderLayout.CENTER);
        frame.setSize(400, 300);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
        String term = "qualisque prodesset. "
                + "Vis doctus expetenda contentiones an, no ius mazim epicuri expetendis";
        int termOffset = string.indexOf(term);
        Rectangle view = textArea.modelToView(termOffset);
        int startOffset = textArea.viewToModel(new Point(0, view.y));
        //int rowH = textArea.
        int endOffset = textArea.viewToModel(new Point(textArea.getSize().width, view.y));
        textArea.getHighlighter().addHighlight(startOffset, endOffset, new DefaultHighlighter.DefaultHighlightPainter(Color.YELLOW));
    }
}

with the same result for JTextPane

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

public class TextPaneHighlighting extends JFrame {

    private static final long serialVersionUID = 1L;
    private Highlighter.HighlightPainter cyanPainter;
    private Highlighter.HighlightPainter redPainter;

    public TextPaneHighlighting() {
        UIManager.put("TextPane.selectionBackground", Color.yellow);
        UIManager.put("TextPane.selectionForeground", Color.red);
        JTextPane textPane = new JTextPane();
        textPane.setText("one\ntwo\nthree\nfour\nfive\nsix\nseven\neight\n");
        JScrollPane scrollPane = new JScrollPane(textPane);
        getContentPane().add(scrollPane);//  Highlight some text
        cyanPainter = new DefaultHighlighter.DefaultHighlightPainter(Color.cyan);
        redPainter = new DefaultHighlighter.DefaultHighlightPainter(Color.red);
        try {
            textPane.getHighlighter().addHighlight(0, 3, DefaultHighlighter.DefaultPainter);
            textPane.getHighlighter().addHighlight(8, 14, cyanPainter);
            textPane.getHighlighter().addHighlight(19, 24, redPainter);
        } catch (BadLocationException ble) {
        }
    }

    public static void main(String[] args) {
        TextPaneHighlighting frame = new TextPaneHighlighting();
        frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
        frame.setSize(300, 200);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

Free

Why not using setSelectionColor and setSelectedTextColor to change the colors since they are available? – Epanodos

Thanks! Basically, you and Guillaume have the same solution - DefaultHighlightPainter(Color. XXX). – Demona

Answer 4

To solve 2) Use modelToView to get point of the first selected row. Then use scrollRectToVisible using the Point (NOTE: height of the rectangle must be your viewport height).

Groos

I had heard a lot about modelToView, seems like today I have walk straight through it to clear my doubt :-) +1 – Humility