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