Highlight a string according to given line number in JtextArea

Question

Is there any function I can use to actually pass a line number and the string to highlight the word in that line number. I got no clue on how to achieve this.

Am able to load my File on the JtextArea.

The File am loading "Hello.txt" contains:

Hello, This
is my first
lesson in Java
Hope You Have a nice 
Time.

I want the function to highlight string "first" in line 1.

My Codes:

import javax.swing.*;  

import java.util.*;  

import java.io.*;  

public class OpenTextFileIntoJTextArea  
{  
public static void main(String[]args)  
{  
 try  
 {  

  FileReader readTextFile=new FileReader("C:\\Hello.py");  

  Scanner fileReaderScan=new Scanner(readTextFile);  

  String storeAllString="";  

  while(fileReaderScan.hasNextLine())  
  {  
   String temp=fileReaderScan.nextLine()+"\n";  

   storeAllString=storeAllString+temp;  
  }  
  JTextArea textArea=new JTextArea(storeAllString);  
  textArea.setLineWrap(true);  
  textArea.setWrapStyleWord(true);  
  JScrollPane scrollBarForTextArea=new JScrollPane(textArea,JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);  
  JFrame frame=new JFrame("Open text file into JTextArea");  
  frame.add(scrollBarForTextArea);  
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
  frame.setSize(500,500);  
  frame.setLocationRelativeTo(null);  
  frame.setVisible(true);  
 }  
 catch(Exception exception)  
 {  

  System.out.println("Error in file processing");  
 }  
}  
}

See [this](http://stackoverflow.com/questions/13074428/how-can-i-set-each-character-to-a-different-color-background-color-in-a-jtextpan/13076649#13076649) example and its [variation](http://stackoverflow.com/questions/12481698/highlighting-few-of-the-words-of-a-text-file-opened-in-a-frame/12482171#12482171). Also have a read on [Concurrency in Siwng](http://docs.oracle.com/javase/tutorial/uiswing/concurrency/index.html) and dont call `setSize` on `JFrame` use an appropriate `LayoutManager` and/or override `getPreferredSize()` and call `pack()` on `JFrame` before setting it visible. — David Kroukamp, Mar 07 '13 at 17:19

score 2 · Accepted Answer · answered Mar 07 '13 at 17:28

2

Start with methods of JTextArea:

see the getLineStartOffset(...) and getLineEndOffset(...) methods.
then you can use the getText(...) method to get all the text for the line.
then you can use String.indexOf(...) to search the text for the location of "first".
now you can add the offset from the start of the line and the indexOf methods to get the location of the text you want to highlight in the document
then you can use the getHighlighter() method of the text area to get the highlighter
finally you can use the addHighlight() method to highlight the word

answered Mar 07 '13 at 17:28

camickr

321,443
19
166
288

Am new to Java can you show me an example by using codes that you describe in the steps. Thanks – Ms_Joe Mar 07 '13 at 17:32
I would start by creating a method like `highlightText(textArea, row, text)`. Then in the method you try to implement the code one step at a time. – camickr Mar 07 '13 at 17:55

score 0 · Answer 2 · answered Mar 07 '13 at 17:29

0

have you tried playing around with :

JTextComponent.setSelectionStart(int), JTextComponent.setSelectionEnd(int), JTextComponent.setSelectedTextColor(java.awt.Color)

answered Mar 07 '13 at 17:29

Oliver Watkins

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Highlight a string according to given line number in JtextArea

2 Answers2