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Index › Programming Questions & Help › Syntax Questions › Append to an Existing Line in text file
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Append to an Existing Line in text file (Read 957 times)
leBatonTotem
Append to an Existing Line in text file
May 11th, 2009, 8:43am  
Hello,
I am trying to append data to existing lines in a text file, I need to specify which line to write too, but I don't see this information in the reference.

For example if the text file looks like this:

line1:
line2:

I would like to be able to write specific data to each line, something like:

writer.appendLines(1, "this is line 1");
writer.appendLines(2, "this is line 2");

text:
line1: this is line 1
line2: this is line 2


Thanks in advance for any help
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PhiLho 
Re: Append to an Existing Line in text file
Reply #1 - May 11th, 2009, 9:11am  
At least two ways to do it:
- If file isn't very big, just read it into an array of lines, append what you need, and write back the file;
- If the file is really big, read it line per line, writing them to another file, and when reaching the target lines, modify them before writing them.
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action_owl
Re: Append to an Existing Line in text file
Reply #2 - May 11th, 2009, 1:34pm  
Code:

BufferedWriter writer;

writer = new BufferedWriter(new FileWriter("filename", true));
writer.write("yourString\r\n");
writer.close();


That will append to the end of a file but if you want to be able to use something like:

"writer.appendLines(1, "this is line 1");"

you would have to write a library/class for that purpose using the method PhiLho described.
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