Java adds text to a specific line in a file

I wonder if I can add a line to a file with Java

For example, myfile:

1: line 1
2: line 2
3: line 3
4: line 4

I want to add a line fox example on the third line, so it looks like this

1: line 1
2: line 2
3: new line
4: line 3
5: line 4

I've found how to add text to an empty file or at the end of a file, but I don't know how to execute it in the middle of the text without deleting lines

Another way is to divide the first file into two parts, then create a file, add the first part to the new part, and then add the second part, because it feels a little extreme?

thank you

Solution

In Java 7, you can use the files and path classes as follows:

List<String> lines = Files.readAllLines(path,StandardCharsets.UTF_8);
lines.add(position,extraLine);
Files.write(path,lines,StandardCharsets.UTF_8);

for instance:

Path path = Paths.get("C:\\Users\\foo\\Downloads\\test.txt");
List<String> lines = Files.readAllLines(path,StandardCharsets.UTF_8);

int position = lines.size() / 2;
String extraLine = "This is an extraline";  

lines.add(position,StandardCharsets.UTF_8);