java - Inserting text in middle using RandomAccessFile removes some text after that

Question

My Sample Code

    String line = null;
    RandomAccessFile file = new RandomAccessFile("D:/mahtew.txt", "rw");
    System.out.println(file.getFilePointer());
    while((line = file.readLine()) != null){
        System.out.println(line);
        System.out.println(file.getFilePointer());

        if(line.contains("Text to be appended with")){
            file.seek(file.getFilePointer());
            file.write(" new text has been appended".getBytes());
            break;
        }
    }
    file.close();

demo.txt before execution

one two three
Text to be appended with
five six seven
eight nine ten

demo.txt after execution

one two three
Text to be appended with
 new text has been appendedten

Also i tried using setLength to change length of file before new text is appended. But still some text is getting trimmed from output file. Any help will be appreciated

Thanks Mathew

Answer 1

RandomAccessFile

A random access file behaves like a large array of bytes stored in the file system.

In fact it does not care about shifting the array elements in the case of write operations (only the pointer is advanced). Such an operation overwrites existing values:

Output operations write bytes starting at the file pointer and advance the file pointer past the bytes written.