io - How can I remove last 2 lines in text file in Java?

Question

I want remove last 2 lines in my text file using java. I tried 4 or 5 different ways about this, but I can't find working code. I will edit file like this:

[
    {
        "example"
    }
]

I want delete "]" , "}" and add "example2". How can I do that ? (I'm using SE 1.8 , maybe version have an effect on this)

Can you recommend anything ?

Thanks.

Answer 1

You could try reading the file, then writing it all over again but without the last 2 lines:

public void removeLastLines() {
    int lines = 2; //This is the number that determines how many we remove
    try(BufferedReader br = new BufferedReader(new FileReader(file))){
        List<String> lineStorage = new ArrayList<>();
        String line;
        while((line=br.readLine()) !=null) {
            lineStorage.add(line);
        }
        try(BufferedWriter bw = new BufferedWriter(new FileWriter(file))){
            int lines1 = lineStorage.size()-lines;
            for(int i = 0; i < lines1; i++) {
                bw.write(lineStorage.get(i));
                bw.newLine();
            }
        }
    }catch(Exception e) {
        e.printStackTrace();
    }
}