How to use Constructor Scanner in java programming to grasp number of lines in text file

Question

I was trying to remove the first line in text file using java code referencing from this link but still the scanner does not contain any text, so it write nothing in the text file, please help, what is then problem...? here is a peace of code,

    File path=new File("C:/Users/kassim Ismail/workspace/Coding/textdoc.txt");
    Scanner scan=new Scanner(path);
    FileWriter newread=new FileWriter("C:\\Users\\kassim Ismail\\workspace\\Coding\\textdoc.txt");
    BufferedWriter newreader=new BufferedWriter(newread);
    while(scan.hasNextLine()){
    String nextline=scan.nextLine();

    if(nextline.equals("\n")){
        newreader.newLine();
    }else{
    newreader.write(nextline);  
    }
    }
    scan.close();
    newreader.close();
    newread.close();
    }

I'm not completely understanding your question However if you would like I can give you sample code to delete the first line of a text file — paul, Oct 22 '16 at 22:25
I was dizy so I wrote poor explanations, but I intended to say "it will be better if you send me other codes to remove the first line of text in a text file". — kassim, Oct 23 '16 at 04:03
Did you tried to execute nextLine() once before the loop (if hasLine is true of course) to skip the first line ? — AxelH, Oct 24 '16 at 12:44

score 0 · Answer 1 · answered Oct 22 '16 at 22:02

0

Right now I don't see any mistake in your code (reader/writer should work). One thing I am unsure about is wether the blank space in your Filepath is problematic or not (Some programs can't work with blank spaces in file paths I am not sure about Java though).

Maybe you could add some System.out.println("") statements for debugging purposes. For Example (testing if the input file exists):

System.out.println("Inputfile exists: "+path.exists())

printing the read line:

System.out.println("Read line: "+nextline)

answered Oct 22 '16 at 22:02

Mein Name

527
3
14

I had already used {system.out.println(nextline) } but it prints nothing, which mean it is empty But before I didn't declare the file I used to declare the path directly into the scanner constructor at that time when {println(nextline)} it was printing the text file path. that it is. – kassim Oct 22 '16 at 22:12
So nextline beeing empty is an error? If so the problem is most likely File path = new File("..."); and the result of path.exists() would be interesting. If that returns 'false' there is most likely a problem with the filepath. – Mein Name Oct 22 '16 at 22:24

score 0 · Answer 2 · answered Oct 24 '16 at 12:41

private boolean removeTopLine(File file){
    try{
        boolean status = false;
        Scanner s = new Scanner(file);
        BufferedWriter writer = new BufferedWriter(new FileWriter(file));
        String content = "";
        int counter = 0;
        while (s.hasNextLine()){
            if (counter > 0){
                content += s.nextLine();
            }
            counter++;
        } 
        writer.write(content);
        writer.close();
        status = true;
    }
    catch (Exception e){
        e.printStackTrace();
    }
    return status;
}

This is a functional code snippet that would delete the first line of a file however there could be debate on efficiency.

How to use Constructor Scanner in java programming to grasp number of lines in text file

2 Answers2