Java Equivalent to fscanf in C

Question

Hi I i'm trying to do a line by line reading in of a file in Java. For example I'd like to be able to do something like

//c code
while( fscanf(ptr, "%s %s %s",string1,string2,string3) == 3)
     printf("%s %s %s",string1,string2,string3);

Where I scan in every line in the file individually and store it in a variable.

I have started out by making a file object and finding the file. However I haven't found a function to be able to read input.

[Just a starting point](https://stackoverflow.com/questions/2231369/scanner-vs-bufferedreader) — user3386109, Oct 21 '18 at 01:31

score 3 · Answer 1 · answered Oct 21 '18 at 01:32

3

Use line oriented input, split the lines and print the contents. That is, read each line, check if you have three tokens (end if you don't) and print them. Like,

Scanner sc = new Scanner(System.in);
while (sc.hasNextLine()) {
    String line = sc.nextLine();
    String[] tokens = line.split(" ");
    if (tokens.length != 3) {
        break;
    }
    System.out.printf("%s %s %s%n", tokens[0], tokens[1], tokens[2]);
}

Change System.in to a File to read from a file.

answered Oct 21 '18 at 01:32

Elliott Frisch

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Hi, what would I type where you wrote System.in? For example the file would be called file.txt – User9123 Oct 21 '18 at 01:57
@User9123 `new File("file.txt")` - note that you are responsible for PATHing. So I would normally prefer something like `new File(System.getProperty("user.home"), "file.txt")` – Elliott Frisch Oct 21 '18 at 02:01
for some reason, it is printing file.txt instead of of the lines in the file if I do the code up until the part with the tokens, any ideas why? – User9123 Oct 21 '18 at 02:35
Yes. You forgot `new File`. – Elliott Frisch Oct 21 '18 at 02:36
I see I have changed my scanner to a file, however now my nextLine() is not working – User9123 Oct 21 '18 at 02:39
nevermind i fixed it with a try catch – User9123 Oct 21 '18 at 02:45

Java Equivalent to fscanf in C

1 Answers1