CODEWITHSUNDEEP
javajava.util.scannerbufferedreaderfilereader
lo1gur
lo1gur

Reputation: 160

Scanner Java just reading the first line

I have a text file like so:

1 2
3 7
5 8

with 2 numbers on each row. I want to do something different with the first number and the second number. I'm trying to scan through the text file and print the numbers to make sure that I scanned it right. However, only the first two numbers show up (1 4), then an error says: 

"java.util.NoSuchElementException
    at java.base/java.util.Scanner.throwFor(Scanner.java:858)
    at java.base/java.util.Scanner.next(Scanner.java:1497)
    at java.base/java.util.Scanner.nextInt(Scanner.java:2161)
    at java.base/java.util.Scanner.nextInt(Scanner.java:2115)
    at com.company.SCC.input(SCC.java:30)
    at com.company.SCC.<init>(SCC.java:15)
    at com.company.Main.main(Main.java:11)"

I don't understand what the problem is and how to scan the document row by row (I recycled the code for the Scanner and it was previously working). I'm not sure what I'm doing wrong, any help would be appreciated. 

try {
        String file = "testcase1.txt";
        FileReader in = new FileReader(file);
        BufferedReader br = new BufferedReader(in);
        String s;
        int x;
        while ((s = br.readLine()) != null) {
            Scanner sca = new Scanner(s);
            x = sca.nextInt();
            graph.addVertex(x);
            int y = sca.nextInt();
            graph.addAdjvex(x, y);
            System.out.println(x + " " + y);
        }

    } catch (Exception e) {
        e.printStackTrace();
    }

Upvotes: 1

Views: 3560

Answers (3)

Duke
Duke

Reputation: 416

Try 

try {
    File file = new File("testcase1.txt");
    Scanner sc = new Scanner(file);
    int x, y;
    while (sc.hasNextLine()) {
        x = sc.nextInt();
        y = sc.nextInt()
        graph.addVertex(x);
        graph.addAdjvex(x, y);
        System.out.println(x + " " + y);
    }
    sc.close();
} catch (Exception e) {
    e.printStackTrace();
}

Upvotes: 1

John
John

Reputation: 33

maybe you should call sc.nextLine () to jump to the next line

Upvotes: 0

Fermat&#39;s Little Student
Fermat&#39;s Little Student

Reputation: 6309

try {
    File file = new File("testcase1.txt");
    Scanner sc = new Scanner(file);
    while (sc.hasNextLine()) {
        int x = sc.nextInt();
        int y = sc.nextInt();
        sc.nextLine();
        graph.addVertex(x);
        graph.addAdjvex(x, y);
        System.out.println(x + " " + y);
    }
    sc.close()

} catch (Exception e) {
    e.printStackTrace();
}

Upvotes: 1

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