Reading Inputs in Java - help

Question

I am having a problem reading inputs, can anyone help me.

Each line of the input have to Integers: X e Y separated by a space.

12 1    
12 3  
23 4  
9 3 

I am using this code in java but is not working, its only reading the first line can anyone help me?

    String []f; 
    String line;
    Scanner in=new Scanner(System.in);

    while((line=in.nextLine())!=null){
        f=line.split(" ");

        int X,Y;
        X=Integer.parseInt(f[0]);
        Y=Integer.parseInt(f[1]);

        if(X<=40 && Y<=40)
          metohod(X,Y); 


        line=in.nextLine();

    }
}

Answer 1

You are calling nextLine twice, once in the while, anotherone linha = xxx; what is linha anyways? Try this

BufferedReader reader = new BufferedReader(...);
while((line = reader.readLine())!=null) {
  String[] f = line.split(" ");
  int X,Y;
  X=Integer.parseInt(f[0]);
  Y=Integer.parseInt(f[1]);
}

Answer 2

line=in.nextLine();

You are reading the next line and doing nothing with it. If you remove that it should work.

Answer 3

You're calling one line=in.nextLine() too much, but why not use in.nextInt()? The following should work as expectd:

Scanner in = new Scanner(System.in);

while(in.hasNextLine()) {
    int x = in.nextInt();
    int y = in.nextInt();

    if(x <= 40 && y <= 40)
        method(x, y); 
}

(The code is tested, and it reads more than just the first line. Your previous problem could perhaps be the new-line format of the input file.)

Have a look at the scanner API docs.

---

To debug this you could use the Scanner(File file) constructor instead.

Answer 4

Since you are using Scanner, why don't you just use nextInt() instead of nextLine()? That way you could call nextInt() twice and get the two numbers for each line.

The way you coded it looks as if you are trying to use a BufferedReader instead of a Scanner.