CODEWITHSUNDEEP
javajava.util.scanner
Daniel Švarc
Daniel Švarc

Reputation: 69

How to force Scanner to read unfinished line

I have a problem with last line of input. I cannot force Scanner to read a number from last line since it is unfinished. When I copy input with one more line after the previous last line, there is no problem, but i cannot have the extra line there.

Link to problem

Example of input: 

2  
1 1  
9 9  
4   
4 5  
6 5  
2 5  
3 4  

-1

I've tried sc.nextInt(), sc.next(), sc.nextLine() and nothing can reach the -1. Even sc.hasNext, sc.hasNextInt etc. are waiting.

while(true)
    {
        line = sc.nextLine();
        try {
            a = Integer.parseInt(line);
        } 
        catch (NumberFormatException e) {
        }

        if(a == -1)
        {
            break;
        }

        rr = new int[a][2];

        for(int i = 0; i < a; i++)
        {
            line = sc.nextLine();
            numbers = line.split(" ");

            try {
                rr[i][0] = Integer.parseInt(numbers[0]);
                rr[i][1] = Integer.parseInt(numbers[1]);
            } 
            catch (NumberFormatException e) {
            }

        }

        b = sc.nextInt();

        sc.nextLine();

        tt = new int[b][2];

        for(int i = 0; i < b; i++)
        {
            line = sc.nextLine();
            numbers = line.split(" ");

            try {
                tt[i][0] = Integer.parseInt(numbers[0]);
                tt[i][1] = Integer.parseInt(numbers[1]);
            } 
            catch (NumberFormatException e) {
            }

        }
        sc.nextLine();

    }

Upvotes: 0

Views: 146

Answers (2)

denvercoder9
denvercoder9

Reputation: 3021

while(true) {
    // read the line.. 
    line = sc.nextLine().trim();
    // check if it's a blank line...
    // blank line means new test case.. Take the value of n
    if (line.length() == 0) line = sc.nextLine().trim();

    // now parse the value of n.. If it's -1 then end of input
    a = Integer.parseInt(line);
    if (a==-1) break;

    // rest of your input
}

Take the value of b like this:

b = Integer.parseInt(sc.nextLine().trim());

And remove the 'extra' sc.nextLine()from below of b and from the bottom of while loop. That case is handled at the top.

Upvotes: 1

Dane Williams
Dane Williams

Reputation: 82

Before trying to get the -1 you could have a separate scanner use the delimiter /n (line break) and have it delete the extra break between -1 and the last line before it. Then you could go through and just scan with .nextLine() or .nextInt().

Upvotes: 0

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