CODEWITHSUNDEEP
java
white_tree
white_tree

Reputation: 1067

Inserting scanner input directly into arraylist

I wanted to extract input from my scanner and insert it directly into a typesafe arraylist. Here is my code:

public static void main(String args[])
{
    List<Integer> arglist=new ArrayList<Integer>();
    List<Integer> resultlist=new ArrayList<Integer>();
    Scanner in=new Scanner(System.in);
    System.out.println("Scanning");
    while(in.hasNext())
    {
        arglist.add(in.nextInt());
    }
    System.out.println("Scan complete, sorting...");
    System.out.println(arglist);
    resultlist=qksort(arglist);
    System.out.println(resultlist);

}

This works only when I explicitly terminate input using Ctrl+Z. Shouldn't the stream terminate when I press "Enter"?

Upvotes: 0

Views: 551

Answers (2)

sprinter
sprinter

Reputation: 27986

No it won't terminate when you press the enter key. The scanner will read that as a newline character and interpret it as a delimiter between tokens and happily continue.

A very simple solution if you want to continue processing is:

while (in.hasNextInt()) {
    argList.add(in.nextInt());
}

That way the first time you type something that isn't a number or whitespace (e.g. "exit") it will continue.

If you particularly want to just input a single line then you can use the scanner to read a line and then scan that line:

Scanner scanner = new Scanner(System.in);
scanner = new Scanner(scanner.nextLine());

Upvotes: 1

Manoj
Manoj

Reputation: 76

If End of Stream didn't appear as in case of Files or 'Ctrl + Z' in case of standard input, then hasNext() method is blocking...it means-
Either it finds pattern in buffer: in this case it return True.
Or if it goes for reading from underline stream: in this case it might block.

Upvotes: 0

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