Java Scanner Array

Question

I am having troubles with java. I need to scan numbers (example: 1 3 4 2 5 6 7) and put them into array. The problem is I don't know how long it will be. Is there a command that I can use to determine the length of the numbers putted in scanner?

Answer 1

If you don't want to use ArrayList, as a workaround, I advice to read the entire line and then split to get the length and individual values:

   String line = scanner.nextLine();
   String[] values = line.split(" ");
   int[] intValues = new int[values.length];
   int indx = 0;
   for(String value:values){
     intValues[indx++] = Integer.parseInt(value);
   }

EDIT: Second approach:

   List<Integer> numList = new ArrayList<Integer>();
   int number = 0;
   while (number != -1) {
      System.out.println("Enter a positive integer value (or -1 to stop): ");
      number = Integer.parseInt(in.nextLine());
      if (number != -1){
        numList.add(number);
      }
   }
   in.close();

   Integer[] numArray = numList.toArray(new Integer[numList.size()]);

EDIT2: Taking care of multiple numbers in the same line and terminating at empty line

List<Integer> numList = new ArrayList<Integer>();
while(true) {
   System.out.println("Enter a positive integer value (or -1 to stop): ");
   String line = in.nextLine();
   if(line.length() <1){
      break;
   }
   String [] numbers = line.split(" ");
   for(String num: numbers){
          numList.add(Integer.parseInt(num));
   }
 }
 in.close();

 Integer[] numArray = numList.toArray(new Integer[numList.size()]);

Answer 2

Use an ArrayList if you want a variable-size collection.

ArrayList<Integer> lst = new ArrayList<Integer>();
lst.add(scanner.getInt());