reading input delimited by spaces in java

Question

im struggling with the below question.

Question: Input contains the number of blocks n (1 ≤ n ≤ 20) and weights of the blocks w1, …, wn (integers, 1 ≤ wi ≤ 100000) delimited by white spaces. the input should be taken from the user.

1. how should i write the input with spaces? (lets say my input for no. of blocks is n =5 and the weights of the blocks be : 2 3 55 6 33 - because n=5)
2. how should i read the input which are given with white spaces and store it in some list or array ? using what commands.

please find my code:

public static void main(String[] args) {
    int b1 = 0;
    Scanner in = new Scanner(System.in);
    System.out.println("Enter no. of blocks: ");
    b1 = in.nextInt();
    if (b1<=20) {
        in.nextLine();
        int[] arr = new int[b1];
        for (int i=0; i<b1; i++) {
            System.out.println("Enter a weights of ths blocks: ");
            if (arr[i]<=100000) {
          arr[i] = in.nextInt();




            }
    }
        }

i dont think this is the right way coz the input should be delimited with spaces..

i was thinking about the ways to proceed but couldnt come up with any solution. can u please help me our on this guys. thanks.

Answer 1

1. The input can be given at command line as "input1 input2 input3" (Weights separated by spaces)

2. You can use Scanner to read the input. Consider the sample code below:

Assuming the input is only integers.

 Scanner scanner = new Scanner(System.in);
 int numOfBlocks = scanner.nextInt();
 int weightArray[] = new weightArray[numOfBlocks];
 for(int i=0;i<numOfBlocks;i++)
       {
        weightArray[i] = scanner.nextInt();
       }
 scanner.close();
//your logic

Answer 2

There's a very easy way to read input delineated by spaces: use string.split(delimit):

String input = "this is a test";
String[] tokens = input.split(" ");

That'll give you an array, tokens, of "this", "is", "a", and "test".

Then you can convert to an int array like this:

int[] inputNumbers = new int[tokens.length];
for(int i = 0; i < tokens.length; i++) {
    inputNumbers[i] = Integer.parseInt(tokens[i]);
}

Just make sure that you are sure that you have numbers as an input.