How to read multiple integer values from one line in Java using BufferedReader object?

Question

I am using BufferedReader class to read inputs in my Java program. I want to read inputs from a user who can enter multiple integer data in single line with space. I want to rea

Answer 1

Late to the party but you can do this in one liner in Java 8 using streams.

InputStreamReader isr= new InputStreamReader();
BufferedReader br= new BufferedReader(isr);

int[] input = Arrays.stream(br.readLine().split("\\s+")).mapToInt(Integer::parseInt).toArray();

Answer 2

I use this code for List:

List<Integer> numbers = Stream.of(reader.readLine().split("\\s+")).map(Integer::valueOf).collect(Collectors.toList());

And it is almost the same for array:

int[] numbersArray = Arrays.stream(reader.readLine().split("\\s+")).mapToInt(Integer::valueOf).toArray(); 

Answer 3

Integer.parseInt(br.readLine()) -> Reads a whole line and then converts it to Integers.

scanner.nextInt() -> Reads every single token one by one within a single line then tries to convert it to integer.

String[] in = br.readLine().trim().split("\\s+"); 
// above code reads the whole line, trims the extra spaces 
// before or after each element until one space left, 
// splits each token according to the space and store each token as an element of the string array.


for(int i = 0; i < n; i++)
    arr[i] = Integer.parseInt(in[i]);

// Converts each element in the string array as an integer and stores it in an integer array.

Answer 4

Well as you mentioned there are two lines- First line takes number of integers and second takes that many number

INPUT: 5 2 456 43 21 12

So to address this and covert it into array -

String[] strs = inputData.trim().split("\\s+");  //String with all inputs 5 2 456 43 21 12

int n= Integer.parseInt(strs[0]);    //As you said first string contains the length

int a[] = new int[n];               //Initializing array of that length

for (int i = 0; i < n; i++)         
{

a[i] = Integer.parseInt(strs[i+1]);     // a[0] will be equal to a[1] and so on....

}


     
        

Answer 5

If you want to read integers and you didn't know number of integers

String[] integersInString = br.readLine().split(" ");
int a[] = new int[integersInString.length];
for (int i = 0; i < integersInString.length; i++) {
    a[i] = Integer.parseInt(integersInString[i]);
}

Answer 6

Try the next:

int a[] = new int[n];
String line = br.readLine(); // to read multiple integers line
String[] strs = line.trim().split("\\s+");
for (int i = 0; i < n; i++) {
    a[i] = Integer.parseInt(strs[i]);
}