How to read every Integers in a line from a file in Java?

Question

I have file that has n lines of Integers. I want to add each int in each line and print them (so I should print 3 int at the end, each one for a line).

I tried this but it will read and add all the Integers in the first loop.

scan = new Scanner(new BufferedReader(new FileReader("input.txt")));
int n = scan.nextInt();
for (int i = 0; i < n; i++) {
    while (scan.hasNextLine()) {
         sum += scan.nextInt();
    }
    System.out.println(sum);
    sum = 0;
}

Answer 1

This behavior is caused by erroneous usage of loops and scans. One of correct solutions also incorporates java 8 lambdas, with the assumption that the delimiter of the integers in the file is space(" "):

    Path path = Paths.get("your path");
    try{
        Files.lines(path)
                .map( line -> line.split(" "))
                .mapToInt( numbers -> Arrays.stream(numbers)
                   .reduce(0 , (sum, num) -> sum + Integer.parseInt(num), (first, second) -> first + second ))
                .forEachOrdered(System.out::println);

    } catch (IOException e){
        e.printStackTrace();
    }

Answer 2

I think I could do this too...

read = new Scanner(new BufferedReader(new FileReader("input.txt")));
int n = read.nextInt(), j;
int sum = 0;
for (int i = 0; i < n; i++) 
{
    String[] str;
    int t = read.nextInt();
    // First str will be ""(it reads the end of each line) 
    str = read.nextLine().split(" ");
    // Then it can read what we want
    str = read.nextLine().split(" ");
    for (j = 0; j < str.length; j++) 
    {
        sum += Integer.parseInt(str[j]);
    }
    System.out.println(sum);
    sum = 0;                
}