CODEWITHSUNDEEP
java
Rohodude
Rohodude

Reputation: 495

Adding Integers within a list

I am trying to add Integers inside a list together with one line. The problem is that adding Integers in a string return an object itself and not the sum of the Integers.

For example, I have the string 3 4 6 2 7 4.

I want to add all of the numbers together like so: 3 + 4 + 6 + 2 + 7 + 4 = 26. I have tried:

for (String number : after.split ("\\s+")) {
       int v = Integer.parseInt (number);
       System.out.println (v);
       numbers.add (v);
}

Instead of 26, I get [3 4 6 2 7 4]. How do I get the result of the sum of the integers rather than the Object?

Upvotes: 0

Views: 452

Answers (4)

Alexis C.
Alexis C.

Reputation: 93842

Using Java 8 and streams, you'll be able to do this in one line :

int sum = Arrays.stream("1 2 3".split("\\s+")).mapToInt(Integer::parseInt).sum();

Upvotes: 1

takendarkk
takendarkk

Reputation: 3445

How about this

int sum = 0; //Declare a variable to keep track of your sum
for (String number : after.split ("\\s+")) {
    int v = Integer.parseInt (number);
    System.out.println (v);
    numbers.add(v);
    sum += v; //Each iteration of your loop add the current int to your sum
}
System.out.println(sum);

Currently you are just taking each int and adding it to a list. If you want a sum of those values within the list you need another variable to represent this. In my example I have used an int variable named sum. Each time you add an int to your list you will also add it to your current sum value.

Upvotes: 4

Suresh Atta
Suresh Atta

Reputation: 121998

Adding to the List is not the same as adding up integer values. You are looking for

  numbers +=v;

where numbers in an int value and adding up each value v in the loop to it.

int numbers =0;
 for (String number : after.split ("\\s+")) {
                    int v = Integer.parseInt (number);
                    System.out.println (v);
                    numbers +=v;
                }
System.out.println(numbers);

And

numbers +=v; is a shorthand for numbers = numbers+v

Upvotes: 2

Elliott Frisch
Elliott Frisch

Reputation: 201429

I would use a StringTokenizer like so

public static long add(String in) {
    long acc = 0;
    StringTokenizer st = new StringTokenizer(in);
    while (st.hasMoreTokens()) {
        acc += Integer.valueOf(st.nextToken().trim());
    }
    return acc;
}

public static void main(String args[]) throws IOException {
    System.out.println(add("3 4 6 2 7 4"));
}

Which does output 26.

Upvotes: 0

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