add values in a array list

Question

I have the following ArrayList

ArrayList<double[]> db_results = new ArrayList<double[]>(); 

Which is populated by the following loop

double[] nums = new double[3];
for ( int i = 0 ; i <= 2; i++) {
    double val = Double.parseDouble(i);
    nums[i] = val;        
}
db_results.add(nums);

How can i add the values from the same position in each array to make another array?? So 1+1+1=3 would be position one of the new array 2+2+2=6 would be position two of the new array and 3+3+3=9 would be position three of the new array??

Cheers

Answer 1

A nested loop would do it.

I would encourage you to take the time to do a Java tutorial or read a textbook. This is really basic stuff, and you'd do better learning the language properly than learning by trial and error interspersed with random SO questions.

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By the way, this line from your code won't compile:

double val = Double.parseDouble(i);

The i variable is declared as an int and the parseXxx methods take a String argument. To convert an int to double, just assign it:

double val = i;

Answer 2

This might be what you're looking for:

double[] newArray = new double[3];
for (double[] array : db_results) {
    for (int i = 0; i < 3; ++i) {
        newArray[i] += array[i];
    }
}

It will work after db_results has been populated. You can also compute the sum array at the same time that db_results is being populated using slukian's method.

Answer 3

Either a java math function or a nested loop its for your answer. Try yourself its just a mathematical calculation.