Question

I have two ArrayLists in java that have different sizes. ArrayLists ‘probs’ and ‘theDoubles’ (sizes 4 and 5 respectively). Array ‘dprobs’ (Double[5]) is just an Array that copies the values of ‘theDoubles’.

Only those items that do not have zero-length (see ‘.size() > 0’) are allowed to be added. One of them is zero-length, and gets replaced by a ‘0.0’ double (added to the ‘theDoubles’ ArrayList).

My problem is that I do not know how to get this desired output:

i=1 j=0
i=2 j=1
i=3 j=2
i=4 j=3
    j=4

I get this instead:

i=1 j=1
i=2 j=2
i=3 j=3
i=4 j=4

Here is my code:

        for (int i = 0; i < 5; i++) {
            if (probs.get(i).size() > 0) {
                System.out.println("i: " + i);
                System.out.println("j: " + j);

                theDoubles.add(Double.parseDouble(probs.get(i).get(0).getValue()));
                dprobs[j] = theDoubles.get(j);
            } else {
                theDoubles.add(0.0);
            }
            j++;
        }
        return dprobs;

I need to display this (‘probs’ ArrayList contents):

0.0
0.0049522
0.0020487
0.0013568
0.0015332

and I am only getting this:

0.0049522
0.0020487
0.0013568
0.0015332

because ‘j’ starts at ‘1’ (it ignores the first item, which is ‘0.0’ at index 0).

Any ideas?

Thanks

Answer 1

It is hard to see the full picture because nothing shows where you print the second set of outputs and desired outputs. therefore i will try based on the first set that you posted: you need to increase j only when you are at an i which points to an element that is not zero length. therefore, move the j++ to your “if” block too. it becomes like this:

for (int i = 0; i < 5; i++) {
        if (probs.get(i).size() > 0) {
            System.out.println("i: " + i);
            System.out.println("j: " + j);

            theDoubles.add(Double.parseDouble(probs.get(i).get(0).getValue()));
            dprobs[j] = theDoubles.get(j);
            j++;
        } else {
            theDoubles.add(0.0);
        }

    }
    return dprobs;