Trying to create loop that fills array using info from another array + hash map

Question

I'm trying to prepare data to be used inside of a histogram. I want 2 arrays, one is all the temperatures from my highest and lowest collected temperature. The second array will contain the frequency of each temperature.

int difference is the difference from the lowest and highest temp

Array temp contains the temperatures collected

HashMap map contains the frequencies collected of each temp

Array tempGaps contains the temperatures + every other temp that was not collected

Array finalTemps contains the frequency of each temp.

The goal I hope to achieve is two arrays, one with all the temperatures, one with the frequencies of each and their index value is what corresponds them to eachother.

public void fillGaps() {
    int j = 0;
    tempGaps = new int[difference];
    finalTemps = new int[difference];
    for (int i = 0; i < difference; i++) {
        tempGaps[i] = temp[0] + i;
        if (tempGaps[i] == temp[j]) {
            finalTemps[i] = map.get(new Integer(tempGaps[i]));
            j++;
        } else {
            finalTemps[i] = 0;
        }
    }
}output: https://pastebin.com/nFCZXFyp

Output:

7 ->1 9 ->1 10 ->1 12 ->1 14 ->2 15 ->1 16 ->1 18 ->2 19 ->1 21 ->1 
TEMP GAPS
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 
FINAL TEMPS
1 0 1 1 0 1 0 2 0 0 0 0 0 0 0

My finalTemp output stops after 14 degrees - occurs 2 times. It does this after any data set I put in which has a frequency of more than 1. Please help! Thanks!!

Answer 1

I don't believe you need the j variable. It seems to make things confusing, especially because the for loop is only a single pass-through. Instead, fetch the value from the map. If null, assign 0, otherwise, assign the value.

public void fillGaps() {       
    tempGaps = new int[difference];
    finalTemps = new int[difference];
    for (int i = 0; i < difference; i++) { //navigate through every temperature
        tempGaps[i] = temp[0] + i; //assign the current temperature
        Integer frequency = map.get(new Integer(tempGaps[i])); //fetch the frequency
        finalTemps[i] = frequency == null ? 0 : frequency; //assign 0 if null, otherwise frequency if not null
    }
}