CODEWITHSUNDEEP
java
momodjib
momodjib

Reputation: 193

Java - Treat data from a file

I have a file that looks like this:

year        population
1952        120323
1953        136688
1954        161681
....        .....

I want to go in that find the year with the largest increase in population as compared to the previous year.

I tried th following code but I get a the NoSuchElementException and I'm not sure why:

    String path = "filePath";
    File file = new File(filePath);
    Scanner sc = new Scanner(file);
    int y = 0, y1, y2, p1, p2, diff = 0;
    while(sc.hasNext()){
        if(sc.next().equals("year") || sc.next().equals("population")){
            break;
        }else{
            y1 = Integer.parseInt(sc.next());
            p1 = Integer.parseInt(sc.next());
            y2 = Integer.parseInt(sc.next()); // this line throws the exception
            p2 = Integer.parseInt(sc.next());
            if(p2 - p1 > diff){
                diff = y2-y1;
                y = y2;
            }
        }
    }
    System.out.println(y);

Upvotes: 0

Views: 83

Answers (2)

Siva
Siva

Reputation: 176

Not sure how your code produced NoSuchElementException error. Because you are exiting from the loop when you find "year" or "population". Hope the following code should meet your expected result.

    String path = "filePath";
    File file = new File (path);
    Scanner scanner = new Scanner(file);
    Long[][] yd = new Long[0][];
    long prev = 0;
    for(scanner.nextLine();scanner.hasNext();){
        long year = scanner.nextLong();
        long curnt = scanner.nextLong();
        long diff = prev==0?prev:curnt-prev;
        prev = curnt;
        yd = Arrays.copyOf(yd, yd.length+1);
        yd[yd.length-1] = new Long[2];
        yd[yd.length-1][0] = year;
        yd[yd.length-1][1] = diff;
    }
    Arrays.sort(yd, new Comparator<Long[]>() {
        @Override
        public int compare(Long[] o1, Long[] o2) {
            Long diffOne = o1[1];
            Long diffTwo = o2[1];
            return diffTwo.compareTo(diffOne);
        }
    });
    System.out.println("Year="+yd[0][0]+"; Difference="+yd[0][1]);

Upvotes: 1

Kwame Opare Asiedu
Kwame Opare Asiedu

Reputation: 2355

Try this...

String path = "filePath";
File file = new File (filePath);
Scanner sc = new Scanner(file);
long year = 0L, population = 0L, largestDiff = 0L;

while (sc.hasNext()) {
    String line = sc.nextLine();

    if (line.startsWith("year")) {
        continue;
    } else {
        String[] parts = line.split(" +"); // Note the space before "+"
        long currentYear = Long.parseLong(parts[0]);
        long currentPopulation = Long.parseLong(parts[1]);
        long diff = currentPopulation - population;

        if (dif > largestDiff) {
            largestDiff = diff;
            year = currentYear;
        }

        population = currentPopulation;
    }
}

System.out.println(year);
System.out.println(largestDiff);

Upvotes: 1

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