Java-处理文件中的数据

Posted 2021-04-01

我有一个看起来像这样的文件：

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

我想找到那个人口比上一年增加最多的年份。

我尝试了以下代码，但得到了NoSuchElementException，但不确定为什么：

    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);

答案

尝试一下...

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);