java - 同时遍历两个数组

Question

我必须读取一个具有特定数量字段的csv文件。我必须遍历并检测第一列的连续字符串(我使用数组来读取文件)并且仅对于这些字符串，我想获取文件第三列中它们的 int 值的总和，我已将其存储到另一个数组中。到目前为止，我能够检测连续的相同字符串，但是我如何获取它们的值并获取每个字符串的总和？是否可以通过同时遍历来做到这一点？我没有java经验，请帮忙。谢谢。这是我的代码。csv 文件是这样的，带有随机值:

ip, timestamp,elapsed,..
127.0.0.1,...,1500
127.0.0.2,...,2800 
127.0.0.2,...,2400
127.0.0.2,...,2500
127.0.0.3,...,1700
127.0.0.4,...,1600
127.0.0.4,...,1500
127.0.0.5,...,2000

我必须得到这样的东西:127.0.0.2:7700, 127.0.0.4:3100

public static void main(String[] args) {
    try {
        System.out.println("Give file's name: ");
        Scanner in = new Scanner(System.in);
        String filename = in.nextLine();
        File file = new File(filename);
        Scanner inputfile = new Scanner(file);

        String csv_data[];
        ArrayList<String> ip_list = new ArrayList<String>();
        ArrayList<String> elapsed_list = new ArrayList<String>();

        String[] ip_array = new String[ip_list.size()];
        String[] elapsed_array = new String[elapsed_list.size()];

        int i = 0;
        int j = 0;
        int sum = 0;

        while (inputfile.hasNextLine()) {
            String line = inputfile.nextLine();
            csv_data = line.split(",");
            ip_list.add(csv_data[0]);
            elapsed_list.add(csv_data[2]);
        }
        ip_array = ip_list.toArray(ip_array);
        elapsed_array = elapsed_list.toArray(elapsed_array);

        for (String element : elapsed_array) {
            try {
                int num = Integer.parseInt(element);
            } catch (NumberFormatException fe) {
                fe.printStackTrace();
                System.out.println(" That's not a number");
            }
        }
        while (i < ip_array.length) {
            int start = i;
            while (i < ip_array.length && (ip_array[i].equals(ip_array[start]))) {
                i++;
            }
            int count = i - start;
            if (count >= 5) {
                System.out.println(ip_array[start] + " " + "|" + " " + count);
            }
        }
    } catch (FileNotFoundException ex) {
        ex.printStackTrace();
    }
}

Answer 1

public static void main(String[] args) throws Exception {
    List<Data> data = read(getFile());
    Map<String, Integer> idSum = groupByIdWithSum(data);
    // ...
}

private static File getFile() throws Exception {
    try (Scanner scan = new Scanner(System.in)) {
        System.out.println("Give file's name: ");
        return new File(in.nextLine());
    }
}

private static List<Data> read(File file) throws Exception {
    try (Scanner scan = new Scanner(file)) {
        List<Data> res = new ArrayList<>();

        while(scan.hasNextLine()){
            String[] lineParts = scan.nextLine().splie(",");
            res.add(new Data(lineParts[0], Integer.parseInt(lineParts[2])));
        }

        return res;
    }   
}

private static Map<String, Integer> groupByIdWithSum(List<Data> data) {
    Map<String, Integer> map = new HashMap<>();

    for(Data d : data)
        map.put(d.getId(), map.getOrDefault(d.getId(), 0) + d.getElapsed());

    return map;
}

final static class Data {
    private final String ip;
    private final int elapsed;

    public Data(String ip, int elapsed) {
        this.ip = ip;
        this.elapsed = elapsed;
    }

    public String getId() {
        return id;
    }

    public int getElapsed() {
        return elapsed;
    }
}