How can I put multiple values to ArrayList using HashMap?

Question

I received JSON object, and parsed it.

The data is as in the following.

[Parsed_showinfo_2 @ 0x9b4da80] n:88 pts:17425897 pts_time:726.079 pos:149422375 fmt:rgb24 sar:405/404 s:640x360 i:P iskey:1 type:I checksum:48E13810 plane_checksum:[48E13810]
[Parsed_showinfo_2 @ 0x9b4da80] n:89 pts:17471943 pts_time:727.998 pos:149646339 fmt:rgb24 sar:405/404 s:640x360 i:P iskey:0 type:P checksum:1AAD40E0 plane_checksum:[1AAD40E0]
[Parsed_showinfo_2 @ 0x9b4da80] n:90 pts:17503975 pts_time:729.332 pos:149806608 fmt:rgb24 sar:405/404 s:640x360 i:P iskey:1 type:I checksum:3DA5F0DB plane_checksum:[3DA5F0DB]

And then, I did parsing the data using JSONParser(), because I need pts, pts_time values.

FileInputStream fstream = new FileInputStream("myfile");
DataInputStream in = new DataInputStream(fstream);
BufferedReader buff = new BufferedReader(new InputStreamReader(in));

//Which type put to ?
HashMap<String, ?> map = new HashMap<String, ?>();
//Should I use ArrayList too?
//ArrayList<HashMap<String, ?>> list = new ArrayList<HashMap<String, ?>>();

try {
    while (strLine = buff.readLine()) != null) {
        s = strLine.split(" ");
        pts = Long.parseLong(s[4].split(":")[1]);
        ptstime = s[5].split(":")[1];
    }
} catch (IOException ex) { }

I want make multiple array in the while-loop, and return result value.

Like this:

["pts": {1, 2, 3, 4, 5}, "ptstime": {10.11, 13.003, 15.12, 16.53, 18.10}]

The pts and ptstime are the keys.

How can I coding in the while-loop

Where is the JSON object? Where do you call the JSON parser? What are you reading from the file? And why via DataInputStream? — Thilo
– Thilo, Commented May 12, 2016 at 10:17
you can just add the values into the hash map after the loop, — KP.
– KP., Commented May 12, 2016 at 10:18

Nicolas Filotto · Accepted Answer · 2016-05-12 10:29:49Z

1

Here is how you can do it:

Map<String, List<Object>> map = new HashMap<>();
...
while (strLine = buff.readLine()) != null) {
    s = strLine.split(" ");
    pts = Long.parseLong(s[4].split(":")[1]);
    List<String> listPts = map.get("pts");
    if (listPts == null) {
        listPts = new ArrayList<>();
        map.put("pts", listPts);
    }
    listPts.add(pts);
    // Here apply the same logic to the rest
}

But a better approach could be to use a List of Map instead, like this:

List<Map<String, Object>> list = new ArrayList<>();
while (strLine = buff.readLine()) != null) {
    s = strLine.split(" ");
    Map<String, String> map = new HashMap<>();
    list.add(map);
    pts = Long.parseLong(s[4].split(":")[1]);
    map.put("pts", pts);
    // Here apply the same logic to the rest
}

answered May 12, 2016 at 10:29

Nicolas Filotto

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Vampire · Accepted Answer · 2016-05-12 10:32:27Z

1

What is the DataInputStream for as you use it just as argument for the InputStreamReader, the FileInputStream should be fine already.

As to your question, I guess what you want is

Map<String, List<?>> map = new HashMap<>(2);
map.put("pts", new ArrayList<Long>());
map.put("ptstime", new ArrayList<Long>());

And then in the while loop something like

map.get("pts").add(pts.toString());
map.get("ptstime").add(ptstime);

answered May 12, 2016 at 10:32

Vampire

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