int arrays to json object in java

Question

I'm trying to put two int [] and a double [] in JSON format to send through my java servlet. This is what I have so far.

private JSONObject doStuff(double[] val, int[] col_idx, int[] row_ptr){
    String a = JSONValue.toJSONString(val);
    String b = JSONValue.toJSONString(col_idx);
    String c = JSONValue.toJSONString(row_ptr);
    JSONObject jo = new JSONObject();
    jo.put("val",a)
    jo.put("col",b);
    jo.put("row",c);
    return jo;
}

But when I print the JSONobject, I get this unreadable result:

{"val":"[D@62ce3190","col":"[I@4f18179d","row":"[I@36b66cfc"}

I get the same result in javascript where I am sending the JSONObject to. Is there a problem with the conversion from numbers to string? Should I perhaps use JSONArray instead?

If you try printing val on the console, it will print the same thing. It is the address of val array and similarly for the others. — user007
– user007, Commented Oct 29, 2015 at 12:33
Indeed. String a = Arrays.toString(val) did the trick though. — kongshem
– kongshem, Commented Oct 29, 2015 at 12:37
You need to first convert your arrays into readable format(convert it into list using Arrays.asList()), and then process it. — Vivek Singh
– Vivek Singh, Commented Oct 29, 2015 at 12:38

Community · Accepted Answer · 2017-05-23 12:23:39Z

7

It is because the toString method of int[] or double[] is returning the Object's default Object.toString().

Replace with Arrays.toString(int[]/double[]), you will get expected result.

Check this answer for more explantion about toString.

edited May 23, 2017 at 12:23

CommunityBot

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answered Oct 29, 2015 at 12:38

rajuGT

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1 Comment

kongshem Over a year ago

I figured it out riiight before your answer, but thanks. Will mark this as the correct answer after the "you can accept an answer in 3 minutes" prompt.

Shivam · Accepted Answer · 2015-10-29 12:40:29Z

0

Instead of using

jo.put("val",a)
jo.put("col",b);
jo.put("row",c);

Use;

jo.put("val",val);
jo.put("col",col_idx);
jo.put("row",row_ptr);

answered Oct 29, 2015 at 12:40

Shivam

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