Extracting a byte array from a JSON

Question

I have a JSON of the following format:

[{"fingerprint":"[79,0,0,0,18,0,0,0,18,0,0,0,19,0,0,0,23,0,0,0,40,0,0,0,42,0,0,0,63,0,0,0,68,0,0,0,71,0,....]"}]

I have been trying to extract the byte array from it using the following:

JSONFingerprint fingerprintData = gson.fromJson(obj, JSONFingerprint.class);

Where JSONFingerprint is:

public class JSONFingerprint {

    byte[] fingerprint;

    public byte[] getfingerprintData() {
        return fingerprint;
    }

}

I have been getting this error:

Exception in thread "Thread-0" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:176)
    at com.google.gson.Gson.fromJson(Gson.java:795)
    at com.google.gson.Gson.fromJson(Gson.java:859)
    at com.google.gson.Gson.fromJson(Gson.java:832)

Does anybody have any ideas??

You've got an array containing an object containing an array. You first need to index the array, then extract element "fingerprint" from the resulting object. The "fingerprint" element will be an array which is presumably the byte array you want. — Hot Licks
– Hot Licks, Commented Mar 26, 2013 at 3:24
But @atw13 has a point that the "fingerprint" element is apparently a String containing the array, so you need to extract the String, then run that through the JSON interpreter to extract the array. — Hot Licks
– Hot Licks, Commented Mar 26, 2013 at 3:25

Rahul · Accepted Answer · 2013-03-26 03:31:52Z

It seems your JSON and POJO don't match. There can be 2 possible solutions for this.

Solution 1:-

If you cannot change the JSON format(i.e.)your JSON is gonna be this,

[{"fingerprint":"[79,0,0,0,18,0,0,0,18,0,0,0,19,0,0,0,23,0,0,0,40,0,0,0,42,0,0,0,63,0,0,0,68,0,0,0,71,0,....]"}]

Then you need to change your JSONFingerprint class to this:-

public class JSONFingerprint {

    String fingerprint;

    public String getfingerprintData() {
        return fingerprint;
    }
}

and you need to parse your JSON like this:-

JSONFingerprint[] dummy = new JSONFingerprint[0]; 
JSONFingerprint[] fingerPrint = gson.fromJson(json, dummy.getClass());
System.out.println(fingerPrint[0].getfingerprintData());

Solution 2:-

If your POJO cannot change(i.e.)your POJO is gonna be this,

public class JSONFingerprint {

    byte[] fingerprint;

    public byte[] getfingerprintData() {
        return fingerprint;
    }
}

Then you'll have to change your JSON format to something like this:-

{"fingerprint":[1,2,3,4,5,6,7,8,9,10]}

which you can parse it usually, as you've already done:-

JSONFingerprint fingerprintData = gson.fromJson(obj, JSONFingerprint.class);

Hope this helps you!

Collectives™ on Stack Overflow

Extracting a byte array from a JSON

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related