How do I parse Json data with Gson when not everything is labelled

I have happily been using Google Gson to parse extract some JSON metadata of the form

Gson


"lowlevel":
"average_loudness": 0.570070445538
,
"rhythm":
"beats_count": 502,
"bpm": 128.347702026
,
"tonal":
"chords_changes_rate": 0.0534749031067
"tuning_diatonic_strength": 0.431238204241,
"tuning_equal_tempered_deviation": 0.164615109563,
"tuning_frequency": 434.193115234,
"tuning_nontempered_energy_ratio": 0.847496032715




Using this

public class AcousticBrainzLowlevelWrapper

private AcousticBrainzLowLevelRhythm rhythm;
private AcousticBrainzLowLevelTonal tonal;

public AcousticBrainzLowLevelRhythm getRhythm()

return rhythm;


public void setRhythm(AcousticBrainzLowLevelRhythm rhythm)

this.rhythm = rhythm;


public AcousticBrainzLowLevelTonal getTonal()

return tonal;


public void setTonal(AcousticBrainzLowLevelTonal tonal)

this.tonal = tonal;




and

AcousticBrainzLowlevelWrapper low = gson.fromJson(result, AcousticBrainzLowlevelWrapper.class) ;


(Full JSON can be seen here)

but now the API has been extended to allow multiple lookups such as this url

which now returns

{
"96685213-a25c-4678-9a13-abd9ec81cf35": {
"0":
"lowlevel":
"average_loudness": 0.570070445538
,
"rhythm":
"beats_count": 502,
"bpm": 128.347702026
,
"tonal":
"chords_changes_rate": 0.0534749031067
"tuning_diatonic_strength": 0.431238204241,
"tuning_equal_tempered_deviation": 0.164615109563,
"tuning_frequency": 434.193115234,
"tuning_nontempered_energy_ratio": 0.847496032715


.....
"78787888-a25c-4678-9a13-abd9ec81cf35": {
"0": {
"lowlevel": {
......
..


The difference being that the json doesn't define what "96685213-a25c-4678-9a13-abd9ec81cf35" and "78787888-a25c-4678-9a13-abd9ec81cf35" are, or what "0" is.

So I know what they represent (MusicBrainzRecording and offset) but I cannot create a class like AcousticBrainzLowlevelWrapper to represent this, so how do I parse this new api.

AcousticBrainzLowlevelWrapper

Update
I tried creating

public class AcousticBrainzLowLevelList

private Map<String, AcousticBrainzLowlevelWrapper> data = new HashMap<>();

public Map<String, AcousticBrainzLowlevelWrapper> getData()

return data;


public void setData(Map<String, AcousticBrainzLowlevelWrapper> data)

this.data = data;




and then calling

AcousticBrainzLowLevelList lowMap = gson.fromJson(result, AcousticBrainzLowLevelList.class) ;


but nothing get added to the map. Unsuprisingly because data I dont' see how can i give a name since there is no consistent name at the top level.

data

Map

String

AcousticBrainzLowlevelWrapper

Map<String, AcousticBrainzLowlevelWrapper>

2 Answers
2

It seems to me that your input JSON could be parsed to produce a Java class of type Map<String,Map<Integer,AcousticBrainzLowlevelWrapper>> :

Map<String,Map<Integer,AcousticBrainzLowlevelWrapper>>

Type type = new TypeToken<Map<String,Map<Integer,AcousticBrainzLowlevelWrapper>>>().getType();
Map<String,Map<Integer,AcousticBrainzLowlevelWrapper>> result = gson.fromJson(json, type);


Type type = new TypeToken<Map<String,Map<Integer,AcousticBrainzLowlevelWrapper>>>().getType();

As I wrote it, I might as well post it:
Similar to Maurice's answer

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

import java.lang.reflect.Type;
import java.util.Map;

public class Main

private final static String jsonSingle =
" "attribute1": "value1", "attribute2": "value2" ";

private final static String jsonMultiple =
"n" +
" "96685213-a25c-4678-9a13-abd9ec81cf35": n" +
" "0": "attribute1": "value1", "attribute2": "value2" n" +
" ,n" +
" "78787888-a25c-4678-9a13-abd9ec81cf35": n" +
" "0": "attribute1": "value3", "attribute2": "value4" n" +
"";

public static void main(String args)
MyBean bean = new Gson().fromJson(jsonSingle, MyBean.class);
System.out.println(bean);

Type type = new TypeToken<Map<String, Map<String, MyBean>>>().getType();
Map<String, String> myMap = new Gson().fromJson(jsonMultiple, type);
System.out.println(myMap);




MyBean class:

class MyBean
String attribute1;
String attribute2;

public String getAttribute1()
return attribute1;


public void setAttribute1(String attribute1)
this.attribute1 = attribute1;


public String getAttribute2()
return attribute2;


public void setAttribute2(String attribute2)
this.attribute2 = attribute2;


@Override
public String toString()
return "MyBean: <attribute1: " + attribute1 + "



Outputs:

MyBean: <attribute1: value1 | attribute2: value2>


and

96685213-a25c-4678-9a13-abd9ec81cf35=0=MyBean: <attribute1: value1 , 78787888-a25c-4678-9a13-abd9ec81cf35=0=MyBean: <attribute1: value3


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