Question

I want to know how to deformat Gson arraylist of an object

I have the following class Disease

public class Disease {

    private int diseaseID;
    private String diseaseName;
    private String diseaseDescription;
    private String diseaseImageURL;
}

with setters and getters of the variables.

I have a spinner in android layout that I would like to fill with diseases names.

below is the spinner code

<Spinner
       android:id="@+id/consultation_deseases"
       android:layout_width="@dimen/bigSpinnerWidth"
       android:layout_height="@dimen/bigSpinnerHeight"
       android:prompt="@string/disease_prompt" />

now the diseases names will be sent from web service whose response will be in Gson format like this

[{"diseaseName":"Obesity","diseaseID":0},{"diseaseName":"Influenza","diseaseID":1},{"diseaseName":"Smoking","diseaseID":2},{"diseaseName":"FSD","diseaseID":3},{"diseaseName":"STI/STD","diseaseID":4}]

I tried to use the below code

Disease dis = gson.fromJson(json, Disease.class); 

but I got the following error

08-12 11:29:18.273: E/AndroidRuntime(7518): FATAL EXCEPTION: main
08-12 11:29:18.273: E/AndroidRuntime(7518): com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2
08-12 11:29:18.273: E/AndroidRuntime(7518):     at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:180)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at com.google.gson.Gson.fromJson(Gson.java:755)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at com.google.gson.Gson.fromJson(Gson.java:721)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at com.google.gson.Gson.fromJson(Gson.java:670)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at com.google.gson.Gson.fromJson(Gson.java:642)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at com.example.onlineconsultation.LoginActivity$3.onClick(LoginActivity.java:117)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at android.view.View.performClick(View.java:3558)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at android.view.View$PerformClick.run(View.java:14152)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at android.os.Handler.handleCallback(Handler.java:605)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at android.os.Handler.dispatchMessage(Handler.java:92)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at android.os.Looper.loop(Looper.java:137)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at android.app.ActivityThread.main(ActivityThread.java:4514)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at java.lang.reflect.Method.invokeNative(Native Method)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at java.lang.reflect.Method.invoke(Method.java:511)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at dalvik.system.NativeStart.main(Native Method)
08-12 11:29:18.273: E/AndroidRuntime(7518): Caused by: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2
08-12 11:29:18.273: E/AndroidRuntime(7518):     at com.google.gson.stream.JsonReader.expect(JsonReader.java:339)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at com.google.gson.stream.JsonReader.beginObject(JsonReader.java:322)
08-12 11:29:18.273: E/AndroidRuntime(7518):     at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:168)

the error is in this line

Disease dis = gson.fromJson(json, Disease.class); 

PROBLEM SOLVED : Disease[] dis = gson.fromJson(json, Disease[].class);

I was smart enough to recognize I should get the response in an array of Disease instead of Disease object =)

Answer 1

USE : Disease[] dis = gson.fromJson(json, Disease[].class);

instead of Disease dis = gson.fromJson(json, Disease.class);