Why Does GSON Throw 'Expected BEGIN_OBJECT but was BEGIN_ARRAY' When Parsing JSON?

GSON Throwing "Expected BEGIN_OBJECT but was BEGIN_ARRAY"?

When attempting to parse a JSON string into a list of objects using GSON, you may encounter the "Expected BEGIN_OBJECT but was BEGIN_ARRAY" error. This occurs when the provided JSON data is an array, while you're expecting an object.

To resolve this issue, you should adjust your parsing code to accommodate the array structure. Here's a breakdown of the problem and the proper solution:

Problem:

The JSON data provided is an array of objects rather than a single object. Your code, however, tries to parse it as a single object, resulting in the error.

Solution:

To fix it, you need to specify that the JSON represents an array of objects. This can be done by modifying your code to parse the JSON into an array of your object class:

ChannelSearchEnum[] enums = gson.fromJson(jstring, ChannelSearchEnum[].class);

This way, GSON will correctly parse the JSON as an array of ChannelSearchEnum objects.

Alternative Solution:

For more flexibility, you can use the TypeToken class to define a parameterized type for the collection you want to parse into, as seen below:

Type collectionType = new TypeToken<Collection<ChannelSearchEnum>>() {}.getType();
Collection<ChannelSearchEnum> enums = gson.fromJson(jstring, collectionType);

This approach allows you to parse the JSON into a collection of ChannelSearchEnum objects, which can be a List, Set, or any other collection type.

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