Can not deserialize instance of java.util.ArrayList out of START_OBJECT token

This error is usually encountered when trying to parse a JSON string that does not start with a JSON array, but rather a JSON object.

For example, if you have a JSON string like this:

{
  "name": "John",
  "age": 30,
  "city": "New York"
}

And you try to parse it using a method that expects a JSON array, such as new Gson().fromJson(jsonString, ArrayList.class), you will get the "Can not deserialize instance of java.util.ArrayList out of START_OBJECT token" error.

To fix this error, make sure that the JSON string you are trying to parse starts with a JSON array, like this:

[ { "name": "John", "age": 30, "city": "New York" }, { "name": "Jane", "age": 25, "city": "San Francisco" }]

If you are using a JSON library such as Gson, you can then parse the JSON string using the appropriate method, such as new Gson().fromJson(jsonString, ArrayList.class).