gson-sample.java

public class ResponseData {
    private List<Item> data;
    // Getter, Setter 省略

    static class Item {
        private Integer itemCode;
        private String itemName;
        private Integer itemPrice;
        // Getter, Setter 省略
    }
}

Gson gson = new Gson();
ResponseData res = gson.fromJson(new FileReader(“items.json”), ResponseData.class);

assertThat(res.getData().get(0).getItemCode(), is(91));