how to parse JSON file with GSON

Question

I have a very simple JSON with reviews for products  like        reviewerID    A2XVJBSRI3SWDI       asin    0000031887       reviewerName    abigail       helpful    0  0       unixReviewTime   1383523200      reviewText    Perfect red tutu for the price         overall   5 0      reviewTime    11 4  2013    summary    Nice tutu          reviewerID    A2G0LNLN79Q6HR       asin    0000031887       reviewerName    aj 18   Aj 18         helpful    1  1       unixReviewTime   1337990400      reviewText    This was a really cute      overall   4 0     reviewTime    05 26  2012      summary    Really Cute but rather short       I d like to read it into my Java app using GSON  I have built a class to hold results for each review   public class Review       private String reviewerID      private String asin      private String reviewerName      private ArrayList lt Integer gt  helpful      private String reviewText      private Double overall      private String summary      private Long unixReviewTime      private String reviewTime       public Review             this helpful   Lists newArrayList                 some getters and setters      To read the JSON file  my code is   Gson gson   new Gson    JsonReader reader   new JsonReader new FileReader filename    Review data   gson fromJson reader  Review class   data toScreen       prints to screen some values   With this code  I can only retrieve the first review in the JSON  so my question is  how to iterate through all the reader and get the next reviews  I don t need to store the reviews in a List  just need to access the object once  Any help more than welcome

User · Answer

just parse as an array   Review   reviews   new Gson   fromJson jsonString  Review   class     then if you need you can also create a list in this way   List lt Review gt  asList   Arrays asList reviews     P S  your json string should be look like this                    reviewerID    A2SUAM1J3GNN3B1            asin    0000013714            reviewerName    J  McDonald            helpful    2  3            reviewText    I bought this for my husband who plays the piano             overall   5 0           summary    Heavenly Highway Hymns            unixReviewTime   1252800000           reviewTime    09 13  2009                        reviewerID    A2SUAM1J3GNN3B2            asin    0000013714            reviewerName    J  McDonald            helpful    2  3            reviewText    I bought this for my husband who plays the piano             overall   5 0           summary    Heavenly Highway Hymns            unixReviewTime   1252800000           reviewTime    09 13  2009

User · Answer

You have to fetch the whole data in the list and then do the iteration as it is a file and will become inefficient otherwise   private static final Type REVIEW TYPE   new TypeToken lt List lt Review gt  gt        getType    Gson gson   new Gson    JsonReader reader   new JsonReader new FileReader filename    List lt Review gt  data   gson fromJson reader  REVIEW TYPE      contains the whole reviews list data toScreen       prints to screen some values

User · Answer

In case you need to parse it from a file  I find the best solution to use a HashMap lt String  String gt  to use it inside your java code for better manipultion    Try out this code   public HashMap lt String  String gt  myMethodName   throws FileNotFoundException       String path    absolute path to your file       BufferedReader bufferedReader   new BufferedReader new FileReader path         Gson gson   new Gson        HashMap lt String  String gt  json   gson fromJson bufferedReader  HashMap class       return json

[java] how to parse JSON file with GSON

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