Convert json string to list or map [duplicate]

问题

I get a json string in server side as follow

[     {"projectFileId":"8547",
       "projectId":"8235",
       "fileName":"1",
       "application":"Excel",
       "complexity":"NORMAL",
       "pageCount":"2",
       "targetLanguages":" ar-SA",
       "Id":"8547"
      },
      {"projectFileId":"8450",
       "projectId":"8235",
       "fileName":"Capacity Calculator.pptx",
       "application":"Powerpoint",
       "complexity":"NORMAL",
       "pageCount":"100",
       "targetLanguages":" ar-LB, ar-SA",
       "Id":"8450"
      }
]

I want to convert this string into an arraylist or map whichever possible so that I can iterate over it and get the field values.

回答1:

You can use GSON library. Simply use Gson#fromJson() method to convert JSON string into Java Object.

sample code:

BufferedReader reader = new BufferedReader(new FileReader(new File("json.txt")));
Gson gson = new Gson();
Type type = new TypeToken<ArrayList<Map<String, String>>>() {}.getType();
ArrayList<Map<String, String>> data = gson.fromJson(reader, type);

// convert back to JSON string from object
System.out.println(new GsonBuilder().setPrettyPrinting().create().toJson(data));

You can create a POJO class to convert it directly into List of POJO clas object to access it easily.

sample code:

class PojectDetail{
    private String projectFileId;
    private String projectId;
    private String fileName;
    private String application;
    private String complexity;
    private String pageCount;
    private String targetLanguages;
    private String Id;
    // getter & setter
}

Gson gson = new Gson();
Type type = new TypeToken<ArrayList<PojectDetail>>() {}.getType();
ArrayList<PojectDetail> data = gson.fromJson(reader, type);

来源：https://stackoverflow.com/questions/24939724/convert-json-string-to-list-or-map

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java

json

gson