How to convert Java object to JSON or JSON to java object in java

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 Quick Reference

toJson() – Convert Java object to JSON

Gson gson = new Gson();
<Java class> obj = new <Java class>();

// 1. Java object to JSON, and save into a file
gson.toJson(obj, new FileWriter("C:\\file.json"));

// 2. Java object to JSON, and assign to a String
String jsonInString = gson.toJson(obj);

fromJson() – Convert JSON to Java object

Gson gson = new Gson();

// 1. JSON to Java object, read it from a file.
<Java class>staff = gson.fromJson(new FileReader("D:\\file.json"), <Java class>.class);

// 2. JSON to Java object, read it from a Json String.
String jsonInString = "{'name' : 'mkyong'}";
Staff staff = gson.fromJson(jsonInString, <Java class>.class);

// JSON to JsonElement, convert to String later.
JsonElement json = gson.fromJson(new FileReader("D:\\file.json"), JsonElement.class);
    String result = gson.toJson(json);