Add Json file contents to JsonObject in Java - json

Question

I have a Json file E:\\jsondemo.json in disk. I want to create JSONObject in Java and add the contents of the json file to JSONObject. How it is possible?
JSONObject jsonObject = new JSONObject();
After creating this objec, what should i do to read the file and put values in jsonObject
Thanks.

Answer 1

You can transform a file in a String using a function proposed in this question:
private static String readFile(String path) throws IOException {
FileInputStream stream = new FileInputStream(new File(path));
try {
FileChannel fc = stream.getChannel();
MappedByteBuffer bb = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
/* Instead of using default, pass in a decoder. */
return Charset.defaultCharset().decode(bb).toString();
}
finally {
stream.close();
}
}
After getting the string, you can transform it to a JSONObject with the following code:
String json = readFile("E:\\jsondemo.json");
JSONObject jo = null;
try {
jo = new JSONObject(json);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
In the above example, I used this library, very simple to learn. You can add values to your JSON object in this way:
jo.put("one", 1);
jo.put("two", 2);
jo.put("three", 3);
You can also create JSONArray objects, and add it to your JSONObject:
JSONArray ja = new JSONArray();
ja.put("1");
ja.put("2");
ja.put("3");
jo.put("myArray", ja);