How to write to a json file which is stored in asset folder?

Question

I have a config.json file in the asset folder in my application. Now the scenario is, I will pull a JSON content from server and will update(override) the config.json file stored in asset folder. How can I achieve this? Here is sample of JSON:

{
    "id": 1,
    "name": "A green door",
    "price": 12.50,
    "tags": ["home", "green"]
}

I am able to read the file from the asset folder. But how to write in that file?:

public String loadJSONFromAsset() {
    String json = null;
    try {
        InputStream is = getActivity().getAssets().open("config.json");
        int size = is.available();
        byte[] buffer = new byte[size];
        is.read(buffer);
        is.close();
        json = new String(buffer, "UTF-8");
    } catch (IOException ex) {
        ex.printStackTrace();
        return null;
    }
    return json;
}

there is no way to modify APK content from within the same application. Therefore you **can't** write to assets file — Vladyslav Matviienko, Apr 02 '18 at 10:00
any other opinion ? How can I write to a local file ? @ישואוהבאותך — sagar suri, Apr 02 '18 at 10:00
Possible duplicate of [Save a (.txt) file to the Assets Folder in Android?](https://stackoverflow.com/questions/9781809/save-a-txt-file-to-the-assets-folder-in-android) — MuhammadAliJr, Apr 04 '18 at 20:31

ישו אוהב אותך · Accepted Answer · 2018-04-02T10:10:10.660

You can't write to asset folder. because it's a read-only folder. Instead, you need to save the file to your app folder. Whenever you want to use the config, check if the file is existed in your app folder. if it's exist, use it, if not, use the default one.

For example, when you get the config.json, save the file:

String filename = "config.json";
String fileContents = "Your config content..";
FileOutputStream outputStream;

try {
    outputStream = openFileOutput(filename, Context.MODE_PRIVATE);
    outputStream.write(fileContents.getBytes());
    outputStream.close();
} catch (Exception e) {
    e.printStackTrace();
}

Then, whenever you want to use, read it:

File file = new File(context.getFilesDir(), "config.json");

String config = "";
if(file.exists()) {
  // use the config.
} else {
  // use the config from asset.
}

Read more at Save Files on Device Storage for saving the file.

Amazing. Thanks for the help. I got it – sagar suri Apr 02 '18 at 10:32 — sagar suri, Apr 02 '18 at 10:32

score 3 · Answer 2 · answered Apr 02 '18 at 10:03

Whatever the files we keep in assets folder, it can not be modified at run time. Within an APK, files are read-only. Neither we can delete nor we can create any files within this directory.

What you can do is write your new JSON to a file (e.g., getFilesDir()) As this answers suggests

score 2 · Answer 3 · answered Apr 02 '18 at 10:01

2

You cannot write data to asset/Raw folder, since it is packed(.apk) and not expandable in size. check here

answered Apr 02 '18 at 10:01

Sabyasachi

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Any other way to achieve this ? @ss_ – sagar suri Apr 02 '18 at 10:02
You can use local storage like Internal storage,External storage,Shared preferences,Databases – Sabyasachi Apr 02 '18 at 10:03

How to write to a json file which is stored in asset folder?

3 Answers3