Creating a JSONObject from a File Resource

31 January 2014 - Filed under android

While writing up a unit test for a service I had written, I needed to parse out a JSON test string into a large JSON object. I found the best way to do this was to place the test data in a file located in the 'res/raw' folder (create this folder if your project does not include it already) and then read the file, and parse it as a JSON object.

private JSONObject createJSONFromFile(int fileID) {

    JSONObject result = null;

    try {
        // Read file into string builder
        InputStream inputStream = mTestContext.getResources().openRawResource(fileID);
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        StringBuilder builder = new StringBuilder();

        for (String line = null; (line = reader.readLine()) != null ; ) {
            builder.append(line).append("\n");
        }

        // Parse into JSONObject    
        String resultStr = builder.toString();
        JSONTokener tokener = new JSONTokener(resultStr);
        result = new JSONObject(tokener);
    }
    catch (Exception ex) {
        ex.printStackTrace();   
    }

    return result;
}

private void loadTestFile() {
    JSONObject test = createJSONFromFile(R.raw.testdata_valid);
    // ... do awesome stuff with test data ...
}

Note: It is good practice to place large sets of test data in resource files (and not simply hard code data strings into a test object). Since a string literal (or constant String expression) cannot be more than 65535 characters(1) you may run into problems manually building projects that contain these large strings.

References:

(1) Java class file format docs

_{by Shayla Sawchenko}

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