naive-json-parser

A naive parser for json string

I referred to Introducing JSON and implemented a very simple json parser.

Usage

Step 1: Build a jar file with the following command

mvn clean package

Step 2: Use this jar file to parse and pretty print json string from standard input. An example is shown below.

echo '  [   {"Message": "Hello, world", "Some special numbers": [4.2E1, 23E0,   3.14159265358979], "Today is Saturday" : true, "Needs to work": false, "Test for null": null}]' | \
  java -jar target/naive-json-parser-1.0-SNAPSHOT-jar-with-dependencies.jar

The output is like this

[
    {
        "Message": "Hello, world",
        "Some special numbers": [
            4.2E1,
            23E0,
            3.14159265358979
        ],
        "Today is Saturday": true,
        "Needs to work": false,
        "Test for null": null
    }
]

Code structure

Let's take a look at the main method in com.study.Main class

    public static void main(String[] args) throws IOException {
        try (InputStream inputStream = System.in) {
        byte[] bytes = inputStream.readAllBytes();
        String raw = new String(bytes, StandardCharsets.UTF_8);

        JsonParser jsonParser = new JsonParser();
        Json json = jsonParser.parse(new PeekingIterator<>(raw.codePoints().iterator()));

        PresenterFacade presenterFacade = new PresenterFacade();
        String result = presenterFacade.convertToString(json);
        System.out.println(result);
    }

There are 3 main steps.

1. Read from stdin
2. Parse to a Json instance
3. Present this Json instance

todo