Java in-built JSON parser [closed]

Question

I've been working on a task where I need to make a request and get value of a specific key in JSON. Because of some limitations/complications, I'm suppose to use only in-built libraries of Java.

For making a request, I'm using HttpURLConnection but for parsing JSON I could not find. Could you please point me to Java in built JSON parsers.

I found similar question here but that does not have satisfactory answer and pretty old hence asking again, in case, this is available with latest versions of Java.

Answer 1

You can use built-in Nashorn engine in Java 8

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Map;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class JSONParsingTest {

    private ScriptEngine engine;

    @Before
    public void initEngine() {
        ScriptEngineManager sem = new ScriptEngineManager();
        this.engine = sem.getEngineByName("javascript");
    }

    @Test
    public void parseJson() throws IOException, ScriptException {
        String json = new String(Files.readAllBytes(/*path*/);
        String script = "Java.asJSONCompatible(" + json + ")";
        Object result = this.engine.eval(script);
        assertThat(result, instanceOf(Map.class));
        Map contents = (Map) result;
        contents.forEach((t, u) -> {
        //key-value pairs
        });
    }
}

source : Converting JSON To Map With Java 8 Without Dependencies

Disclaimer: Nashorn will be deprecated soon.

Update : Nashorn has been removed from Java 15

Answer 2

The Java API for JSON Processing provides portable APIs to parse, generate, transform, and query JSON.

Official Website Reference - https://www.oracle.com/technical-resources/articles/java/json.html