Java in-built JSON parser

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.

AFAIK, Java does not provide any native library for processing JSON. — LHCHIN, Jan 20 '20 at 10:08

Smile · Answer 1 · 2021-02-25T09:40:43.800

4

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

edited Feb 25 '21 at 09:40

answered Jan 20 '20 at 09:22

Smile

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Yes; however, keep in mind that nashorn will be drop in a future release. – Maurice Perry Jan 20 '20 at 10:18
@MauricePerry Thanks for reminding. i have added this to my answer. – Smile Jan 20 '20 at 10:22
@Smile Nashorn has been removed in JDK 15 – tibetiroka Feb 25 '21 at 09:17
@tibetiroka Updated my answer to reflect that, thanks. – Smile Feb 25 '21 at 09:41

score 2 · Answer 2 · answered Jan 20 '20 at 09:20

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

answered Jan 20 '20 at 09:20

Suryakant Bharti

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OP wants to use built-in libraries. This is an API and you would need to use a 3rd implementation library. – Smile Jan 20 '20 at 10:19

score 0 · Answer 3 · answered Jan 20 '20 at 09:21

0

There is no such libraries in Java. But if you use maven, you can add GSON or JSON-lib dependencies.

answered Jan 20 '20 at 09:21

devNNP

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OP has said that he want to use only built-in libraries in Java. – LHCHIN Jan 20 '20 at 09:57

Java in-built JSON parser

3 Answers3