The simplest Json parser (Android)

JsonUtils.java

import android.util.JsonReader;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

import java.io.IOException;
import java.io.StringReader;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class JsonUtils {
    @Nullable
    public static Object readValue(@NonNull String json) throws IOException {
        return readValue(new JsonReader(new StringReader(json)));
    }

    @NonNull
    public static List<Object> readArray(@NonNull String json) throws IOException {
        return readArray(new JsonReader(new StringReader(json)));
    }

    @NonNull
    public static Map<String, Object> readObject(@NonNull String json) throws IOException {
        return readObject(new JsonReader(new StringReader(json)));
    }

    @Nullable
    public static Object readValue(@NonNull JsonReader reader) throws IOException {
        switch (reader.peek()) {
            case BEGIN_ARRAY:
                return readArray(reader);

            case BEGIN_OBJECT:
                return readObject(reader);

            case STRING:
                return reader.nextString();

            case NUMBER:
                return new BigDecimal(reader.nextString());

            case BOOLEAN:
                return reader.nextBoolean();

            case NULL:
                reader.nextNull();
                return null;
        }

        throw new IOException(String.valueOf(reader.peek()));
    }

    @NonNull
    public static List<Object> readArray(@NonNull JsonReader reader) throws IOException {
        reader.beginArray();

        List<Object> result = new ArrayList<>();

        while (reader.hasNext()) {
            result.add(readValue(reader));
        }

        reader.endArray();

        return result;
    }

    @NonNull
    @SuppressWarnings("ConstantConditions")
    public static Map<String, Object> readObject(@NonNull JsonReader reader) throws IOException {
        reader.beginObject();

        Map<String, Object> result = new HashMap<>();

        while (reader.hasNext()) {
            result.put(reader.nextName(), readValue(reader));
        }

        reader.endObject();

        return result;
    }
}