gsonpath.GsonUtil Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of gsonpath Show documentation
An annotation processor which generates Type Adapters for the Google Gson library
There is a newer version: 4.0.0
package gsonpath;

import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken;

import java.io.IOException;

/**
 * A set of Gson utilities which expose functionality to read content from a JsonReader
 * safely without throwing IOExceptions.
 */
public class GsonUtil {

    /**
     * Determines whether the next value within the reader is not null.
     *
     * @param in the json reader used to read the stream
     * @return true if a valid value exists, or false if the value is null.
     * @throws IOException see {@link JsonReader#skipValue()}
     */
    public static boolean isValidValue(JsonReader in) throws IOException {
        if (in.peek() == JsonToken.NULL) {
            in.skipValue();
            return false;
        }
        return true;
    }

    /**
     * Attempts to obtain the next string value from the reader if possible, otherwise
     * it will return null.
     *
     * @param in the json reader used to read the stream
     * @return the String value if found within the stream, otherwise null.
     * @throws IOException see {#isValidValue()} and {@link JsonReader#nextString()}
     */
    @SuppressWarnings("unused")
    public static String getStringSafely(JsonReader in) throws IOException {
        if (isValidValue(in)) {
            return in.nextString();
        }
        return null;
    }

    /**
     * Attempts to obtain the next boolean value from the reader if possible, otherwise
     * it will return null.
     *
     * @param in the json reader used to read the stream
     * @return the Boolean value if found within the stream, otherwise null.
     * @throws IOException see {#isValidValue()} and {@link JsonReader#nextBoolean()}
     */
    @SuppressWarnings("unused")
    public static Boolean getBooleanSafely(JsonReader in) throws IOException {
        if (isValidValue(in)) {
            return in.nextBoolean();
        }
        return null;
    }

    /**
     * Attempts to obtain the next integer value from the reader if possible, otherwise
     * it will return null.
     *
     * @param in the json reader used to read the stream
     * @return the Integer value if found within the stream, otherwise null.
     * @throws IOException see {#isValidValue()} and {@link JsonReader#nextInt()}
     */
    @SuppressWarnings("unused")
    public static Integer getIntegerSafely(JsonReader in) throws IOException {
        if (isValidValue(in)) {
            return in.nextInt();
        }
        return null;
    }

    /**
     * Attempts to obtain the next long value from the reader if possible, otherwise
     * it will return null.
     *
     * @param in the json reader used to read the stream
     * @return the Long value if found within the stream, otherwise null.
     * @throws IOException see {#isValidValue()} and {@link JsonReader#nextLong()}
     */
    @SuppressWarnings("unused")
    public static Long getLongSafely(JsonReader in) throws IOException {
        if (isValidValue(in)) {
            return in.nextLong();
        }
        return null;
    }

    /**
     * Attempts to obtain the next double value from the reader if possible, otherwise
     * it will return null.
     *
     * @param in the json reader used to read the stream
     * @return the Double value if found within the stream, otherwise null.
     * @throws IOException see {#isValidValue()} and {@link JsonReader#nextDouble()}
     */
    @SuppressWarnings("unused")
    public static Double getDoubleSafely(JsonReader in) throws IOException {
        if (isValidValue(in)) {
            return in.nextDouble();
        }
        return null;
    }

}