PairExtractor Type — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/json/JsonWriter.java lines 889–935

	interface PairExtractor<E> {

		/**
		 * Extract the name.
		 * @param <N> the name type
		 * @param element the source element
		 * @return the extracted name
		 */
		<N> N getName(E element);

		/**
		 * Extract the name.
		 * @param <V> the value type
		 * @param element the source element
		 * @return the extracted value
		 */
		<V> V getValue(E element);

		/**
		 * Factory method to create a {@link PairExtractor} using distinct name and value
		 * extraction functions.
		 * @param <T> the element type
		 * @param nameExtractor the name extractor
		 * @param valueExtractor the value extraction
		 * @return a new {@link PairExtractor} instance
		 */
		static <T> PairExtractor<T> of(Function<T, ?> nameExtractor, Function<T, ?> valueExtractor) {
			Assert.notNull(nameExtractor, "'nameExtractor' must not be null");
			Assert.notNull(valueExtractor, "'valueExtractor' must not be null");
			return new PairExtractor<>() {

				@Override
				@SuppressWarnings("unchecked")
				public <N> N getName(T instance) {
					return (N) nameExtractor.apply(instance);
				}

				@Override
				@SuppressWarnings("unchecked")
				public <V> V getValue(T instance) {
					return (V) valueExtractor.apply(instance);
				}

			};
		}

	}