Schwartz Transform Java 8 Version

Schwartz.java

import java.util.List;
import java.util.function.Function;
import java.util.stream.Collectors;

import org.javatuples.*;


public class Schwartz {
	public static <T> List<T> transform(List<T> list, Function<T, Integer>fn) {
		return list.stream()
			.map(x -> Pair.with(x, fn.apply(x)))
			.sorted((a, b) -> a.getValue1() - b.getValue1())
			.map(p -> p.getValue0())
			.collect(Collectors.toList());
	}
}

SchwartzTest.java

import static org.junit.Assert.*;
import static org.hamcrest.CoreMatchers.*;

import java.util.*;
import org.junit.Test;

public class SchwartzTest {

	@Test
	public void test() {
		List<String> result = Schwartz.transform(Arrays.asList("abc", "a", "cc", "abcdefg"), s -> s.length());
		assertThat(result.get(0), is("a"));
		assertThat(result.get(3), is("abcdefg"));
	}
}