Java streaming

CollectionStreamUtil.java

package com.snekse.java.utils

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

public class CollectionStreamUtil {
    public static <T, R> List<R> mapToList(Collection<T> i, Function<T, R> f) {
        return i.stream().map(f).collect(Collectors.toList());
    }
}

CollectionStreamUtilTest.java

package com.snekse.java.utils

import org.junit.Test;

import java.util.Arrays;
import java.util.List;

public class CollectionStreamUtilTest {

    @Test
    public void mapToList() {
        List<Integer> result = CollectionStreamUtil.mapToList(Arrays.asList("One", "Two", "Three", "Four"), String::length);
        int sum = result.stream().mapToInt(Integer::intValue).sum();

        assert 154 == sum;
        // assertEquals(15, sum);
    }
}