Filtering-Collections.java

public static <T> Collection<T> toStringFiltered(List<T> aListOfTs) {
    return Collections2.filter(aListOfTs, new Predicate<T>()
    {
        public boolean apply(T from) {
            return from.toString().isEmpty();
        }
    });
}

Google-Collections.pom.xml

<dependency>
    <groupId>com.google.collections</groupId>
    <artifactId>google-collections</artifactId>
    <version>1.0</version>
</dependency>

Transform-Collection-Google-Collections.java

public static <T> Collection<String> toString(List<T> aListOfTs) {
    return Collections2.transform(aListOfTs, new Function<T, String>()
    {
        public String apply(T from) {
            return from.toString();
        }
    });
}

Transforming-Collections-Old-School.java

public static <T> List<String> toString(List<T> aListOfTs) {
    List<String> toPrint = new ArrayList<String>();
    for (T aT : aListOfTs) {
        toPrint.add(aT.toString());
    }
    return toPrint;
}

Transforming-Collections.scala

aListOfTs.map(_.toString)