import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

public class CreateUnmodifiableCollection {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Collection c = java.util.Arrays.asList("asdf", "java");
    System.out.println(unmodifiableCollection(c));
}
/**
 * @return an <b>UNMODIFIABLE</b> Collection&lt;T&gt;
 */
public static <T> Collection<T> unmodifiableCollection(
        final Collection<? extends T> c) {
    return (c == null) ? Collections.<T> emptyList() : Collections
            .unmodifiableCollection(c);
}

public static <T> List<T> asList(final Iterable<? extends T> iterable) {
    return (iterable instanceof Collection) ? new LinkedList<T>(
            (Collection<? extends T>) iterable) : new LinkedList<T>() {
        private static final long serialVersionUID = 3109256773218160485L;
        {
            if (iterable != null) {
                for (final T t : iterable) {
                    add(t);
                }
            }
        }
    };
}

public static <T> List<T> asList(final T t, final T... ts) {
    final ArrayList<T> list = new ArrayList<T>(ts.length + 1);
    list.add(t);
    Collections.addAll(list, ts);
    return list;
}

}
Console：
[asdf, java]