Java do not compile generics

Question

declaration:
ListUtil.java
public static <T, F extends T, E extends T> List<T> addAll(List<F> list1, List<E> list2) {
List<T> ret = new ArrayList<T>();
if (list1 != null) {
for (F f : list1) {
ret.add(f);
if (list2 != null) {
for (E e : list2) {
ret.add(e);
return ret;
usage:
List&lt;B&gt; bb = new ArrayList&lt;B&gt;();
List&lt;C&gt; cc = new ArrayList&lt;C&gt;();
List&lt;AAbstract&gt; ret = ListUtil.addAll(compounds, sensors);
error:
[javac] SensorInstanceMgmt.java:1113: <T,F,E>addAll(java.util.List<F>,java.util.List<E>) in util.ListUtil cannot be applied to (java.util.List<entity.B>,java.util.List<entity.C>)
[javac] List<AAbstract> ret = ListUtil.addAll(compounds, sensors);
It works in eclipse, but compiling by ant do not. I suspect some switch of javac - but do not know which.
Of course eclipse and ant uses same javac, it has set same java, javac.target, javac.source as well.
So why I compile with ant? I mention about ant but same situation will be with invoking javac from outside eclipse.
Edited by: 802651 on 2010-10-14 23:19
Edited by: 802651 on 2010-10-22 06:03

Answer 1

Different compilers handle generics slightly differently. Sun's compiler tends to a bit dumb when it comes to inferred types. I suggest you try the following which may help, or get a clearer error message.
List<AAbstract> ret = ListUtil.<AAbstract>addAll(compounds, sensors);
BTW: what is wrong with the List.addAll() method?
public static <T, F extends T, E extends T> List<T> addAll(List<F> list1, List<E> list2) {
    List<T> ret = new ArrayList<T>();
    if (list1 != null) ret.addAll(list1);
    if (list2 != null) ret.addAll(list2);
    return ret;
}