Java下面这段代码错在哪里呢？
其中Child是Parent的子类。
public static void main(String[] args) {
Child child = new Child();
List<Child> childList = new ArrayList<Child>();
childList.add(child);
testList(childList);
Map<String, Child> childMap = new HashMap<String, Child>();
testMap(childMap);
}
private static void testList(List<? extends Parent> parent) {
Child child3 = new Child();
parent.add(child3);
}
private static void testMap(Map<String, ? extends Parent> parent) {
Child child2 = new Child();
parent.put("test", child2);
}
private static void testList(List<? super Child> parent) { Child child3 = new Child(); parent.add(child3); } private static void testMap(Map<String, ? super Child> parent) { Child child2 = new Child(); parent.put("test", child2); }