11. public void addStrings(List list) {
12. list.add(”foo”);
13. list.add(”bar”);
14. }
What must you change in this method to compile without warnings?
A. add this code after line 11:
list = (List<String>) list;
B. change lines 12 and 13 to:
list.add<String>(”foo”);
list.add<String>(”bar”);
C. change the method signature on line 11 to:
public void addStrings(List<? extends String> list) {
D. change the method signature on line 11 to:
public void addStrings(List<? super String> list) {
E. No changes are necessary. This method compiles without warnings.
12. list.add(”foo”);
13. list.add(”bar”);
14. }
What must you change in this method to compile without warnings?
A. add this code after line 11:
list = (List<String>) list;
B. change lines 12 and 13 to:
list.add<String>(”foo”);
list.add<String>(”bar”);
C. change the method signature on line 11 to:
public void addStrings(List<? extends String> list) {
D. change the method signature on line 11 to:
public void addStrings(List<? super String> list) {
E. No changes are necessary. This method compiles without warnings.
语法并没错误,但是跟你顶楼的问题一样,有警告啊:Multiple ers at this line
- The value of the local variable list is not used
- List is a raw type. References to generic type List<E> should be parameterized
- ArrayList is a raw type. References to generic type ArrayList<E> should be parameterized
请问一下,这句是什么意思呀?