T就是将类型固定
public class CollectionGenFoo<T extends Collection> {
...
}
?就是将不固定类型
public class CollectionGenFoo<? extends Collection> {
...
}
public class CollectionGenFoo<T extends Collection> {
...
}
?就是将不固定类型
public class CollectionGenFoo<? extends Collection> {
...
}