Java Generics 特例

class Animal {public void test(List<Integer> list) { };public void test(List<String> list) { };    // compile error}

class Animal {}class Dog extends Animal {}class Cat extends Animal {}public static void main(String[] args) {Animal a = new Animal();Dog b = new Dog();ArrayList<Animal> la = new ArrayList<Animal>();ArrayList<Dog> lb = new ArrayList<Dog>();la = lb;   //  compile errorlb = la;   //  compile error        }

refer: http://tutorials.jenkov.com/java-generics/wildcards.html