请举例说明

以下是一些Java泛型的示例：

1. 泛型类和泛型方法的定义和使用：

public class GenericClass<T> {
    private T value;

    public T getValue() {
        return value;
    }

    public void setValue(T value) {
        this.value = value;
    }

    public <E> void printArray(E[] array) {
        for (E element : array) {
            System.out.println(element);
        }
    }
}

GenericClass<String> gc = new GenericClass<>();
gc.setValue("Hello");
String value = gc.getValue(); // "Hello"

Integer[] intArray = {1, 2, 3};
gc.printArray(intArray); // 输出 1 2 3

2. 类型通配符和边界通配符的使用：

public static void printList(List<? extends Number> list) {
    for (Number n : list) {
        System.out.print(n + " ");
    }
    System.out.println();
}

List<Integer> intList = Arrays.asList(1, 2, 3);
List<Double> doubleList = Arrays.asList(1.0, 2.0, 3.0);
printList(intList); // 输出 1 2 3
printList(doubleList); // 输出 1.0 2.0 3.0

3. 泛型擦除和桥方法的理解和应用：

public class GenericClass<T> {
    public void method(T t) {
        System.out.println("Generic method");
    }
}

public class SubClass extends GenericClass<String> {
    public void method(String s) {
        System.out.println("Non-generic method");
    }
}

SubClass sc = new SubClass();
sc.method("Hello"); // 输出 Non-generic method

4. 泛型数组的创建和使用：

List<String>[] arrayOfLists = new List<String>[2]; // 编译错误
List<?>[] arrayOfLists = new List<?>[2]; // 正确的创建泛型数组的方式
arrayOfLists[0] = Arrays.asList("Hello", "World");
arrayOfLists[1] = Arrays.asList("Java", "Programming");
System.out.println(arrayOfLists[0]); // 输出 [Hello, World]

5. 泛型与继承的关系，类型参数的协变和逆变：

public class Animal {}
public class Dog extends Animal {}

public interface MyList<E> {
    void add(E e);
    E get(int index);
}

public class AnimalList implements MyList<Animal> {
    private List<Animal> list = new ArrayList<>();

    public void add(Animal animal) {
        list.add(animal);
    }

    public Animal get(int index) {
        return list.get(index);
    }
}

public class DogList implements MyList<Dog> {
    private List<Dog> list = new ArrayList<>();

    public void add(Dog dog) {
        list.add(dog);
    }

    public Dog get(int index) {
        return list.get(index);
    }
}

MyList<Animal> animalList = new AnimalList();
animalList.add(new Animal());
animalList.add(new Dog()); // 编译错误

MyList<? extends Animal> animalList = new AnimalList();
Animal animal = animalList.get(0);
Dog dog = animalList.get(1); // 编译错误

MyList<? super Dog> dogList = new AnimalList();
dogList.add(new Animal()); // 编译错误
dogList.add(new Dog());
Animal animal = dogList.get(0); // 编译错误

6. 泛型和反射的关系，泛型信息的获取和使用：

public class GenericClass<T> {
    private T value;

    public T getValue() {
        return value;
    }

    public static void main(String[] args) throws NoSuchFieldException {
        GenericClass<String> gc = new GenericClass<>();
        gc.setValue("Hello");

        Field field = GenericClass.class.getDeclaredField("value");
        Type type = field.getGenericType();
        if (type instanceof ParameterizedType) {
            ParameterizedType pType = (ParameterizedType) type;
            Type[] argTypes = pType.getActualTypeArguments();
            for (Type argType : argTypes) {
                System.out.println(argType.getTypeName()); // 输出 java.lang.String
            }
        }
    }
}

7. 泛型与异常的关系，泛型异常的捕获和处理：

public class MyException<T> extends Exception {
    private T data;

    public MyException(T data) {
        this.data = data;
    }

    public T getData() {
        return data;
    }
}

try {
    throw new MyException<String>("Error");
} catch (MyException<?> ex) {
    System.out.println(ex.getData()); // 输出 Error
}