使用泛型类型实现接口

// 定义一个泛型接口
public interface GenericInterface<T> {
    void doSomething(T t);
}

// 实现泛型接口
public class StringImplementation implements GenericInterface<String> {
    @Override
    public void doSomething(String s) {
        System.out.println("Doing something with string: " + s);
    }
}

public class IntegerImplementation implements GenericInterface<Integer> {
    @Override
    public void doSomething(Integer i) {
        System.out.println("Doing something with integer: " + i);
    }
}

// 测试类
public class Main {
    public static void main(String[] args) {
        GenericInterface<String> stringImpl = new StringImplementation();
        stringImpl.doSomething("Hello, World!");

        GenericInterface<Integer> intImpl = new IntegerImplementation();
        intImpl.doSomething(42);
    }
}

public void printList(List<?> list) {
    for (Object elem : list) {
        System.out.println(elem + " ");
    }
    System.out.println();
}

List<String> stringList = new ArrayList<>();
stringList.add("Hello");
// stringList.add(123); // 编译错误，类型不匹配