java里null强转为某个类会报错吗?

/**
 * @author lizhibiao
 * @date 2018/11/27 17:21
 */
public class User
{
    private String userName;

    private int age;

    private int cutScore;

    public String getUserName()
    {
        return userName;
    }

    public void setUserName(String userName)
    {
        this.userName = userName;
    }

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }

    public int getCutScore() {
        return cutScore;
    }

    public void setCutScore(int cutScore) {
        this.cutScore = cutScore;
    }
}

public class Test
{
    public static void main(String[] args)
    {
        User user = (User)null;
        System.out.println(user);
    }
}

public class Test
{
    public static void main(String[] args)
    {
        User user = (User)null;
        System.out.println(user.getUserName());
    }
}