验证扩展RealmObject的类的所有对象都是空的

Question

我的Book.class扩展了realmobject。

public class Book extends RealmObject {
    private String title;
    private String author;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }
}

如何判断这些物品是否为空，有人帮助我