【发布时间】:2013-05-06 15:25:08
【问题描述】:
伙计们!我写了一个 Book 类,它有 Chapter 对象(一对多的关系)。它实现了方法 public List chapters(),如文档中所述。这是 Book.java
@Table(name = "Books")
public class Book extends Model implements Serializable {
private static final long serialVersionUID = 1L;
@Column(name = "Name", unique = true, onUniqueConflict = Column.ConflictAction.IGNORE)
public String name;
@Column(name = "Sort")
public int sort;
public Book() {
super();
}
public Book(String name, int sort) {
super();
this.name = name;
this.sort = sort;
}
public List<Chapter> chapters() {
return getMany(Chapter.class, "Book");
}
@Override
public String toString() {
return name;
}
}
在主要活动中,我可以成功获取章节对象。但是,我必须将 book 对象传递给另一个具有片段的活动,虽然我得到了对象的声明属性(字符串名称和 int 排序),但当我调用 chapters() 时会引发异常:
Bundle bundle = getIntent().getExtras();
Book book = (Book) bundle.getSerializable("BOOK");
// This line is executed successfully
Log.d("TAGGED", "Recovered book: " + book.name + " has " + book.sort + " as its sort");
// This is the line that throws an exception
ArrayList<Chapter> chapters = book.chapters();
抛出的异常如下:
05-06 15:21:59.701: E/AndroidRuntime(9647): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.hanovit.libraria/com.hanovit.libraria.chapter.ChapterActivity}: java.lang.NullPointerException
05-06 15:21:59.701: E/AndroidRuntime(9647): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
05-06 15:21:59.701: E/AndroidRuntime(9647): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
05-06 15:21:59.701: E/AndroidRuntime(9647): Caused by: java.lang.NullPointerException
05-06 15:21:59.701: E/AndroidRuntime(9647): at com.activeandroid.query.From.getArguments(From.java:207)
05-06 15:21:59.701: E/AndroidRuntime(9647): at com.activeandroid.query.From.execute(From.java:183)
05-06 15:21:59.701: E/AndroidRuntime(9647): at com.activeandroid.Model.getMany(Model.java:266)
任何想法有什么问题吗?谢谢!!!
【问题讨论】:
标签: android android-intent activeandroid