数组列表中parcelable对象 [英] Arraylist in parcelable object

问题描述

我看过很多parcelable例子，到目前为止，但由于某种原因，我不能让它开始工作时，它变得更加复杂一点。 我有一个Movie对象，它实现Parcelable。本书对象包含一些属性，如的ArrayList。 执行ReadTypedList当运行我的应用程序导致NullPointerException异常！我真的没了主意这里

I have seen many parcelable examples so far, but for some reason I can't get it to work when it gets a bit more complex. I have a Movie object, which implements Parcelable. This book object contains some properties, such as ArrayLists. Running my app results in a NullPointerException when executing the ReadTypedList ! I'm really out of ideas here

public class Movie implements Parcelable{
   private int id;
   private List<Review> reviews
   private List<String> authors;

   public Movie () {
      reviews = new ArrayList<Review>();
      authors = new ArrayList<String>();
   }

   public Movie (Parcel in) {
      readFromParcel(in);
   }

   /* getters and setters excluded from code here */

   public void writeToParcel(Parcel dest, int flags) {

      dest.writeInt(id);
      dest.writeList(reviews);
      dest.writeStringList(authors);
   }

   public static final Parcelable.Creator<Movie> CREATOR = new Parcelable.Creator<Movie>() {

      public MoviecreateFromParcel(Parcel source) {
         return new Movie(source);
      }

      public Movie[] newArray(int size) {
         return new Movie[size];
      }

   };

   /*
    * Constructor calls read to create object
    */
   private void readFromParcel(Parcel in) {
      this.id = in.readInt();
      in.readTypedList(reviews, Review.CREATOR); /* NULLPOINTER HERE */
      in.readStringList(authors);
   }
}

述评类：

    public class Review implements Parcelable {
   private int id;
   private String content;

   public Review() {

   }

   public Review(Parcel in) {
      readFromParcel(in);
   }

   public void writeToParcel(Parcel dest, int flags) {
      dest.writeInt(id);
      dest.writeString(content);
   }

   public static final Creator<Review> CREATOR = new Creator<Review>() {

      public Review createFromParcel(Parcel source) {
         return new Review(source);
      }

      public Review[] newArray(int size) {
         return new Review[size];
      }
   };

   private void readFromParcel(Parcel in) {
      this.id = in.readInt();
      this.content = in.readString();
   }

}

我会很感激，如果有人可以只让我在正确的轨道，我已经花了相当多的时间来搜索这个！

I would be very grateful if someone could just get me on the right track, I have spend quite a bit of time searching for this one !

在adnvance感谢 韦斯利

Thanks in adnvance Wesley

推荐答案

评论和作者都是空。你应该先初始化ArrayList中。要做到这一点的方法之一是链的构造：

reviews and authors are both null. You should first initialize the ArrayList. One way to do this is chain the constructor:

public Movie (Parcel in) {
   this();
   readFromParcel(in); 
}

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